From cat-dist Mon Jan 4 21:58:10 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id UAA02897 for categories-list; Mon, 4 Jan 1999 20:34:38 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Date: Mon, 4 Jan 1999 21:41:14 GMT From: Paul Taylor Message-Id: <199901042141.VAA23513@ruby.dcs.qmw.ac.uk> To: categories@mta.ca Subject: categories: An Abstract Stone Duality Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: On 29 June 1997, I announced on "categories" my "Euclidean principle" f(a) & a = f(true) & a which holds for any support classifier or dominance Sigma (ie subobject classifier as in an elementary topos, but for any class of monos, eg open or RE subsets), where a:X->Sigma and f:X x Sigma -> Sigma. I gave a talk about this at the Category Theory meeting in Vancouver that year. At the Category Theory meeting in Tours in 1994 I talked about taking Par\'e's theorem (that the contravariant powerset functor in a topos, which is self-adjoint, is monadic) as an axiom. Another category with this property is the category of locally compact locales, where Sigma is the Sierpinski space and "powerset" means "lattice of open sets", equipped with the Scott topology. This is a way of re-axiomatising general topology without the arbitrary unions in the traditional definition and in locale theory: the category of "frames" is to be both dual to the category of "spaces" and algebraic over it. I have now written up these ideas as a draft paper entitled "An Abstract Stone Duality, I: Geometric and Higher Order Logic" that you can get via my page in the Hypatia Electronic Library, which is http://hypatia.dcs.qmw.ac.uk/author/TaylorP (I sent copies of an earlier draft to a number of people in November 1998, but otherwise this is new text: it is not the same as any "notes on SDT" that you may have got from me over the web in the past.) After some discussion relating the monadic property to sobriety of spaces and spatiality of locales, I prove the converse of the basic observation about the Euclidean principle: if Sigma satisfies it and the adjunction is monadic then Sigma is the classifier for some class of monos. It is neither an axiom nor a theorem that the category has all finite limits. Indeed, the point is that equalisers etc depend on a notion of equality, which, from a computational point of view, is not as straightforward as pure mathematicians have traditionally considered it to be. Some spaces (datatypes) admit equality in a "positive" way: for example in a group given by generators and relations, or in a lambda calculus with reduction rules, we may hope to prove equality of two terms, but not inequality. On the other hand, we may hope to prove inequality of real numbers but not equality. These ideas are formalised by notions of "discrete" and "Hausdorff" spaces respectively, along with definitions of "open" and "compact". We show that the full subcategory of open discrete spaces is a pretopos, the same being true of the compact Hausdorff spaces, by showing that the coequaliser is Sigma-split. The point of Sigma-split co/equalisers is that, being equationally defined, we might hope to be able to compute with them, possibly using something like the "continuation-passing style" used in some compilers. The Euclidean principle and monadicity property are related, respectively, to the Phoa principle and repleteness in sythetic domain theory. In that subject we also need an infinitary axiom that makes all functions Scott continuous and provides fixed points; this axiom is *not* discussed in the present paper, largely because this seemed an appropriate criterion to use to divide up a rambling collection of notes into papers. The infinitary axiom and the construction of the "lift" will be considered in Part II. Under the infinitary axiom, open discrete spaces form an arithmetic universe, ie they admit N-indexed colimits and free algebras, whilst compact Hausdorff space admit limits and cofree coalgebras. You might like to consider this paper alongside the recent work of Alex Simpson and Jaap van Oosten on Synthetic Domain Theory, http://www.math.uu.nl/publications/preprints/1080.ps.gz which is very much concerned with the infinitary axiom. In particular Alex is keen to emphasise the additional completeness of the ambient category that is needed to construct infinitary co/limits and solutions of domain equations, by comparison with directed joins and fixed points of functions. He considers that some attention to the axiom of replacement is needed here, and I agree with him, though our treatments are different. My paper is written for a general mathematical audience, and argues its point of view from a position of extreme Cartesisn doubt. I feel that Alex and Jaap's work is very arcane by comparison, as it depends heavily on Hyland's effective topos. For my own views on replacement, see the final section of my book, Practical Foundations of Mathematics. I hope to be able to make an announcement about the availability of this very soon. From cat-dist Wed Jan 6 10:31:35 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id JAA21096 for categories-list; Wed, 6 Jan 1999 09:02:07 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Date: Wed, 6 Jan 1999 06:28:46 -0500 (EST) From: James Stasheff To: categories@mta.ca Subject: strictification Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: cat-dist@mta.ca Precedence: bulk Status: RO X-Status: Is there a strictification result for A_infty-cats? If so, under what hypotheses? and by whome? where? .oooO Jim Stasheff jds@math.unc.edu (UNC) Math-UNC (919)-962-9607 \ ( Chapel Hill NC FAX:(919)-962-2568 \*) 27599-3250 http://www.math.unc.edu/Faculty/jds From cat-dist Wed Jan 6 10:43:03 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id JAA08488 for categories-list; Wed, 6 Jan 1999 09:03:12 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Date: Wed, 6 Jan 1999 12:35:26 +0100 (MET) From: Jaap van Oosten Message-ID: <199901061135.MAA12430@kodder.math.uu.nl> To: categories@mta.ca Subject: categories: re: An Abstract Stone Duality Cc: jvoosten@math.uu.nl X-Sun-Charset: US-ASCII Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: This is a reaction to Paul Taylor's advertisement for his paper on Abstract Stone Duality. Paul has considered appropriate to mention the paper "Axioms and (Counter)examples in Synthetic Domain Theory" by Alex Simpson and myself, and to polemicize against it in the following way: > You might like to consider this paper alongside the recent work of Alex > Simpson and Jaap van Oosten on Synthetic Domain Theory, > http://www.math.uu.nl/publications/preprints/1080.ps.gz > which is very much concerned with the infinitary axiom. In particular > Alex is keen to emphasise the additional completeness of the ambient > category that is needed to construct infinitary co/limits and solutions > of domain equations, by comparison with directed joins and fixed points > of functions. He considers that some attention to the axiom of replacement > is needed here, and I agree with him, though our treatments are different. > > My paper is written for a general mathematical audience, and argues its > point of view from a position of extreme Cartesisn doubt. I feel that > Alex and Jaap's work is very arcane by comparison, as it depends heavily > on Hyland's effective topos. Thanks, Paul, for mentioning our paper, but since the above text is a blatant misrepresentation of its content, a correction is in order. Our paper develops the theory on the basis of 4 axioms, of which one (the \neg\neg-separatedness of \Sigma) is rather special, as we explicitly acknowledge. Otherwise the treatment is completely general, and "completeness of the ambient category" nowhere enters the picture (we do have, however, some treatment of whether the lift functor preserves internal colimits of chains). The remark about Replacement refers to other work by Alex. The axiomatic treatment raises independence questions, some of which we solve by considering models. One of these models is the effective topos. Nowhere do we hint that the effective topos should have a privileged place among models. Anyway, it is funny that our work, which builds on the tradition of turning SDT into an axiomatic theory (a process which I think is still unfinished), tradition which was started by Pino Rosolini, Wesley Phoa, Martin Hyland and Paul himself, is now found to be "arcane" (mind you, the whole subject is less than twenty years old) by Paul. Jaap van Oosten From cat-dist Wed Jan 6 16:14:06 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id PAA09245 for categories-list; Wed, 6 Jan 1999 15:12:14 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Message-Id: <6486.199901061804@papa.dcs.ed.ac.uk> X-Mailer: exmh version 2.0.2 2/24/98 To: categories@mta.ca cc: marcelo@cogs.susx.ac.uk, als@dcs.ed.ac.uk Subject: categories: Paper Announcement Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Wed, 06 Jan 1999 18:04:29 +0000 From: Alex Simpson Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: The following paper is available by anonymous FTP or over the Web Lambda Definability with Sums via Grothendieck Logical Relations by Marcelo Fiore and Alex Simpson We introduce a notion of *Grothendieck logical relation* and use it to characterise the definability of morphisms in *stable* bicartesian closed categories by terms of the simply-typed lambda calculus with finite products and finite sums. Our techniques are based on concepts from topos theory, however our exposition is elementary. The paper is written in a style appropriate for the conference Typed Lambda-Calculi and Applications where it is to be presented in April. However, we briefly discuss the true categorical content of the paper, which will be further expanded upon in a full version of the paper (forthcoming). The paper is available over the Web: http://www.dcs.ed.ac.uk/~mf/TYPES/glr.{dvi,ps} http://www.dcs.ed.ac.uk/~als/Research/glr.ps.gz or by anonymous FTP: ftp://ftp.dcs.ed.ac.uk/pub/mf/TYPES/glr.{dvi,ps} ftp://ftp.dcs.ed.ac.uk/pub/als/Research/glr.ps.gz Best wishes for a happy New Year, Alex Simpson -- Alex Simpson, LFCS, Division of Informatics, University of Edinburgh Email: Alex.Simpson@dcs.ed.ac.uk Tel: +44 (0)131 650 5113 FTP: ftp.dcs.ed.ac.uk/pub/als Fax: +44 (0)131 667 7209 URL: http://www.dcs.ed.ac.uk/home/als From cat-dist Wed Jan 6 16:14:28 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id PAA02715 for categories-list; Wed, 6 Jan 1999 15:11:24 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Date: Wed, 6 Jan 1999 17:52:25 GMT From: Paul Taylor Message-Id: <199901061752.RAA23320@ruby.dcs.qmw.ac.uk> To: categories@mta.ca Subject: categories: Synthetic Domain Theory Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: As Jaap van Oosten says, I considered appropriate to mention the paper "Axioms and (Counter)examples in Synthetic Domain Theory" by Alex Simpson and himself when I announced my own draft paper "An Absract Stone Duality". There are two reasons why I did consider this appropriate: (1) they and I both use the heading "synthetic domain theory" for our work, and I feel that their work is important and should be considered alongside mine; (2) people outside a particular discipline tend to go by the labels - "guilt by association" - so I was keen that those who had already looked at Jaap & Alex's paper (after they advertised it on "categories" before the holiday) should not assume that mine would be of the same kind. I did not "polemicize" against it. I said that I felt it was "arcane", but wanted to say something positive about it first. Unfortunately, as Alex has pointed out to me, I got the paper confused with our discussions when I visited Edinburgh shortly before Jaap's announcement. Jaap says that > it is funny that our work, which builds on the tradition of turning > SDT into an axiomatic theory (a process which I think is still unfinished), > tradition which was started by Pino Rosolini, Wesley Phoa, Martin Hyland and > Paul himself, is now found to be "arcane" (mind you, the whole subject is > less than twenty years old) by Paul. As a generality, and without wishing to take this argument any further, surely a *founder* of a theory is qualified to describe a subsequent development of it as "arcane", ie accessible only to particular specialists, and not what that founder had in mind? SDT is a minority research topic, still the plaything of a group of friends - that's what I like about it. It's not Tony Blair's New Labour Party - we *are* allowed to disagree! Anyway, since this particular beast has now been awoken from its slumbers, I want to try to explain the mathematical content of this disagreement briefly for a general audience. Probably most "categories" readers have now heard the slogan, "Domains are sets - all functions are computable" cf "Manifolds are sets - all functions are smooth". Synthetic domain theory and synthetic differential geometry are then about (1) postulating conditions on the ambient topos (category of "sets") (2) selecting from those "sets" those that are to be called "domains" or "manifolds" and (3) using these ideas to prove interesting theorems or compute programs. Much of the progress and disagreement in SDT has been about part (2). Wesley Phoa, in his 1990 Cambridge thesis under Martin Hyland's supervision, was the first to describe objects in a certain topos that looked like the "domains" in theoretical computer science, rather than like lattices in pure mathematics. (I *don't* mean to polemicize against Pino Rosolini there.) Wes defined a certain preorder on each object of the topos, and restricted to those objects for which this is a poset (antisymmetric), and further to those for which it has directed joins, a least element and therefore fixed points. In particular, Wes selected his domains by testing each one for the relevant infinitary condition. My idea, in my 1991 LiCS paper, was that the infinitary condition could be imposed on a *single* object, and the domains selected be means of a more finitary categorical notion called "repleteness" that Martin Hyland had introduced in his paper in the 1990 Como Category Theory proceedings. Alex Simpson, John Longley and Jaap van Oosten later came up with another infinitary condition, "well-completeness", and they, like Wes, select their domains by testing this for each domain. Under suitable conditions, this gives a larger full subcategory than mine. I do not dare even to give you the definition of well-completeness, let alone attempt to defend or attack it. You should read Alex and Jaap's paper for that. One of the objections to repleteness is that it is very difficult to characterise in familiar models. Pino Rosolini has (with others) investigated this, and you can find some of his results in the papers listed on his Hypatia page, http://hypatia.dcs.qmw.ac.uk/author/RosoliniG (By the way, Hypatia now has a new server and some new code. The machine on which it was living from May to December 1998 was forever crashing, partly because the mirrored papers were stored on a large collection of very old disks with a SCSI chain that made visitors to our machine room gasp in horror.) My paper is, in this context, a defence of the notion of repleteness. Since "attack is the best form of defence" it does this by replacing it with a stronger notion, namely that a certain adjunction be monadic. This has the effect of replacing the "domains" defined by ordered structures that have been in use in theoretical computer science since the early 1970s by locally compact locales. Paul From cat-dist Wed Jan 6 20:26:57 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id TAA10368 for categories-list; Wed, 6 Jan 1999 19:23:15 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Message-ID: <3693EA39.139F@mpce.mq.edu.au> Date: Thu, 07 Jan 1999 09:56:57 +1100 From: Michael Batanin Reply-To: mbatanin@mpce.mq.edu.au Organization: Maquarie University, Sydney X-Mailer: Mozilla 3.01Gold (Win95; I) MIME-Version: 1.0 To: categories@mta.ca Subject: categories: Re: strictification References: Content-Type: text/plain; charset=koi8-r Content-Transfer-Encoding: 7bit Sender: cat-dist@mta.ca Precedence: bulk Status: RO X-Status: James Stasheff wrote: > > Is there a strictification result for A_infty-cats? > If so, under what hypotheses? and by whome? where? > > .oooO Jim Stasheff jds@math.unc.edu > (UNC) Math-UNC (919)-962-9607 > \ ( Chapel Hill NC FAX:(919)-962-2568 > \*) 27599-3250 > > http://www.math.unc.edu/Faculty/jds Yes. Im my paper "Homotopy coherent category theory and A_{\infty}-structures in monoidal categories" JPAA, 123 (1988), 67-103, theorems 2.3, 2.4 and corollary 2.3.1.. In this paper I define A_{\infty}-categories as algebras in the category of K-graphs over A_{\infty}-K-operads, where K is a simplicial monoidal category with Quillen model structure such that tensor commutes with simplicial realization functor. I show that every locally fibrant A_{\infty}-category (i.e. Hom(a,b) is fibrant object in K for every a and b) is equivalent in some homotopy coherent sense to a honest K-category. Michael Batanin. From cat-dist Thu Jan 7 12:06:37 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id JAA02848 for categories-list; Thu, 7 Jan 1999 09:48:33 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Date: Thu, 7 Jan 1999 07:49:14 GMT Message-Id: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-Mailer: Eudora F1.5.4 To: categories@mta.ca From: carlos@picard.ups-tlse.fr (Carlos Simpson) Subject: categories: re: strictification Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: > > Is there a strictification result for A_infty-cats? > If so, under what hypotheses? and by whome? where? > > .oooO Jim Stasheff jds@math.unc.edu It seems that a reference for this result is a paper of Dwyer-Kan-Smith: W. Dwyer, D. Kan, J. Smith. Homotopy commutative diagrams and their realizations. JPAA 57 (1989), 5-24. This is prior to Batanin's paper (NB there is a typographical error in Batanin's message---the year of his paper is 1998 not 1988!). I found D-K-S in my bibliographic wanderings this fall. In the last section of their paper, they define the notion of ``Segal category'' and at the same time prove that any Segal category is equivalent to a strict simplicial category. The terminology ``Segal category'' is my own (D-K-S don't give this notion a name). The notion of ``Segal category'' is the Segal-delooping-machine equivalent of the notion of A_{\infty}-category. In our preprint of this summer (math.AG/9807049), A. Hirschowitz and I give a sketch of proof of the strictification result of D-K-S. We were not aware at the time of D-K-S, nor of Batanin's paper which also gives a proof and which treats a more general situation too. (I found out about Batanin's paper this fall thanks to the previous flurry of messages on ``categories'' occasionned by a question from Jim!) I don't claim to have actually understood DKS's proof because it is very short and in very abstract language; however, given that (1) all proofs of this type of strictification result are basically the same; and (2) D-K-S have a good track record; there doesn't seem to be any doubt that the proof is indeed contained in their paper. The definition of ``Segal category'' in D-K-S is of course much prior to any of my own versions of this definition. It also seems to be (as far as I know) the first occurrence of the notion of A_{\infty}-category. In this context one should point out that Jim's original notion plus all of the subsequent delooping-machine variants, are just A_{\infty}-categories with one object; and going to the case of several objects is a rather obvious embellishment, so discussing ``priority'' for this notion would seem to be arcane indeed! ---Carlos Simpson From cat-dist Fri Jan 8 13:24:33 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id LAA09218 for categories-list; Fri, 8 Jan 1999 11:54:39 -0400 (AST) X-Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id JAA07551 for categories-list; Fri, 11 Dec 1998 09:22:44 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Message-Id: To: categories@mta.ca Subject: categories: PhD position available Mime-Version: 1.0 (generated by tm-edit 7.108) Content-Type: text/plain; charset=US-ASCII Date: Fri, 11 Dec 1998 08:49:44 +0100 From: N Ghani Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: [ Note from moderator: this is a repost by request of the original sender - December Net outages may have prevented it reaching some intended recipients. Happy New Year to all, Bob ] I am currently looking for someone who wants to do a PhD on categorical models of rewriting. If you are interested, or know someone who may be, then please get in touch. You can find bits and bobs about what I have in mind from my homepage http://www.mcs.le.ac.uk/~ng13/home.html Neil Ghani From cat-dist Fri Jan 8 13:24:33 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id LAA30674 for categories-list; Fri, 8 Jan 1999 11:43:55 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Date: Fri, 8 Jan 1999 10:01:22 -0800 From: Eva SCHLAEPFER To: categories@mta.ca Subject: categories: References Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: Hello, can someone give me references for the following two constructions? - in a closed monoidal category, the multiplication on the inner hom is normally defined as the transpose of B tens (B -o B) tens (B -o B) ---> B tens (B -o B) ---> B where tens is the tensor product, -o the inner hom, the first map ev tens (B-o B) and the second ev. - A,B,C objects in a monoidal category and A is a monoid. If B is an A-right-module in the sense that there is a morphism f: B tens A ---> B which satisfies certain axioms and C is a A-left-module g:A tens C ---> C, then the quotient B tens_A C can be defined as the coequalizer of the two maps B tens g: B tens A tens C ---> B tens C and f tens C: B tens A tens C ---> B tens C Thanks, Eva Schlaepfer From cat-dist Mon Jan 11 13:20:42 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id KAA02382 for categories-list; Mon, 11 Jan 1999 10:40:49 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Date: Mon, 11 Jan 1999 08:01:08 -0500 (EST) From: Peter Freyd Message-Id: <199901111301.IAA06980@saul.cis.upenn.edu> To: categories@mta.ca Subject: categories: Terrible news -- young Myles Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: ''The death of Myles Tierney has robbed international television of one of its brightest young stars. He was a consummate professional, highly talented and highly resourceful.'' ''On top of his professional skills he was renowned among colleagues and competitors for his great good humor and generosity of spirit'' Copyright 1999 Associated Press AP Online January 11, 1999; Monday 06:23 Eastern Time SECTION: International news LENGTH: 593 words HEADLINE: AP Journalists Shot in Sierra Leone DATELINE: FREETOWN, Sierra Leone BODY: A television producer for The Associated Press was killed and an AP bureau chief was seriously wounded when their car was hit by gunfire while covering the civil war in Sierra Leone. Myles Tierney, a Kenya-based producer for Associated Press Television News, and Ian Stewart, based in Ivory Coast, were among journalists and government Information Ministry officials who were traveling Sunday in four cars through embattled downtown Freetown. They were being escorted by troops of a West African coalition force, known as ECOMOG, which is protecting the elected government. According to other journalists in the group, the AP journalists were in a station wagon that was approached by an armed man on the street in downtown Freetown. The man opened fire on the car with a semiautomatic rifle after an exchange of words with an ECOMOG soldier also riding in the car. Tierney, 34, of New York City, was shot and died instantly. Stewart, 32, suffered a head wound. AP photographer David Guttenfelder of Waukee, Iowa, was also in the car and suffered cuts from broken window glass. The journalists were rushed to a nearby ECOMOG base, and then flown to Conakry, Guinea. Stewart and Guttenfelder were transported from there to Abidjan, Ivory Coast. ''We are devastated by the news of Myles' death and Ian's serious injuries,'' said Thomas Kent, international editor of The Associated Press. ''It is another bitter example of the sacrifices made by correspondents who go in harm's way to cover the news.'' Nigel Baker, head of news at Associated Press Television News, said: ''The death of Myles Tierney has robbed international television of one of its brightest young stars. He was a consummate professional, highly talented and highly resourceful.'' Freetown has been carved into neighborhoods of rebel and loyalist control. The rebel Revolutionary United Front controls most of eastern Freetown and parts of the downtown, and has rejected calls for a cease-fire. Sporadic shelling had been heard overnight, but street-to-street fighting had tapered off Sunday morning. State-controlled radio warned all civilians to stay indoors, saying loyalist troops were patrolling the streets in search of rebel fighters who have been using residents as human shields. Tierney joined AP as a freelance producer for the agency's TV division in Africa during 1996, organizing coverage of a military coup in Burundi. Later that year he joined the staff and set up the agency's first TV bureau in New York. In January 1997, he shifted to Africa, based in Nairobi. For the next two years he chronicled the turmoil across east and west Africa. He was part of an AP team that for three months reported exclusively on the advance of then rebel leader Laurent Kabila in eastern Zaire, now Congo. During the assignment, he pioneered use of new technology which allowed video to be dispatched over a conventional satellite telephone. It meant the TV coverage was ahead of all opposition. He also had covered conflicts in Rwanda, Guinea-Bissau, Eritrea and Somalia. ''On top of his professional skills he was renowned among colleagues and competitors for his great good humor and generosity of spirit,'' Baker said. Stewart is AP's West Africa bureau chief, based in Abidjan. He began working for AP in Pakistan, moved on to Hanoi in 1996 and began his present assignment last year. A Toronto native, he graduated from Queen's University in Kingston, Ontario, and has a master's degree from Columbia University's Graduate School of Journalism. From cat-dist Tue Jan 12 13:28:05 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id KAA28546 for categories-list; Tue, 12 Jan 1999 10:15:36 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Date: Tue, 12 Jan 1999 07:05:10 -0500 (EST) From: Peter Freyd Message-Id: <199901121205.HAA13201@saul.cis.upenn.edu> To: categories@mta.ca Subject: categories: AP on young Myles Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: Slain, Wounded Journalists Praised By TED ANTHONY AP National Writer 902 Words 5682 Characters 01/12/99 AP Online International Copyright 1999 The Associated Press. All Rights Reserved. They came from all over one continent - from New York City, from Ontario, from Iowa - to cover a war in the corner of another, to tell the world about a place that few had heard of and even fewer had ever considered visiting. Myles Tierney, Ian Stewart and David Guttenfelder, journalists for The Associated Press in Africa, brought a long list of reporting credits - and risks - to their assignment in the chaotic West African nation of Sierra Leone. But on a hot, sunny Sunday, the dizzying unpredictability so familiar to those who have covered Africa caught up with them for several seconds. Tierney, 34, from New York City, a Kenya-based producer for Associated Press Television News who one colleague said "lived his life like it was the 100-yard dash," was killed instantly when a rebel soldier peppered the AP vehicle with gunfire. Stewart, 32, from Toronto, known for chasing one story and coming back with many more, was seriously wounded in the head. Guttenfelder, 29, of Waukee, Iowa, one of the AP's most intrepid photographers, was cut by flying glass and was the only one of the three who escaped serious injury. "They just wanted to kill someone. Maybe we were the closest to them," Guttenfelder said Monday from his home base, the AP's West Africa bureau in Abidjan, Ivory Coast. Stewart, the West Africa chief of bureau, was airlifted Monday to London, where he was to undergo surgery for a bullet in the brain. He was in stable condition Monday night. AP President Louis D. Boccardi praised Tierney as "a brave and adventurous man" and mourned the attack. "We are in awe of the sacrifices they and others make so we can carry out our mission," Boccardi said Monday. "Africa was the opportunity in his life to realize himself," said Tierney's mother, Hanne. "And he did. This was where all of his talents really came to the fore." Guttenfelder recounted a surreal day that began at a hotel outside downtown Freetown, the unstable capital, with the AP journalists and their colleagues from other organizations trying to obtain firsthand information about the situation in the city. They'd tried to move around Saturday but couldn't because of the warfare on the streets. Sunday seemed less tense, Guttenfelder said. On the street they came upon Julius Spencer, Sierra Leone's minister of communications, who offered to escort them into town. With him were soldiers from ECOMOG, the West African regional peacekeeping force. "He said ... it was a matter of mopping up," Guttenfelder said. "He wanted to show us - and us to show the world - that they were very much in control." The journalists were skeptical, but they saw subtle signs of improvement: troops moving freely, gasoline stations reopening. As they neared downtown, and part of the convoy headed down to take a look at the city's center, shots reverberated in the distance. Down a hill they went, past the soccer stadium, past hulks of blown-up cars, past fallen traffic lights, past shuttered buildings, past corpses set upon by vultures. Then, around a corner, they encountered five armed men in American- style jeans and flipflops. One, Guttenfelder remembered, "was wearing a black bowler hat - like in `A Clockwork Orange."' No one was sure: Were they rebels or looters? "They looked kind of charged up, maybe drugged up. They were smiling, kind of laughing, acting like everything was cool," Guttenfelder said. "I felt immediately they were different. ... (But) it seemed impossible that a rebel would get that close." Then, in seconds: An ECOMOG soldier spoke to the men in a Nigerian tongue; one responded in another dialect. And things fell apart. One armed man fired a burst of shots into the AP car - a brazen act, given the ECOMOG firepower surrounding him.. "I get the feeling that he knew they were going to be killed, and they didn't care," Guttenfelder said. Tierney died instantly. Stewart went down moaning. "I just felt this blast of heat and glass," Guttenfelder said. "I immediately put my head down and I heard shooting for a couple of seconds. ... Myles was obviously dead. ... I grabbed Ian and drug him down into the car, then got out of the car into the street. ECOMOG soldiers fired back, killing the shooter and another rebel. The driver took off with Stewart and Tierney to the ECOMOG staging area in western Freetown. Guttenfelder was left behind. He shot a few pictures, then hurried to the base to help arrange an airlift for Stewart and for Tierney's body. Though he was a cameraman, Tierney's byline appeared on a range of stories from Africa. He joined AP's TV arm in 1996, organizing coverage of a military coup in Burundi. He set up the agency's first TV bureau in New York before returning to Africa in 1997. Tierney is survived by his mother and a sister, Loren, both of New York City. The family planned a private funeral; the AP was arranging a memorial service. The AP has withdrawn all foreign journalists from Sierra Leone for now. Tierney is the 24th AP journalist to die in the line of duty in the organization's 150-year history. On Monday, at AP headquarters in New York City, his picture was posted in memoriam. In it, he appears dressed for action. Atop his head is an AP hat. And he is smiling. From cat-dist Wed Jan 13 16:41:33 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id OAA29246 for categories-list; Wed, 13 Jan 1999 14:37:14 -0400 (AST) X-Authentication-Warning: caruaru.di.ufpe.br: ruy owned process doing -bs Date: Mon, 11 Jan 1999 17:18:25 -0300 (EST) From: Ruy de Queiroz X-Sender: ruy@caruaru To: categories@mta.ca Subject: categories: 6th WoLLIC'99 - 3rd Call Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: Call for Contributions 6th Workshop on Logic, Language, Information and Computation (WoLLIC'99) May 25-28, 1999 ! TUTORIALS >> (Tutorial Day: May 25th) << TUTORIALS ! Itatiaia National Park (Rio de Janeiro), Brazil The "6th Workshop on Logic, Language, Information and Computation" (WoLLIC'99), the sixth version of a series of workshops which started in 1994 with the aim of fostering interdisciplinary research in pure and applied logic, will be held in Itatiaia (Rio de Janeiro), Brazil, from May 25th to 28th 1999, in conjunction with the "XII Encontro Brasileiro de Logica" (EBL'99). Contributions are invited in the form of short papers (10 A4 10pt pages) in all areas related to logic, language, information and computation, including: pure logical systems, proof theory, model theory, algebraic logic, type theory, category theory, constructive mathematics, lambda and combinatorial calculi, program logic and program semantics, logics and models of concurrency, logic and complexity theory, nonclassical logics, nonmonotonic logic, logic and language, discourse representation, logic and artificial intelligence, automated deduction, foundations of logic programming, logic and computation, and logic engineering. The 6th WoLLIC'99 has the scientific sponsorship of the Association for Symbolic Logic (ASL), the Interest Group in Pure and Applied Logics (IGPL), the European Association for Logic, Language and Information (FoLLI), the Sociedade Brasileira de Computacao (SBC), and the Sociedade Brasileira de Logica (SBL). There will be a number of guest speakers, including: Samson Abramsky (Edinburgh Univ, Scotland) John Baldwin (Univ Illinois at Chicago, USA) Craig Boutilier (Univ British Columbia, Canada) Daniel Leivant (Indiana Univ, USA) Francisco Miraglia (Univ Sao Paulo, Brazil) Alan Woods (Univ Western Australia, Australia) Submission: Papers (sent preferably in postscript format by e-mail to wollic@di.ufpe.br, or in 5(five) copies to postal address) must be RECEIVED by MARCH 8th, 1999 by the Co-Chair of the Organising Committee. Papers must be ANONYMOUS (a separate identification page must be included), written in English and give enough detail to allow the programme committee to assess the merits of the work. Papers should start with a brief statement of the issues, a summary of the main results, and a statement of their significance and relevance to the workshop. References and comparisons with related work is also expected. Technical development directed to the specialist should follow. Results must be unpublished and not submitted for publication elsewhere, including the proceedings of other symposia or workshops. One author of each accepted paper will be expected to attend the conference in order to present it. Authors will be notified of acceptance by APRIL 9th, 1999, and final versions will have be delivered (in LaTeX format) by APRIL 23RD, 1999. The abstracts of the papers will be published in a "Conference Report" section of the Logic Journal of the IGPL (ISSN 1367-0751) (Oxford Univ Press) as part of the meeting report. Papers presented at the meeting will be invited for submission (in full version) to the Logic Journal of the IGPL (http://www.oup.co.uk/igpl/). Important Dates: Submission: March 8th, 1999 Notification of acceptance/rejection: April 9th, 1999 Delivery of final (in LaTeX): April 23rd, 1999 Programme Committee: Gianluigi Bellin (Univ Verona, IT) Walter Carnielli (Univ Campinas, BR) Abbas Edalat (Imperial College, UK) Rob van Glabbeek (Stanford Univ, US) Jeroen Groenendijk (Amsterdam Univ, NL) Roman Kossak (City Univ New York, US) Daniel Lehmann (Hebrew Univ Jerusalem, IL) Dusko Pavlovic (Kestrel Institute, US) Moshe Vardi (Rice Univ, US) Organising Committee: M. Benevides (COPPE/UFRJ), W. Carnielli (UNICAMP), M. Finger (USP), E. Hermann Haeusler (PUC-Rio), A. T. C. Martins (UFC), A. G. de Oliveira (UFPE/UFBA), L. C. Pereira (PUC-Rio), R. de Queiroz (UFPE) For further information, contact the Co-Chairs of the Organising Committee: Ruy de Queiroz, Departamento de Informatica, Univ. Federal de Pernambuco, CP 7851, 50732-970 Recife, PE, Brazil. E-mail: ruy@di.ufpe.br, tel.: (+55 81) 271-8430, fax: (+55 81) 271-8438. Walter Carnielli, Centro de Logica, Epistemologia e Historia da Ciencia, Univ. Estadual de Campinas, CP 6133, 13081-970 Campinas, SP, Brazil. E-mail: carniell@cle.unicamp.br, tel./fax: (+55 19) 289-3269. Web page: http://www.di.ufpe.br/~wollic/wollic99/ From cat-dist Wed Jan 13 16:41:40 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id OAA18594 for categories-list; Wed, 13 Jan 1999 14:38:20 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Message-ID: <369B8724.4B7A69D8@iswest.com> Date: Tue, 12 Jan 1999 12:32:25 -0500 From: Zhaohua Luo X-Mailer: Mozilla 4.5 [en] (Win98; U) X-Accept-Language: en MIME-Version: 1.0 To: categories@mta.ca Subject: categories: categorical geometry Content-Type: multipart/alternative; boundary="------------FF260AA9AFA537FC9D7A1021" Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: --------------FF260AA9AFA537FC9D7A1021 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit In a recent paper (TAC, Vol 4, 208-248) On Generic Separable Objects, by Robbie Gates, the author mentioned a well known "boolean algebraic structure of the summands of an object in an extensive category". This reminded me a paper I posted to my homepage last year (8/30/98, see the abstract below), in which the same boolean structure was reconstructed (at that time this was not "well known" to me), and was applied to define the Pierce topology for any extensive category, extending some results of Diers. The paper Pierce Topologies of Extensive Categories is available at Categorical Geometry Homepage at the following new (permanent, hopefully) address http://www.geometry.net (or http://www.azd.com) (The new service is a little bit slow, but offers more functions than the old one, so please be patient.) Best wishes, Zhaohua Luo ----------------------------------------------------------------------------------------- Pierce Topologies of Extensive Categories by Zhaohua Luo Abstraction An extensive category is a category with finite stable disjoint sums. In this note we show that each extensive category carries a natural subcanonical coherent Grothendieck topology defined by injections of sums. This Grothendieck topology is induced by a strict metric topology, which is a functor to the category of Stone spaces. We call this metric topology the Pierce topology of the category, as it generalizes the classical Pierce spectrums of commutative rings. Recall that the Pierce spectrum of a commutative ring R is the spectrum of the Boolean algebra of idempotents of R, which is a Stone space. A theorem of R. S. Pierce states that R can be represented as the ring of global sections of a sheaf of commutative rings on its Pierce spectrum (called the Pierce sheaf or representation), whose stalks are indecomposable rings (with respect to product decomposations). Diers showed that Pierce's theorem can be extended to any object in a locally finitely presentable category such that the opposite of the subcategory of finitely presentable objects is lextensive (called a locally indecomposable category). We shall see that a weak form of Pierce representation exists for any object in an extensive category. --------------FF260AA9AFA537FC9D7A1021 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit In a recent paper (TAC, Vol 4, 208-248)

On Generic Separable Objects, by Robbie Gates,

the author mentioned a well known "boolean algebraic structure of the summands of an object in an extensive category". This reminded me a paper I posted to my homepage last year (8/30/98, see the abstract below), in which the same boolean structure was reconstructed (at that time this was not "well known" to me), and was applied to define the Pierce topology for any extensive category, extending some results of Diers. The paper

Pierce Topologies of Extensive Categories

is available at Categorical Geometry Homepage at the following new (permanent, hopefully) address

http://www.geometry.net (or http://www.azd.com)

(The new service is a little bit slow, but offers more functions than the old one, so please be patient.)

Best wishes,

Zhaohua Luo
-----------------------------------------------------------------------------------------
Pierce Topologies of Extensive Categories

by Zhaohua Luo

Abstraction

An extensive category is a category with finite stable disjoint sums. In this note we show that each extensive category carries a natural subcanonical coherent Grothendieck topology defined by injections of sums. This Grothendieck topology is induced by a strict metric topology, which is a functor to the category of  Stone spaces. We call this metric topology the Pierce topology of the category, as it generalizes the classical Pierce spectrums of commutative rings. Recall that the Pierce spectrum of a commutative ring R is the spectrum of the Boolean algebra of idempotents of R, which is a Stone space. A theorem of R. S. Pierce states that R can be represented as the ring of global sections of a sheaf of commutative rings on its Pierce spectrum (called the Pierce sheaf or representation), whose stalks are indecomposable rings (with respect to product decomposations). Diers showed that Pierce's theorem can be extended to any object in a locally finitely presentable category such that the opposite of the subcategory of finitely presentable objects is lextensive (called a locally indecomposable category). We shall see that a weak form of Pierce representation exists for any object in an extensive category. --------------FF260AA9AFA537FC9D7A1021-- From cat-dist Wed Jan 13 16:54:34 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id PAA32367 for categories-list; Wed, 13 Jan 1999 15:01:11 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Message-Id: Date: Wed, 13 Jan 1999 18:20:59 +0000 (GMT) From: "Roy L. Crole" To: categories@mta.ca, types@cis.upenn.edu Subject: categories: Lectureships in Computer Science Mime-Version: 1.0 (generated by tm-edit 7.106) Content-Type: text/plain; charset=US-ASCII Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: LEICESTER UNIVERSITY DEPARTMENT OF MATHEMATICS AND COMPUTER SCIENCE LECTURESHIPS (GRADE A/B) IN COMPUTER SCIENCE (2 POSTS) Applications are invited for 2 permanent Lectureships in Computer Science in the Department of Mathematics and Computer Science at the University of Leicester. There is no restriction regarding the area of research and applicants with expertise in any area of Computer Science are welcomed. Both lectureships are tenable from 1 April 1999 or as soon as possible thereafter. The Department of Mathematics and Computer Science is divided into three groups: Computer Science, Pure Mathematics and Applicable Mathematics. The lectureships are intended to strengthen the Computer Science Group with regard to both teaching and research. The Computer Science Group is firmly research oriented and current activities are concentrated within three research areas: Logic, Algebra and Complexity; Theory of Distributed Systems; and Semantics. The successful applicants will be ambitious, able to develop their own research within a multi-faceted environment, and have a strong research record and potential. The new lecturers will be required to teach at undergraduate and postgraduate level, and to perform administrative duties as directed by the Head of Department. This is a superb opportunity for persons of energy, drive and ambition to assume rewarding roles and to establish themselves in a young, dynamic and rapidly developing department. Initial salary, dependent upon qualifications and experience, will be on the Lecturer Grade A or B scale UK pounds 16,655 to UK pounds 29,048 p.a. Candidates who are interested in the lectureships are invited, if they so wish, to contact Professor Iain Stewart, Head of Computer Science and Head of Department (telephone (+44) 116 252 3885, e-mail i.a.stewart@mcs.le.ac.uk) or Professor Rick Thomas, Deputy Head of Department (telephone (+44) 116 252 3411, email r.thomas@mcs.le.ac.uk), who will be pleased to discuss the Lectureships further. Information about all aspects of the Department is available from its World Wide Web pages [http://www.mcs.le.ac.uk]. Further particulars (which are also available on the World Wide Web) and application forms are available from the Personnel Office (Academic Appointments), University of Leicester, University Road, Leicester LE1 7RH, telephone (+44) 116 252 2758. The closing date for applications is 19 February 1999. From cat-dist Tue Jan 19 12:09:42 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id JAA11229 for categories-list; Tue, 19 Jan 1999 09:12:49 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Date: Mon, 18 Jan 1999 09:07:21 +0200 From: Eva Ullan Subject: categories: CSL'99 3rd CFP (Text & LaTex versions) X-Sender: evah@147.96.1.121 To: csl99org@eucmos.sim.ucm.es Message-id: MIME-version: 1.0 Content-type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mailserv.mta.ca id EAA08874 Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: ____________________________________________________ My apologies if you receive this more than once! ____________________________________________________ =================================== 3rd CALL FOR PAPERS -- CSL'99 Annual Conference of the European Association for Computer Science Logic September 20-25, 1999, Madrid, Spain =================================== __________________________________________________ IMPORTANT REMARK The proceedings volume will be available at the conference. In order to enable this, the DEADLINES for paper submission and notification of acceptance have been slightly MODIFIED w.r.t. the announcement made in the 1st call for papers. __________________________________________________ CSL is the annual conference of the European Association for Computer Science Logic (EACSL). The conference is intended for computer scientists whose research activities involve logic, as well as for logicians working on issues significant for computer science. Suggested, but not exclusive, topics of interest include: * abstract datatypes, * automated deduction, * categorical and topological approaches, * concurrency theory, * constructive mathematics, * database theory, * domain theory, * finite model theory, * lambda and combinatory calculi, * logical aspects of computational complexity, * logical foundations of programming paradigms, * linear logic, * modal and temporal logics, * model checking, * program logics and semantics, * program specification, transformation and verification, * rewriting, * symbolic computation. PROGRAM COMMITEE Samson Abramsky (Edinburgh, UK) Marc Bezem (Utrecht, The Netherlands) Peter Clote (Munich, Germany) Hubert Comon (Cachan, France) Jorg Flum (Freiburg i.Br., Germany) (co-chair) Harald Ganzinger (Saarbrucken, Germany) Neil Immerman (Amherst, USA) Neil Jones (Copenhagen, Denmark) Jan Maluszynski (Linkoping, Sweden) Michael Maher (Brisbane, Australia) Catuscia Palamidessi (Pennsylvania, USA) Mario Rodriguez-Artalejo (Madrid, Spain) (co-chair) Wolfgang Thomas (Aachen, Germany) Jerzy Tiuryn (Warsaw, Poland) Glynn Winskel (Aarhus, Denmark) Martin Wirsing (Munich, Germany) SCIENTIFIC PROGRAMME In addition to invited lectures and contributed papers, there will be two tutorials on theorem proving and rewriting techniques, scheduled on September 24 afternoon (Friday) and September 25 morning (Saturday), immediately after the main conference. ** September 20--24, 1999: Invited Lectures and Contributed Papers The list of invited speakers will include: Jose Luis Balcazar (Barcelona, Spain) Javier Esparza (Munich, Germany) Martin Grohe (Freiburg, Germany) Peter D. Mosses (Aarhus, Denmark) V. Vianu (San Diego, USA) ** September 24--25, 1999: CSL Tutorials Douglas Howe (Bell Labs, USA) Aart Middeldorp (Tsukuba, Japan) LOCAL ORGANIZING COMMITTEE J. Carlos Gonzalez-Moreno Teresa Hortala-Gonzalez Javier Leach-Albert (chair) Paco Lopez-Fraguas Fernando Saenz-Perez Eva Ullan EACSL BOARD Marc Bezem (Utrecht, President) Ian Stewart (Leicester, Vice-President) Clemens Lautemann (Mainz, Treasurer) Peter Hajek (Prague) Simone Martini (Udine) Christine Paulin (Paris) Moshe Vardi (Houston) Johann Makowsky (Haifa) Alexander Razborov (Moscow) EACSL homepage: http://www.dimi.uniud.it/~eacsl IMPORTANT DATES Paper submissions March 19, 1999 Notifications of acceptance May 31, 1999 Final version due: July 12, 1999 CSL'99 main conference September 20-24, 1999 CSL'99 Tutorials September 24-25, 1999 PAPER SUBMISSIONS Submitted papers must be written in English and describe work not previously published. They must not be submitted concurrently to a journal or to another conference. Papers authored or coauthored by members of the Program Committee are not allowed. Submissions must not exceed 15 pages, including title page, figures, and references. The title page must contain: title and authors; physical and e-mail addresses; telephone and (if available) fax number for each author; identification of corresponding author, if not the first author; an abstract of no more than 200 words; a list of keywords. Submissions must arrive by March 19, 1999, and notifications of acceptance will be sent by May 31, 1999. Authors are invited to send manuscripts by electronic mail, as uuencoded gzipped postcript files: * see the conference home page for instructions http://mozart.sip.ucm.es:1580/csl99 * or send an empty message with subject "submission information'' to csl99org@eucmos.sim.ucm.es Those authors without access to the facilities for electronic submission can alternatively submit five hardcopies to: Prof. Mario Rodriguez Artalejo, CSL'99 Departamento de Sistemas Informaticos y Programacion Facultad de Matematicas, Universidad Complutense de Madrid Av. Complutense s/n E-28040 Madrid Spain E-mail: mario@sip.ucm.es Phone: +34 91 3 94 45 12 Fax: +34 91 3 94 46 07 PUBLICATION Papers accepted by the Program Committee must be presented at the conference and will appear in a proceedings volume, to be published by Springer Verlag in the "Lecture Notes in Computer Science" series. The second refereeing round which was requested in previous CSL editions before accepting a paper for publication in the proceedings, has been suppressed following the decision taken by the EACSL membership meeting held during CSL'98 (Brno, Czech Republic, August 25th 1998). Final versions of accepted papers will be due by July 12, 1999. The format for camera-ready manuscripts will be that of Springer LNCS; instructions can be found in the LNCS home page at: http://www.springer.de/comp/lncs/index.html ADDITIONAL INFORMATION CSL'99 home page: http://mozart.sip.ucm.es:1580/csl99 CSL'99 local organization: csl99org@eucmos.sim.ucm.es %%%%%%%%%%%%%%%%%%%%%% LATEX VERSION %%%%%%%%%%%%%% % 2nd Call for Papers, CSL'99. % Last revision: September 24, 1998. \documentstyle{article} \oddsidemargin 6pt \evensidemargin 6pt \marginparwidth 90pt \marginparsep 10pt \topmargin -30pt \headheight 12pt \headsep 25pt \footheight 12pt \footskip 30pt \columnsep 10.5pt \columnseprule 0pt \addtolength{\oddsidemargin}{-2.3cm} \setlength{\textwidth}{20cm} %{18.7cm} \addtolength{\topmargin}{-1cm} \setlength{\textheight}{27cm} \pagestyle{empty} \begin{document} % Heading \begin{center} {\large \bf 3rd CALL FOR PAPERS -- CSL'99} \end{center} \begin{center} {\Large \bf Annual Conference of the }\\[1.5ex] {\Large \bf European Association for Computer Science Logic} \end{center} \begin{center} {\large \bf Madrid, Spain, September 20-25, 1999} \end{center} \vspace*{0.15in} % Left column \parbox[t]{6.5cm}{%6.3cm \footnotesize \noindent {\bf Program Committee:} \vspace*{0.05in} \begin{tabular}{l} Samson Abramsky (Edinburgh, UK)\\ Marc Bezem (Utrecht, The Netherlands)\\ Peter Clote (Munich, Germany)\\ Hubert Comon (Cachan, France)\\ J\"{o}rg Flum (Freiburg i.Br., Germany) \\ \hspace{1cm} ({\bf co-chair})\\ Harald Ganzinger (Saarbr\"{u}cken, Germany)\\ Neil Immerman (Amherst, USA)\\ Neil Jones (Copenhagen, Denmark)\\ Jan Maluszynski (Link\"{o}ping, Sweden)\\ Michael Maher (Brisbane, Australia)\\ Catuscia Palamidessi (Pennsylvania, USA)\\ Mario Rodr\'{\i}guez-Artalejo (Madrid, Spain) \\ \hspace{1cm} ({\bf co-chair})\\ Wolfgang Thomas (Aachen, Germany)\\ Jerzy Tiuryn (Warsaw, Poland)\\ Glynn Winskel (Aarhus, Denmark)\\ Martin Wirsing (Munich, Germany)\\ \end{tabular} \vspace*{0.10in} \noindent {\bf Invited Speakers:} \vspace*{0.05in} \begin{tabular}{l} Jos\'{e} Luis Balc\'{a}zar (Barcelona, Spain)\\ Javier Esparza (Munich, Germany)\\ Martin Grohe (Freiburg, Germany)\\ Peter D. Mosses (Aarhus, Denmark)\\ V. Vianu (San Diego, USA) \end{tabular} \vspace*{0.10in} \noindent {\bf Tutorialists:} \vspace*{0.05in} \begin{tabular}{l} Douglas Howe (Bell Labs, USA)\\ Aart Middeldorp (Tsukuba, Japan) \end{tabular} \vspace*{0.10in} \noindent {\bf Local Organizing Committee:} \vspace*{0.05in} \begin{tabular}{l} J. Carlos Gonz\'{a}lez-Moreno\\ Teresa Hortal\'{a}-Gonz\'{a}lez\\ Javier Leach-Albert ({\bf chair})\\ Paco L\'{o}pez-Fraguas\\ Fernando S\'{a}enz-P\'{e}rez\\ Eva Ull\'{a}n \end{tabular} \vspace*{0.10in} \noindent {\bf EACSL Board:} \vspace*{0.05in} \begin{tabular}{l} Marc Bezem (Utrecht, President)\\ Ian Stewart (Leicester, Vice-President)\\ Clemens Lautemann (Mainz, Treasurer)\\ Peter Hajek (Prague)\\ Simone Martini (Udine)\\ Christine Paulin (Paris)\\ Moshe Vardi (Houston)\\ Johann Makowsky (Haifa)\\ Alexander Razborov (Moscow)\\ \end{tabular} \vspace*{0.15in} \noindent {\bf EACSL homepage:} \vspace*{0.05in} \begin{tabular}{l} http://www.dimi.uniud.it/\~{}eacsl \end{tabular} \vspace*{0.15in} \noindent {\bf Important Dates:} \vspace*{0.05in} \begin{tabular}{l} Paper submissions: \\ ~~~~ March 19, 1999 \\ Notifications of acceptance: \\ ~~~~ May 31, 1999 \\ Final version due: \\ ~~~~ July 12, 1999 \\ CSL'99 main conference: \\ ~~~~ September 20-24, 1999 \\ CSL'99 Tutorials: \\ ~~~~ September 24-25, 1999 \end{tabular} } % \end{parbox} % Right column. No blank line here! \parbox[t]{5mm}{ \rule[-22.0cm]{0.2mm}{22.5cm} } %\end{parbox} \begin{minipage}[t]{11.0cm}%{11.5cm} \small {\bf Aims and Scope of the Conference:} {\bf CSL} is the annual conference of the {\em European Association for Computer Science Logic} (EACSL). The conference is intended for computer scientistswhose research activities involve logic, as well as for logicians working on issues significant for computer science. Suggested, but not exclusive, topics of interest include: abstract datatypes, automated deduction, categorical and topological approaches, concurrency theory, constructive mathematics, database theory, domain theory, finite model theory, lambda and combinatory calculi, logical aspects of computational complexity, logical foundations of programming paradigms, linear logic, modal and temporal logics, model checking, program logics and semantics, program specification, transformation and verification, rewriting, symbolic computation. \vspace*{0.12in} \noindent {\bf Scientific Programme:} In addition to invited lectures and contributed papers, there will be two tutorials on theorem proving and rewriting techniques, scheduled on September 24 afternoon (Friday) and September 25 morning (Saturday), immediately after the main conference. \vspace*{0.12in} \noindent {\bf Paper Submissions:} Submitted papers must be written in English and describe work not previously published. They must not be submitted concurrently to a journal or to another conference. Papers authored or co-authored by members of the Program Committee are not allowed. Submissions must not exceed 15 pages, including title page, figures, and references. The title page must contain: title and authors; physical and e-mail addresses; telephone and (if available) fax number for each author; identification of corresponding author, if not the first author; an abstract of no more than 200 words; a list of keywords. Submissions must arrive by {\bf March 19, 1999}, and notifications of acceptance will be sent by {\bf May 31, 1999}. Authors are invited to send manuscripts by electronic mail, as uuencoded gzipped postcript files (see the conference home page for instructions, or send an empty message with subject ``submission information'' to csl99org@eucmos.sim.ucm.es). Those authors without access to the facilities for electronic submission can alternatively submit {\em five hardcopies} to: \vspace*{0.05in} \begin{tabular}{l} Prof. Mario Rodr\'{\i}guez-Artalejo, CSL'99 \\ Departamento de Sistemas Inform\'{a}ticos y Programaci\'{o}n \\ Facultad de Matem\'{a}ticas, Universidad Complutense de Madrid \\ Av. Complutense s/n ~~~~~~~~~~ Phone: +34 91 3 94 45 12 \\ E-28040 Madrid ~~~~~~~~~~~~~~~~~ Fax: +34 91 3 94 46 07 \\ Spain ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ E-mail: mario@sip.ucm.es \end{tabular} \vspace*{0.12in} \noindent {\bf Publication:} Papers accepted by the Program Committee must be presented at the conference and {\bf will appear in a proceedings volume}, to be published by Springer Verlag in the ``Lecture Notes in Computer Science'' series. The second refereeing round which was requested in previous CSL editions before accepting a paper for publication in the proceedings, has been suppressed following the decision taken by the EACSL membership meeting held during CSL'98 (Brno, Czech Republic, August 25th 1998). Final versions of accepted papers will be due by {\bf July 12, 1999}. The format for camera-ready manuscripts will be that of Springer LNCS; instructions can be found in the LNCS home page at http://www.springer.de/comp/lncs/index.html. \vspace*{0.12in} \noindent {\bf Important Remark:} The proceedings volume will be available at the conference. In order to enable this, the deadlines for paper submission and notification of acceptance have been slightly modified w.r.t. the announcement made in the 1st call for papers. \vspace*{0.15in} \noindent {\bf Additional Information:} \vspace*{0.05in} \begin{tabular}{ll} CSL'99 home page: & http://mozart.sip.ucm.es:1580/csl99 \\ CSL'99 local organization: & E-mail: csl99org@eucmos.sim.ucm.es \end{tabular} \end{minipage} \end{document} From cat-dist Tue Jan 19 20:31:27 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id TAA21929 for categories-list; Tue, 19 Jan 1999 19:21:37 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f From: Myles Tierney Message-Id: <199901192121.QAA23193@cogito.math.uqam.ca> Subject: categories: Memorial To: categories@mta.ca Date: Tue, 19 Jan 1999 16:21:52 -0500 (EST) X-Mailer: ELM [version 2.4 PL24] MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: A Memorial Service, organized by Associated Press, will be held for Myles on Monday, January 25, at Newseum/NY, located at 580 Madison Ave. between 56th and 57th Streets. The Service begins at 10:30 a.m., and is open to all who wish to attend. Associated Press will try to make the Service available live on the Internet, at www.ap.org, for those unable to be in New York. Myles Tierney From cat-dist Wed Jan 20 12:24:50 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id JAA15646 for categories-list; Wed, 20 Jan 1999 09:29:38 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Message-Id: <22026.199901201228@craro.dcs.ed.ac.uk> X-Mailer: exmh version 2.0.2 2/24/98 To: categories@mta.ca Subject: categories: Paper Announcement Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Wed, 20 Jan 1999 12:28:53 +0000 From: Alex Simpson Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: The following paper is available by anonymous FTP or over the Web Computational Adequacy in an Elementary Topos We place simple axioms on an elementary topos which suffice for it to provide a denotational model of call-by-value PCF with sum and product types. The model is synthetic in the sense that types are interpreted by their set-theoretic counterparts within the topos. The main result characterises when the model is computationally adequate with respect to the operational semantics of the programming language. We prove that computational adequacy holds if and only if the topos is $1$-consistent (i.e. its internal logic validates only true $\Sigma^0_1$-sentences). This paper is to appear in the forthcoming proceedings of CSL 98. It is available from: http://www.dcs.ed.ac.uk/~als/Research/adequacy.ps.gz ftp://ftp.dcs.ed.ac.uk/pub/als/Research/adequacy.ps.gz Best wishes, Alex Simpson -- Alex Simpson, LFCS, Division of Informatics, University of Edinburgh Email: Alex.Simpson@dcs.ed.ac.uk Tel: +44 (0)131 650 5113 FTP: ftp.dcs.ed.ac.uk/pub/als Fax: +44 (0)131 667 7209 URL: http://www.dcs.ed.ac.uk/home/als From cat-dist Wed Jan 20 15:46:12 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id NAA28231 for categories-list; Wed, 20 Jan 1999 13:59:11 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f From: Koslowski Message-Id: <199901201640.RAA18661@lisa.iti.cs.tu-bs.de> Subject: categories: first reference to "dualizing object"? To: categories@mta.ca (categories list) Date: Wed, 20 Jan 1999 17:40:24 +0100 (MET) X-Mailer: ELM [version 2.4ME+ PL28 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: cat-dist@mta.ca Precedence: bulk Status: RO X-Status: Dear Colleagues, A referee attributed the notion of "dualizing object" in the context of *-autonomous to Grothendieck, but wasn't sure of the exact reference. Does somebody out there happen to know, where this was introduced first? Thank you very much. -- J"urgen Koslowski -- J"urgen Koslowski % If I don't see you no more in this world ITI % I meet you in the next world TU Braunschweig % and don't be late! koslowj@iti.cs.tu-bs.de % Jimi Hendrix (Voodoo Child) From cat-dist Wed Jan 20 21:27:16 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id UAA25994 for categories-list; Wed, 20 Jan 1999 20:07:40 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Date: Wed, 20 Jan 1999 14:56:56 -0400 (AST) From: TAC To: categories@mta.ca Subject: categories: TAC 1998 contents Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: cat-dist@mta.ca Precedence: bulk Status: RO X-Status: [note from moderator: it is quite possible that as result of a labour dispute at Mount Allison University the categories list may be dormant for an undetermined period. I will attempt to let you know and provide alternate access to the list if this happens; thanks for your patience. regards to all, Bob] Here is the table of contents and associated information for Theory and Applications of Categories for 1998. The Editors solicit high quality contributions. THEORY AND APPLICATIONS OF CATEGORIES ISSN 1201-561X Volume 4, 1998 Pasting in multiple categories Richard Steiner 1 Protomodularity, descent and semidirect products D. Bourn and G. Janelidze 37 A theory of enriched sketches F. Borceux, C. Quinteiro and J. Rosicky 47 Simplicial and categorical diagrams, and their equivariant applications Rudolf Fritsch and Marek Golasinski 73 A 2-categorical approach to change of base and geometric morphisms II A.Carboni, G.M.Kelly, D.Verity and R.J.Wood 82 The separated extensional Chu category Michael Barr 137 Applications of Peiffer pairings in the Moore complex of a simplicial group A. Mutlu and T. Porter 148 Freeness Conditions for 2-Crossed Modules and Complexes A. Mutlu and T. Porter 174 Geometric Construction of the Levi-Civita Parallelism Anders Kock 195 On Generic Separable Objects Robbie Gates 174 Copyright 1998 The Editors of Theory and Applications of Categories THEORY AND APPLICATIONS OF CATEGORIES (ISSN 1201-561X) will disseminate articles that significantly advance the study of categorical algebra or methods, or that make significant new contributions to mathematical science using categorical methods. The scope of the journal includes: all areas of pure category theory, including higher dimensional categories; applications of category theory to algebra, geometry and topology and other areas of mathematics; applications of category theory to computer science, physics and other mathematical sciences; contributions to scientific knowledge that make use of categorical methods. Articles appearing in the journal have been carefully and critically refereed under the responsibility of members of the Editorial Board. Only papers judged to be both significant and excellent are accepted for publication. The method of distribution of the journal is via the Internet tools WWW/ftp. The journal is archived electronically and in printed paper format. Subscription information: Individual subscribers receive (by e-mail) abstracts of articles as they are published. Full text of published articles is available in .dvi and Postscript format. Details will be e-mailed to new subscribers and are available by tt WWW/ftp. To subscribe, send e-mail to tac@mta.ca including a full name and postal address. For institutional subscription, send enquiries to the Managing Editor, Robert Rosebrugh, rrosebrugh@mta.ca. Information for authors: The typesetting language of the journal is TeX, and LaTeX is the preferred flavour. TeX source of articles for publication should be submitted by e-mail directly to an appropriate Editor. They are listed below. Please obtain detailed information on submission format and style files from the journal's WWW server at URL http://www.tac.mta.ca/tac/ or by anonymous ftp from ftp.tac.mta.ca in the directory pub/tac/info. You may also write to tac@mta.ca to receive details by e-mail. Editorial board: John Baez, University of California, Riverside: baez@math.ucr.edu Michael Barr, McGill University: barr@triples.math.mcgill.ca Lawrence Breen, Universite de Paris 13: breen@math.univ-paris13.fr Ronald Brown, University of North Wales: r.brown@bangor.ac.uk Jean-Luc Brylinski, Pennsylvania State University: jlb@math.psu.edu Aurelio Carboni, Universita dell Insubria: carboni@fis.unico.it P. T. Johnstone, University of Cambridge: ptj@pmms.cam.ac.uk G. Max Kelly, University of Sydney: kelly_m@maths.usyd.edu.au Anders Kock, University of Aarhus: kock@imf.au.dk F. William Lawvere, State University of New York at Buffalo: wlawvere@acsu.buffalo.edu Jean-Louis Loday, Universit e de Strasbourg: loday@math.u-strasbg.fr Ieke Moerdijk, University of Utrecht: moerdijk@math.ruu.nl Susan Niefield, Union College: niefiels@union.edu Robert Pare, Dalhousie University: pare@mscs.dal.ca Andrew Pitts, University of Cambridge: ap@cl.cam.ac.uk Robert Rosebrugh, Mount Allison University: rrosebrugh@mta.ca Jiri Rosicky, Masaryk University: rosicky@math.muni.cz James Stasheff, University of North Carolina: jds@charlie.math.unc.edu Ross Street, Macquarie University: street@macadam.mpce.mq.edu.au Walter Tholen, York University: tholen@mathstat.yorku.ca Myles Tierney, Rutgers University: tierney@math.rutgers.edu Robert F. C. Walters, University of Sydney: walters_b@maths.usyd.edu.au R. J. Wood, Dalhousie University: rjwood@mscs.dal.ca From cat-dist Wed Jan 20 21:27:46 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id UAA22690 for categories-list; Wed, 20 Jan 1999 20:09:12 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Message-Id: <36A63787.FFEC3A75@kestrel.edu> Date: Wed, 20 Jan 1999 12:07:35 -0800 From: Dusko Pavlovic X-Mailer: Mozilla 4.5 [en] (X11; U; SunOS 5.5.1 sun4u) X-Accept-Language: en Mime-Version: 1.0 To: Koslowski Cc: categories list Subject: categories: Re: first reference to "dualizing object"? References: <199901201640.RAA18661@lisa.iti.cs.tu-bs.de> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: > A referee attributed the notion of "dualizing object" in the context > of *-autonomous to Grothendieck, but wasn't sure of the exact > reference. Does somebody out there happen to know, where this was > introduced first? hi. there is probably a bit of duality in Grothendieck's TVS book. perhaps there is more in one of his functional analysis papers from the 50es, all referenced in the book. an even earlier source, with a hint of the chu construction, is George Mackey's work on barreled spaces, as pointed out to me by Bill Lawvere. -- dusko From cat-dist Sun Jan 24 22:22:40 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id VAA13951 for categories-list; Sun, 24 Jan 1999 21:18:02 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Date: Thu, 21 Jan 1999 15:20:59 -0500 (EST) From: Michael Barr To: Categories list Subject: categories: Juergen's question Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: I want to comment on Juergen's question. It is possible, I suppose, that Grothendieck used the phrase "dualizing object" somewhere, but as far as I am aware, he never did anything with them. It is not, after all, a difficult concept. He certainly never talked about "*-autonomous categories", although Grothendieck (and everyone else who ever gave it a thought) was surely aware that finite dimensional vectors spaces and finite abelian groups were such. If he ever isolated the concept as an interesting one, I am unaware of it and, in any case, I don't believe he ever pursued it (someone would surely have let me know by now). This mad insistence on giving Grothendieck credit for every fleeting idea he may (or even may not) have mentioned somewhere is a perfect example of how the star system (no pun intended) has permeated our consciousness. I am not, of course, blaming Grothendieck for any of this. In another instance, one of the best ideas I ever had has been named after Euler, who never heard of cohomology groups. Now, as I have said elsewhere, I was very much aware of the "pairs" of vector spaces used by the topological vector space theorists when I created the Chu construction. I believe that the sources I had seen stuck to the separated extensional case. They did not mention that this construction was originally due to Mackey, although I eventually (fairly recently) tracked it down. It was in his PhD thesis, in fact. I believe he did not stick to the separated extensional case. But neither he, nor anyone else I read talked about morphisms of pairs. In the se case, the morphisms are obvious. In the general case a bit less so. The duality was, of course, obvious and the main raison d'etre for the pairs. But, although it was obvious how to make the morphisms between two pairs into a vector space, no one seems to have even raised the question of making it into a pair. That it is possible and even easly struck me--and still strikes me--as an amazing bit of magic. Michael ------------------------------------------------------------------- History shows that the human mind, fed by constant accessions of knowledge, periodically grows too large for its theoretical coverings, and bursts them asunder to appear in new habiliments, as the feeding and growing grub, at intervals, casts its too narrow skin and assumes another... Truly the imago state of Man seems to be terribly distant, but every moult is a step gained. - Charles Darwin, from "The Origin of Species" From cat-dist Sun Jan 24 22:22:52 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id VAA16850 for categories-list; Sun, 24 Jan 1999 21:18:27 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Date: Thu, 21 Jan 1999 15:27:18 -0700 (MST) From: "Samuel B. Johnson" To: categories@mta.ca Subject: categories: Inquiry - Manhattan Street Problem Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: Inquiry to: categories list-serve subscribers In the mid- to late 70s there were meetings at Columbia University in New York of mathematicians interested in topos theory, which meetings I attended as a student of Peter Freyd. At one such meeting, someone proposed and solved the following problem, which I have since named The Manhattan Street Problem. (Note: it was NOT so named at the time.) Consider a large number of commuters, all traveling from south to north along two parallel highways. Connecting the two north-south highways are one (or more?) east-west linking streets, all of which are one way from west to east. The speed at which a commuter moves along any highway or street is a function of the number of users on that (part of that) highway or street, e.g., as more commuters who are initially on the western of the two north-south highways choose to leave and go over to the eastern of the two north-south highways, the speed of traffic on the western highway increases and the speed on the eastern highway decreases. The functions relating speed to number of users are not (necessarily) the same for each highway or street. (I think, however, that the most elegant solution would have a single function applicable to both highways and (all) street(s).) Each commuter chooses whether (and when, if there's more than one cross over street) to go over to the eastern highway in an attempt to minimize individual total travel time. Problem: Specify the speed controlling function(s), the number of crossing east-west roads and, if necessary, the distances, e.g., distance between eastern and western highways as a fraction of total north-south distance, or distance between various east-west roads, again presumably as a fraction of total north-south distance, such that: the system stabilizes, i.e., individual commuters cannot improve their time by changing their route, BUT the total travel time summed over all travelers is NOT a minimum. Thus, if such a solution is found, an omniscient, big brother traffic controller, by (randomly?) requiring some commuters to take a route slower than what he/she would individually choose, could thereby decrease (minimize?) travel time (hence air pollution?) for the whole commuting community. Plausibility argument that this might be possible: That the situation stabilizes seems intuitively plausible to me. That the stable situation might not minimize total travel time is suggested by the following: If the big brother traffic controller moves an individual from a too heavily traveled highway, the benefit flows to a large number of commuters left behind on that highway, which flows faster, even though the moved individual may be shunted over to a route slower for that individual. If anyone: a) remembers who presented and solved this problem at Columbia, or b) remembers the solution, or c) can point me toward where this might be solved in the literature, or d) can provide any other help, I would be extremely grateful. Samuel Johnson (sjohnson@mail.sjcsf.edu) Postscript: A solution would have (obvious?) implications for those who have great faith in the general applicability of free market mechanisms and Adam Smith's invisible hand for solving problems or finding best strategies from a society's point of view. From cat-dist Sun Jan 24 22:53:19 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id WAA19975 for categories-list; Sun, 24 Jan 1999 22:05:39 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Date: Fri, 22 Jan 1999 08:57:32 +0800 (CST) From: Pao-Ann Hsiung Message-Id: <199901220057.IAA10644@iis11.isd1> To: categories@mta.ca Subject: categories: SGM v1.1 Released Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: -------------------------------------------- State Graph Manipulators (SGM) New Version 1.1 Released!!! "http://www.iis.sinica.edu.tw/~eric/sgm/" -------------------------------------------- State Graph Manipulators (SGM) is a high-level state-graph manipulation tool for verification non-experts as well as experts. The tool has undergone further refining and testing. A much more stable version (v1.1) is now released for downloading. This version provides both a batch and an interactive user interface. The next version (v1.2) scheduled to be released around January 31, 1999 will have a flexible easy-to-use graphical user interface (GUI). Changes in v1.1 from v1.0 (1) Memory usage drastically reduced to 1/8th of that originally required in SGM v1.0. Memory leaks removed using Purify, a commercial program debugging tool from Rational Software. (2) SGM input language syntax modified to accomodate non-symmetrical system descriptions. Non-symmetrical systems can now be described! (3) A new manipulator (state-graph reduction technique) implemented: BIT (Bypass Internal-Transition). (4) Totally 5 application examples included with v1.1 distribution. (a) Fischer's Mutual Exclusion Protocol, (b) CSMA/CD Protocol, (c) Token Ring Network, (d) PATHO OS Priority-Based Task Execution, and (e) Bus Arbiter. (5) User manual updated to version 1.1. (6) Programming bugs/errors fixed. (7) Interactive user interface improved. (8) A graphical user interface has been developed and is being testing currently, it will be released in the next version SGM v1.2 around January 31, 1999. Visit URL: "http://www.iis.sinica.edu.tw/~eric/sgm/" to download SGM. SGM web site completely renewed for easier download and access. Authors: Dr. Pao-Ann Hsiung and Dr. Farn Wang Institute of Information Science Academia Sinica, Taipei, TAIWAN, R.O.C. E-mail: {eric,farn}@iis.sinica.edu.tw ----------------------------------------------------------------------------- Dr. Pao-Ann (Eric) Hsiung Institute of Information Science | E-MAIL: eric@iis.sinica.edu.tw Academia Sinica | TEL : +886-2-27883799 ext. 2453 Nankang, Taipei 115 | FAX : +886-2-27824814 TAIWAN, Republic of China. | URL : http://www.iis.sinica.edu.tw/~eric ----------------------------------------------------------------------------- From cat-dist Tue Jan 26 22:08:49 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id VAA23456 for categories-list; Tue, 26 Jan 1999 21:05:14 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Message-Id: <36AC2740.6AF02D32@kestrel.edu> Date: Mon, 25 Jan 1999 00:11:44 -0800 From: Dusko Pavlovic X-Mailer: Mozilla 4.5 [en] (Win98; U) X-Accept-Language: en,nl Mime-Version: 1.0 To: Michael Barr Cc: Categories list Subject: categories: Re: Juergen's question References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: cat-dist@mta.ca Precedence: bulk Status: RO X-Status: Michael Barr wrote: > I want to comment on Juergen's question. It is possible, I suppose, > that Grothendieck used the phrase "dualizing object" somewhere, but as > far as I am aware, he never did anything with them. It is not, after > all, a difficult concept. He certainly never talked about "*-autonomous > categories", although Grothendieck (and everyone else who ever gave it a > thought) was surely aware that finite dimensional vectors spaces and > finite abelian groups were such. If he ever isolated the concept as an > interesting one, I am unaware of it and, in any case, I don't believe he > ever pursued it (someone would surely have let me know by now). This > mad insistence on giving Grothendieck credit for every fleeting idea he > may (or even may not) have mentioned somewhere is a perfect example of > how the star system (no pun intended) has permeated our consciousness. I may have misunderstood, but I didn't think anyone even implied that Grothendieck could be credited with *-autonomous categories. Juergen was just asking about the history of the idea of dualizing object, which is just a part of that structure, and certainly predates it. The fact that an idea may have been in the air before it was captured in a structure does not have to decrease the merit of capturing it; on the contrary, it may also be thought of as a sign that it was an important idea, or that capturing it wasn't easy. The fact that Wiles was drawing upon a rich source of ideas does not devaluate his victory. > I am not, of course, blaming Grothendieck for any of this. In another > instance, one of the best ideas I ever had has been named after Euler, > who never heard of cohomology groups. This is a remarkable phenomenon, isn't it? Cartesius also knew nothing of Cartesian categories (or squares, or arrows...), and Frobenius could hardly recognize the logical form of his reciprocity... I think Etruscans had this religion, where they systematically attributed all victories to the ancestors, so that the soldiers wouldn't take things too personally. With kind regards, -- Dusko From cat-dist Tue Jan 26 22:08:49 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id VAA09728 for categories-list; Tue, 26 Jan 1999 21:06:19 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Date: Mon, 25 Jan 1999 09:30:08 +0100 (MET) From: "Pedicchio M. Cristina" To: categories@mta.ca Subject: categories: new mail address Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: cat-dist@mta.ca Precedence: bulk Status: RO X-Status: I inform that my e-mail is pedicchi@univ.trieste.it The previous address pedicchi@uts.univ.trieste.it, does not work any more; best regards Cristina Pedicchio From cat-dist Tue Jan 26 22:40:27 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id VAA00777 for categories-list; Tue, 26 Jan 1999 21:49:26 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Date: Mon, 25 Jan 1999 23:48:03 +0100 (MET) Message-Id: <199901252248.XAA27814@brics.dk> From: Uffe Henrik Engberg To: categories@mta.ca Subject: categories: May 3-7, 1999: Summer School in Semantics of Computation Mime-Version: 1.0 (generated by tm-edit 7.106) Content-Type: text/plain; charset=US-ASCII Sender: cat-dist@mta.ca Precedence: bulk Status: RO X-Status: SUMMER SCHOOL IN SEMANTICS OF COMPUTATION - organized by computer science research centres BRICS (Denmark) TUCS (Finland) IPA (Holland) - as part of the EEF series of summer schools, supported by the European Union. Place: BRICS, Aarhus University, Denmark. Time: May 3-7, 1999, with an informal get-together in the evening of May 2. Who Should Attend? The course is open to anyone interested. Prerequisites are an elementary knowledge of mathematics and computer science. A primary target group is PhD and other students. Grants: Grants for students to attend the school, covering accommodation and local costs, can be applied for (see below). As part of the application a recommendation letter is required from supervisor. Lecturers and Topics: Achim Jung (Birmingham): Domain Theory Luke Ong (Oxford): Correspondence between Operational and Denotational Semantics Bob Tennent (Queens, Canada): Denotational Semantics Jaap van Oosten (Utrecht): Category Theory in Semantics Andrzej Filinski (Aarhus): Semantics of Types (tentative) Each lecturer is to teach for 5-6 hours---a proportion of this time will be spent supervising students through exercises. How to Register Visit the web-site of the school: www.brics.dk/Activities/99/SemanticsSchool/ The registration fee is 1100 Danish kroner. This covers lunches, refreshments, social events and the banquet. A limited number of grants are available for students, covering registration and living expenses during the school, leaving only travel expenses to be paid. Applying for such a grant is also done by visiting the web site. To get more information, visit the Web-site of the school: www.brics.dk/Activities/99/SemanticsSchool/ From cat-dist Wed Jan 27 21:29:04 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id UAA12028 for categories-list; Wed, 27 Jan 1999 20:22:41 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Subject: categories: PSSL 70 -- Second Announcement To: categories@mta.ca, theory@cl.cam.ac.uk Date: Wed, 27 Jan 1999 15:29:11 +0000 (GMT) Cc: P.T.Johnstone@dpmms.cam.ac.uk X-Mailer: ELM [version 2.4 PL25] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Message-Id: From: "Dr. P.T. Johnstone" Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: PERIPATETIC SEMINAR ON SHEAVES AND LOGIC 70th meeting -- Second Announcement The 70th meeting of the PSSL will be held in Cambridge on the weekend of 27-28 February 1999. As usual, we welcome contributed talks on any aspect of category theory, sheaf theory or related areas of logic and computer science. As previously announced, this meeting will be a special one to celebrate the 60th birthday of Gavin Wraith, who has been involved with the Peripatetic Seminar since its inception in 1976. We therefore particularly welcome talks relating to areas in which Gavin has worked. Those intending to come to the meeting should complete the registration form below, and return it as soon as possible to . We shall attempt to arrange accommodation in College guest rooms (or, failing that, in local bed and breakfast establishments) for those who request it before 17 February. Lectures will take place in the Isaac Newton Institute, Clarkson Road, beginning at 9.30 on Saturday and ending by lunchtime on Sunday. An informal bread-and-cheese lunch will be provided on both days. Details of other arrangements, including a provisional programme, will be sent out about a week before the meeting to those who have registered. Peter Johnstone Martin Hyland Chris Mulvey ----------------------------------------------------------------------- PSSL 70 -- REGISTRATION FORM Name: Address: E-mail: I plan to attend the 70th meeting of the PSSL. *I should like to give a talk, lasting about minutes, entitled: *Please reserve accommodation for me for Friday/Saturday/Sunday night(s). *Delete if inappropriate. ------------------------------------------------------------------------ From cat-dist Thu Jan 28 04:59:04 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id DAA31240 for categories-list; Thu, 28 Jan 1999 03:55:10 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Date: Thu, 28 Jan 1999 18:40:37 +1100 (EST) Message-Id: <199901280740.SAA22067@algae.socs.uts.EDU.AU> To: categories@mta.ca Subject: categories: two questions about universal quantification From: Barry Jay Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: Can anyone help with the following two questions? Barry Jay Question 1 ~~~~~~~~~~ Has the following lemma been seen before? Lemma: If D is a cartesian closed category having all finite limits then so is its arrow category. Proof Finite limits in the arrow category are constructed pointwise. Arrows from a: A -> I to b: B-> J In the arrow category are given by commuting squares (all vertical lines are arrows pointing down) f A -----> B | | a| |b | | I -----> J u The object of such appropriate pairs (f,u) is given by the pullback E -----> A->B | | | | A->b | | I->J ---> A->J a->J The universal property follows directly. QED The proof uses a form of universal quantification over A. Similar constructions arise with the use of ends and dinatural transformations. I also used them aggresively in my paper on data categories (http://linus/~cbj/Publications/data_categories.ps.gz) to quantify over all paths through a tree. The lemma generalises to other functor categories over D provided there are sufficient limits in D to express all of the constraints. Question 2 ~~~~~~~~~~ The proof above shows how pullbacks and cartesian closure interact to provide a form of universal quantification. Call this new construction quantification by exponentiation. What is its expressive power? Discussion ~~~~~~~~~~ Universal quantification wrt an arrow f : X -> Y is usually given as a right adjoint to the functor D/Y --> D/X which pulls back along f. Call this quantification by adjunction. When it is specialised to a projection XxY ---> X then it can be thought of as quantification over the object Y. Quantification by exponentiation can be seen as supplying some of the ingredients necessary for this special case. For example, consider the equaliser E of two functions into an exponential: f,g : X --> (A->B) If the quantifier by adjunction exists for the projection XxA ---> X then E is given by applying it to the equaliser of the uncurried forms of f and g from XxA to B. Motivation ~~~~~~~~~~ One the one hand, this structure is weaker than that normally assumed, which may sometimes be a good thing. On the other hand, the power resulting from this combination of features may still be more than desired. Many models of computation assume both cartesian closure and and all finite limits but this is already more than we need to model the types of most languages, i.e. a type corresponding to one of the objects produced by quantification by exponentiation would have undecidable membership, so that values would need to come equipped with a proof of their membership. So (assuming that cartesian closure is a given) the question becomes whether there is a smaller class of limits which are good enough to model programming languages. One candidate is to work in an extensive category, in which only pullbacks along coproduct inclusions are presumed. A short argument shows that if Z has decidable equality then any cospan over it has a pullback. Actually, there is a rich, but under-explored class of pullbacks implied by this innocuous assumption. For example, the list functor preserves such pullbacks (this is not quite trivial). There may well be other, better candidates. I would be glad to hear of them. ************************************************************************* | Associate Professor C.Barry Jay, | | Reader in Computing Sciences Phone: (61 2) 9514 1814 | | Head, Algorithms and Languages Group, Fax: (61 2) 9514 1807 | | University of Technology, Sydney, e-mail: cbj@socs.uts.edu.au | | P.O. Box 123 Broadway, 2007, http://www-staff.socs.uts.edu.au/~cbj | | Australia. FISh homepage ... ~cbj/FISh | ************************************************************************* From cat-dist Thu Jan 28 20:38:40 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id TAA15035 for categories-list; Thu, 28 Jan 1999 19:17:40 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Subject: categories: Re: two questions about universal quantification Date: Thu, 28 Jan 1999 09:45:31 +0000 (GMT) To: categories@mta.ca In-Reply-To: <199901280740.SAA22067@algae.socs.uts.EDU.AU> from "Barry Jay" at Jan 28, 99 06:40:37 pm X-Mailer: ELM [version 2.4 PL25] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Message-Id: From: "Dr. P.T. Johnstone" Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: Barry Jay asked > Has the following lemma been seen before? > > Lemma: If D is a cartesian closed category having all finite limits > then so is its arrow category. This is a special case of the cartesian closedness of a category obtained by Artin glueing, which was covered in the Carboni--Johnstone paper (Math. Struct. Comp. Sci. 5 (1995), 441--459). (However, we don't claim any originality for it; it is implicit in Gavin Wraith's 1974 paper on Artin glueing.) Of course, the "glueing functor" in Barry's case is the identity on D. Peter Johnstone From cat-dist Thu Jan 28 21:19:00 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id TAA25223 for categories-list; Thu, 28 Jan 1999 19:15:52 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Message-Id: Date: Thu, 28 Jan 1999 09:36:34 +0000 (GMT) From: "Roy L. Crole" To: categories@mta.ca In-Reply-To: <199901280740.SAA22067@algae.socs.uts.EDU.AU> (message from Barry Jay on Thu, 28 Jan 1999 18:40:37 +1100 (EST)) Subject: categories: Re: two questions about universal quantification Mime-Version: 1.0 (generated by tm-edit 7.106) Content-Type: text/plain; charset=US-ASCII Sender: cat-dist@mta.ca Precedence: bulk Status: RO X-Status: >Question 1 >~~~~~~~~~~ >Has the following lemma been seen before? >Lemma: If D is a cartesian closed category having all finite limits >then so is its arrow category. If I've not misunderstood Barry's question 1, this is surely just the gluing or sconing lemma for the particular functor id_D : D -> D, where Glue(id_D) = arrow(D) Gluing along the identity gives a pleasant form for exponentials; the glued exponentials in Glue(G) for some G : C -> D collapse to the diagram in Barry's note. From cat-dist Thu Jan 28 22:38:46 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id VAA04029 for categories-list; Thu, 28 Jan 1999 21:36:55 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Date: Thu, 28 Jan 1999 11:37:05 +0800 (CST) From: eric@iis.sinica.edu.tw (Pao-Ann Hsiung) Message-Id: <199901280337.LAA09924@ccs1.iis.sinica.edu.tw> To: categories@mta.ca Subject: categories: CFP: PDPTA-99 Codesign Session Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: =========================================== S E C O N D C A L L F O R P A P E R S =========================================== SPECIAL SESSION ________________________________________________________________ "HARDWARE-SOFTWARE CODESIGN OF PARALLEL AND DISTRIBUTED SYSTEMS" ________________________________________________________________ "http://www.iis.sinica.edu.tw/~eric/pdpta99-codesign/" The 1999 International Conference on Parallel and Distributed Processing Techniques and Applications (PDPTA'99) June 28 - July 1, 1999 Monte Carlo Resort, Las Vegas, Nevada, USA A special session on the HARDWARE-SOFTWARE CODESIGN of parallel and distributed systems is being organized at PDPTA'99, which will be held in Las Vegas, Nevada, U.S.A., June 28 - July 1, 1999. Architectures supporting parallel and distributed computing include both hardware and software. The success of such architectures depends significantly on how the hardware and software interact. This in turn requires careful codesign approaches which include co-partitioning, scheduling, co-synthesis, co-simulation, and co-verification. Due to their complex behavior and structural restrictions, parallel and distributed systems present a greater challenge to codesign methodologies than conventional systems. Object-oriented modeling/design, formal specification/verification methods, graph-theoretic analysis, virtual prototyping, functional/structural partitioning are some promising techniques which can be employed for hardware-software codesign. Parallel and distributed processing is the computing trend and hardware-software codesign is the technique for supporting this trend. SESSION SCOPE: All hardware-software codesign related topics that deal with parallel and distributed systems are invited. Topics of interest include, but are not limited to, the following: * Specification/Modeling * Object-Oriented Technology * Co-design Methodologies/Tools * Parallel/Distributed Techniques * Co-partitioning * Virtual Prototyping * Related Software Synthesis * Rapid Prototyping * Related Hardware Synthesis * High-Assurance Systems * Co-simulation and Validation * IP / Virtual Components * Co-verification and Testing * Embedded/Real-Time Systems SUBMISSION OF PAPERS: To submit a paper to the special session, please do the following: (1) Prepare a manuscript in PDF/PostScript/Microsoft Word-7.0 format of maximum 7 pages: single-spaced, single-column, US-Letter/A4 size, with title, authors, affiliations, e-mail addresses, and a 100-word abstract on the first page. (2) Send an ascii-text e-mail with the paper title and the corresponding author's name, mailing address, e-mail address, and telephone/fax numbers. (3) E-mail the above two to: "eric@iis.sinica.edu.tw". If electronic submission is not possible, please mail the above to the following address: Dr. Hsiung, Pao-Ann (Mailbox A-38) Institute of Information Science Academia Sinica No. 128, Sec. 2, Academic Road Nankang, Taipei 115, TAIWAN, R.O.C. (4) Important Dates: Submission Deadline: March 1, 1999 Paper Notification: April 1, 1999 Camera-Ready papers: May 1, 1999 Pre-Registration: May 1, 1999 PDPTA'99 Conference: June 28-July 1, 1999 (5) A minimum of 6 and a maximum of 24 papers will be accepted for the special session. All submissions will be reviewed by at least 2 referees. Papers must not have been previously published or currently submitted for publication elsewhere. Pre-registration at the conference is a must for all accepted papers to be published in the proceedings. All accepted papers must be presented at PDPTA'99, Las Vegas, Nevada, U.S.A. PUBLICATION: The conference proceedings will be published by CSREA Press (ISBN). It will be a multivolume set. The proceedings will be available at the conference. All accepted papers will also be considered for journal publication (soon after the conference). ORGANIZERS/SPONSORS: A number of university faculty members and their staff in cooperation with the Monte Carlo Resort (Conference Division, Las Vegas ), will be organizing the conference. The conference is sponsored by the Computer Science Research, Education, and Applications Press (CSREA: USA Federal EIN # 58-2171953) in cooperation with the National Supercomputing Center for Energy and the Environment (Department of Energy, USA), The International Association for Mathematics and Computers in Simulation (IMACS), The International Technology Institute (ITI), The Java High Performance Computing research group (JHPC; www.jhpc.org), the Computer Vision Research and Applications Tech. (CVRA), developers of high-performance machines and systems (pending) and other related computer associations (pending.) LOCATION OF CONFERENCE: The conference will be held in the Monte Carlo Resort hotel, Las Vegas, Nevada, USA. This is a mega hotel with excellent conference facilities and over 3000 rooms. The hotel is minutes from the Las Vegas airport with free shuttles to and from the airport. This hotel has many vacation and recreational attractions, including: waterfalls, casino, spa, pools & kiddie pools, sunning decks, Easy River water ride, wave pool with cascades, lighted tennis courts, health spa (with workout equipment, whirlpool, sauna, ...), arcade virtual reality game rooms, nightly shows, snack bars, a number of restaurants, shopping area, bars, ... Many of these attractions are open 24 hours a day and most are suitable for families and children. The negotiated hotel's room rate for conference attendees is very reasonable ($79 + tax) per night (no extra charge for double occupancy) for the duration of the conference. The hotel is within walking distance from most other Las Vegas attractions (major shopping areas, recreational destinations, fine dining and night clubs, free street shows, ...). For the benefit of our international colleagues: the state of Nevada neighbors with the states of California, Oregon, Idaho, Utah, and Arizona. Las Vegas is only a few driving hours away from other major cities, including: Los Angeles, San Diego, Phoenix, Grand Canyon, ... EXHIBITION: An exhibition is planned for the duration of the conference. We have reserved 20+ exhibit spaces. Interested parties should contact H. R. Arabnia (address is given below). All exhibitors will be considered to be the co-sponsors of the conference. Each exhibitor will have the opportunity to include a two-page description of their latest products in the conference proceedings (if submitted by May 1, 1999). MEMBERS OF PROGRAM & ORGANIZING COMMITTEES: The Program Committee is currently being formed. Those interested in joining the Program Committee should email H. R. Arabnia (hra@cs.uga.edu) the following information: Name, affiliation and position, complete mailing address, email address, tel/fax numbers, a short biography together with research interests. SESSION CHAIR/ORGANIZER: Address: Dr. Pao-Ann Hsiung Institute of Information Science Academia Sinica No. 128, Sec. 2, Academic Road Nankang, Taipei 115, TAIWAN, R.O.C. E-mail: eric@iis.sinica.edu.tw Tel. : +886-2-27883799 Fax : +886-2-27824814 URL : http://www.iis.sinica.edu.tw/~eric/pdpta99-codesign/ CONFERENCE CONTACT: Hamid R. Arabnia The University of Georgia Department of Computer Science 415 Graduate Studies Research Center Athens, Georgia 30602-7404, U.S.A. Tel: (706) 542-3480 Fax: (706) 542-2966 E-mail: hra@cs.uga.edu URL: http://www.jhpc.org/pdpta/ From cat-dist Thu Jan 28 22:45:06 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id VAA17939 for categories-list; Thu, 28 Jan 1999 21:42:10 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f From: Jose Meseguer Date: Thu, 28 Jan 1999 17:17:38 -0800 (PST) Message-Id: <199901290117.RAA16611@cyrano.csl.sri.com> To: categories@mta.ca Subject: categories: Maude 1.00 Release Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: The Maude system, its documentation, a collection of examples, and a list of related papers are available (free of charge) on the web at http://maude.csl.sri.com Maude is a high-performance reflective language and system supporting both equational and rewriting logic specification and programming for a wide range of applications. Maude has been influenced in important ways by the OBJ3 language, which can be regarded as an equational logic sublanguage. Besides supporting equational specification and programming, Maude also supports rewriting logic computation. Rewriting logic is a logic of concurrent change that can naturally deal with state and with concurrent computations. It has good properties as a general semantic framework for giving executable semantics to a wide range of languages and models of concurrency. In particular, it supports very well concurrent object-oriented computation. The same reasons making rewriting logic a good semantic framework make it also a good logical framework, that is, a metalogic in which many other logics can be naturally represented and executed. Maude supports in a systematic and efficient way logical reflection. This makes Maude remarkably extensible and powerful, supports an extensible algebra of module composition operations, and allows many advanced metaprogramming and metalanguage applications. Indeed, some of the most interesting applications of Maude are metalanguage applications, in which Maude is used to create executable environments for different logics, theorem provers, languages, and models of computation. %%% Please, excuse the inconvenience if you received multiple copies. From cat-dist Fri Jan 29 04:26:50 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id DAA28768 for categories-list; Fri, 29 Jan 1999 03:36:40 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Date: Thu, 28 Jan 1999 23:13:03 -0600 (CST) From: Hongseok Yang To: categories@mta.ca Subject: categories: Pullback perserving functor Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: cat-dist@mta.ca Precedence: bulk Status: RO X-Status: Would someone let me know the answer and the proof or counter example of the following question? Suppose the category C has a pullback for every pair of morphism (f : X -> Y, g : W -> Y). Let K be the full subcategory of the functor category Func(C,Set) whose objects are pullback perserving functors. Is K ccc? (If so, how I can show this?) Thanks, Hongseok From cat-dist Fri Jan 29 23:04:59 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id WAA14762 for categories-list; Fri, 29 Jan 1999 22:19:29 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Date: Fri, 29 Jan 1999 08:08:26 -0500 (EST) From: Michael Barr To: Categories list Subject: categories: Barry Jay's question Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: Unless I am missing something, it seems to me that for any CCC C with finite limits and any finite category I, the functor category C^I is a CCC. You can also replace finite by any cardinal if you do it in both places. The argument is roughly this. Let |I| denote the discrete category with the objects of I. The inclusion |I| --> I induces U: C^I --> C^{|I|} and the limits imply the existence of a right adjoint R of U. Since U also preserves limits, the cotriple (UR,e,d) preserves finite limits. It is easy to see that U is cotripleable and that C^{|I|} is a CCC and, hence, so is C^I. For define A -o RC = R(UA -o C). For a general object B, the line B --> URB ==> URURB is an equalizer and you can define A -o B as the equalizer of A -o URB ==> A -o URURB. Michael ------------------------------------------------------------------- History shows that the human mind, fed by constant accessions of knowledge, periodically grows too large for its theoretical coverings, and bursts them asunder to appear in new habiliments, as the feeding and growing grub, at intervals, casts its too narrow skin and assumes another... Truly the imago state of Man seems to be terribly distant, but every moult is a step gained. - Charles Darwin, from "The Origin of Species" From cat-dist Fri Jan 29 23:05:04 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id WAA05429 for categories-list; Fri, 29 Jan 1999 22:17:26 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f To: categories@mta.ca Subject: categories: Conference Announcement BCTCS 15 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-MD5: 6WdDOrOM9Ouku2aXaPdeew== Message-Id: From: "John G. Stell" Date: Fri, 29 Jan 1999 10:46:24 +0000 Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: ___________________________________________________________________________ CALL FOR CONTRIBUTIONS AND PARTICIPATION 15th British Colloquium for Theoretical Computer Science (BCTCS 15) 14th - 16th April 1999 at Keele University Supported by EPSRC and the London Mathematical Society ___________________________________________________________________________ INVITED SPEAKERS: Wan Fokkink (Swansea) Martin Hofmann (Edinburgh) Bill McColl (Oxford) Ian Pratt (Manchester) David Pym (QMW, London) Glynn Winskel (Aarhus) Mike Worboys (Keele) ___________________________________________________________________________ CONTRIBUTED TALKS Contributions are sought on any aspect of theoretical computer science. Research areas within the scope of BCTCS include, but are not limited to, the following list: Concurrency, types, semantics, formal methods, computational complexity, algorithms, discrete mathematics, proof theory and logic, artificial intelligence, database theory, theorem proving, symbolic computation and experimental work. This year for the first time, authors will have the option to submit papers based on their talks to a special issue of the Journal of Universal Computer Science. However, the meeting will retain its informal character, and it will still be possible for researchers to give a presentation at the meeting but not have their paper considered for publication. Submission of papers for publication will take place at some stage after the meeting. Besides talks from established researchers, BCTCS meetings provide a forum for young researchers who may wish to give a presentation but who may feel that the body of their work is not yet substantial enough for publication. ___________________________________________________________________________ SUPPORT FOR POSTGRADUATE STUDENTS A limited number of fully funded places are available to postgraduate students who are supported by EPSRC. For other students there is a SPECIAL REDUCED RATE for the meeting, and some additional financial support may be available in special cases. ___________________________________________________________________________ FURTHER DETAILS Further details, including registration forms, prices, and forms for submission of contributed talks, are available from the BCTCS15 web page: http://www.keele.ac.uk/depts/cs/Announcements/bctcs/ The web page also has links to previous BCTCS meetings, which provide a useful guide to the wide range of topics which have been covered by past contributions. BCTCS15 is organized by John Stell, who can be contacted by email: john@cs.keele.ac.uk or at: Department of Computer Science, Keele University, Keele, Staffs, U. K., ST5 5BG. ___________________________________________________________________________ From cat-dist Fri Jan 29 23:05:04 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id WAA03223 for categories-list; Fri, 29 Jan 1999 22:22:07 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Subject: categories: Re: Pullback preserving functor Date: Fri, 29 Jan 1999 15:35:47 +0000 (GMT) To: categories@mta.ca In-Reply-To: from "Hongseok Yang" at Jan 28, 99 11:13:03 pm X-Mailer: ELM [version 2.4 PL25] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Message-Id: From: "Dr. P.T. Johnstone" Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: > Would someone let me know the answer and the proof or counter example of > the following question? > > Suppose the category C has a pullback for every pair of morphism > (f : X -> Y, g : W -> Y). Let K be the full subcategory of the functor > category Func(C,Set) whose objects are pullback perserving functors. > Is K ccc? (If so, how I can show this?) The answer is no. First note that K is closed under products in the functor category. Also, it contains all the representable functors; so, if it were cartesian closed, the exponential G^F would have to be given by G^F(c) \cong nat((c,-),G^F) \cong nat((c,-)\times F,G) i.e. K would have to be closed under exponentials in [C,Set]. However, it isn't in general. For a simple counterexample, let C be the category with five objects a,b,c,d,e and six non-identity morphisms a --> b, a --> c, b --> d, c --> d, a --> d, a --> e ; note that C has just one nontrivial pullback square a -----> b | | | | v v c -----> d Let F be the functor given by F(a) = F(b) = F(c) = F(d) = \emptyset, F(e) = {*}, and let G be F + F. Then (taking the above definition of G^F) G^F(a) has two elements, but G^F(b), G^F(c) and G^F(d) are singletons. Peter Johnstone From cat-dist Fri Jan 29 23:05:08 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id WAA10106 for categories-list; Fri, 29 Jan 1999 22:17:59 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Subject: categories: Generalized Enrichment To: categories@mta.ca Date: Fri, 29 Jan 1999 12:29:26 +0000 (GMT) Cc: T.Leinster@dpmms.cam.ac.uk (Tom Leinster) X-Mailer: ELM [version 2.4 PL25] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Message-Id: From: Tom Leinster Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: The following is now available, at http://www.dpmms.cam.ac.uk/~leinster/ Generalized Enrichment for Categories and Multicategories In this paper we answer the question: `what kind of a structure can a general multicategory be enriched in?' (Here `general multicategory' is used in the sense of the author, Burroni or Hermida.) The answer is, in a sense to be made precise, that a multicategory of one type can be enriched in a multicategory of the type one level up. In particular, we will be able to speak of a T_n-multicategory enriched in a T_{n+1}-multicategory, where T_n is the monad expressing the pasting-together of n-opetopes. The answer for general multicategories reduces to something surprising in the case of ordinary categories: a category may be enriched in an `fc-multicategory', a very general kind of 2-dimensional structure encompassing monoidal categories, plain multicategories, bicategories and double categories. It turns out that fc-multicategories also provide a natural setting for the bimodules construction. We also explore enrichment for some multicategories other than just categories. An extended application is given: the relaxed multicategories of Borcherds and Soibelman are explained in terms of enrichment. Tom Leinster PS - There's been the odd problem in the past with the web address; if it doesn't work, try substituting "can" for "www", or send me an email. From cat-dist Fri Jan 29 23:09:59 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id WAA10073 for categories-list; Fri, 29 Jan 1999 22:20:37 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Date: Fri, 29 Jan 1999 09:51:13 -0500 (EST) From: F W Lawvere Reply-To: wlawvere@ACSU.Buffalo.EDU To: categories@mta.ca Subject: categories: Re: Pullback perserving functor In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: Whether or not these functors form a cartesian-closed category depends strongly on the nature of the domain category. For example, if the domain category is an abelian category as opposed to it being a pretopos. Related matters are discussed in the recent paper by Borceux and Pedicchio and the papers there cited: Left-exact presheaves on a small pretopos, Journal of Pure and Applied Algebra, vol. 135, no. 1, 4 Febr. 1999, pp 9 - 22. ******************************************************************************* F. William Lawvere Mathematics Dept. SUNY wlawvere@acsu.buffalo.edu 106 Diefendorf Hall 716-829-2144 ext. 117 Buffalo, N.Y. 14214, USA ******************************************************************************* On Thu, 28 Jan 1999, Hongseok Yang wrote: > > Would someone let me know the answer and the proof or counter example of > the following question? > > Suppose the category C has a pullback for every pair of morphism > (f : X -> Y, g : W -> Y). Let K be the full subcategory of the functor > category Func(C,Set) whose objects are pullback perserving functors. > Is K ccc? (If so, how I can show this?) > > Thanks, > Hongseok > > > From cat-dist Sun Jan 31 01:00:18 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id VAA20130 for categories-list; Sat, 30 Jan 1999 21:24:49 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Message-Id: <199901301048.LAA13272@portofix.ida.liu.se> Date: Sat, 30 Jan 1999 11:48:10 +0100 (MET) From: Lars Lindqvist Reply-To: Lars Lindqvist Subject: categories: Reading advise on bicategory theory To: categories@mta.ca MIME-Version: 1.0 Content-Type: TEXT/plain; charset=us-ascii Content-MD5: BgezVXG1sA+vcYpKeDh0bQ== X-Mailer: dtmail 1.2.1 CDE Version 1.2.1 SunOS 5.6 sun4m sparc Sender: cat-dist@mta.ca Precedence: bulk Status: RO X-Status: Hi, I am looking for advise on suitable litterature for a beginner in bicategory-theory. The litterature I have found so far is: Kelly, Street Review of the elements of 2-categories Borceux Handbook of categorical algebra 1 I have also ordered the following article: Benabou Introduction to bicategories So far I have only read Borceux's book but it contains mainly definitions. In particular I have difficulties understanding the need for (and consequences of) the coherence axioms associated with the natural isomorphisms expressing the associativity and identity 'axioms'. /Lars Lindqvist From cat-dist Sun Jan 31 21:18:49 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id UAA25555 for categories-list; Sun, 31 Jan 1999 20:24:21 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Date: Sun, 31 Jan 1999 10:20:19 -0500 (EST) From: John R Isbell To: categories@mta.ca Subject: categories: Re: Reading advise on bicategory theory In-Reply-To: <199901301048.LAA13272@portofix.ida.liu.se> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: cat-dist@mta.ca Precedence: bulk Status: RO X-Status: Lars, I would guess that you will get more advice than you can use. Here is my nickel's worth. The matter of coherence is wide open. There is a paper of Yanofsky accepted for publication in JPAA which investigates higher dimensional categories with no coherence assumptions at all -- this coming after a lot of work on weakened coherence. Benabou's basic point was that naturally arising 2-dimensional categories are not quite 2-categories and don't seem to suffer from it. Avoid getting knotted in coherence questions, especially in 1999. _____________________________ John R. Isbell ji2@buffalo.edu or ji2@acsu.buffalo.edu Homepage: www.unipissing.ca/topology/z/a/a/a/05.htm _________________________________________________ | | | Der Mensch ist nur da ganz Mensch, wo er spielt. | | | | -- Friedrich Schiller | |_________________________________________________ | On Sat, 30 Jan 1999, Lars Lindqvist wrote: > Hi, > > I am looking for advise on suitable litterature for a beginner in > bicategory-theory. The litterature I have found so far is: > > Kelly, Street Review of the elements of 2-categories > Borceux Handbook of categorical algebra 1 > > I have also ordered the following article: > > Benabou Introduction to bicategories > > So far I have only read Borceux's book but it contains mainly > definitions. In particular I have difficulties understanding > the need for (and consequences of) the coherence axioms > associated with the natural isomorphisms expressing the > associativity and identity 'axioms'. > > /Lars Lindqvist > > > From cat-dist Sun Jan 31 21:20:02 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id UAA30332 for categories-list; Sun, 31 Jan 1999 20:30:08 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f From: Koslowski Message-Id: <199902010000.BAA28439@lisa.iti.cs.tu-bs.de> Subject: categories: paper announcement To: categories@mta.ca (categories list) Date: Mon, 1 Feb 1999 01:00:07 +0100 (MET) X-Mailer: ELM [version 2.4ME+ PL28 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: cat-dist@mta.ca Precedence: bulk Status: RO X-Status: A heavily revised version of my paper "Beyond the Chu-construction" is now available from my home page: http://www.iti.cs.tu-bs.de/~koslowj/RESEARCH/ It will eventually be published in Applied Categorical Structures. I have not attempted to attribute the term "dualizing object" to anyone in particular. The open problem of an earlier version, as to whether Cauchy-complete bicategories of interpolads inherit local *-autonomy from their base, has been answered affirmatively. Here is the abstract: Starting from symmetric monoidal closed (= autonomous) categories, Po-Hsiang Chu showed how to construct new *-autonomous categories, i.e., autonomous categories that are self-dual because of a dualizing object. Recently, Michael Barr extended this to the non-symmetric, but closed, case, utilizing monads and modules between them. Since these notions are well-understood for bicategories, we introduce a notion of local *-autonomy for these that implies closedness and, moreover, is inherited when forming bicategories of monads and of interpolads. Since the initial step of Barr's construction also carries over to the bicategorical setting, we recover his main result as an easy corollary. Furthermore, the Chu-construction at this level may be viewed as a procedure for turning the endo-1-cells of a closed bicategory into the objects of a new closed bicategory, and hence conceptually is similar to constructing bicategories of monads and of interpolads. Best regards, -- J"urgen -- J"urgen Koslowski % If I don't see you no more in this world ITI % I meet you in the next world TU Braunschweig % and don't be late! koslowj@iti.cs.tu-bs.de % Jimi Hendrix (Voodoo Child) From cat-dist Mon Feb 1 01:32:51 1999 Received: (from Majordom@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id AAA19723 for categories-list; Mon, 1 Feb 1999 00:38:33 -0400 (AST) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f Date: Sun, 31 Jan 1999 17:28:51 -0800 (PST) From: james dolan Message-Id: <199902010128.RAA04546@math.ucr.edu> To: categories@mta.ca Subject: categories: Re: Reading advise on bicategory theory Sender: cat-dist@mta.ca Precedence: bulk Status: RO X-Status: john isbell writes: -The matter of coherence is wide open. There is a paper of Yanofsky -accepted for publication in JPAA which investigates higher dimensional -categories with no coherence assumptions at all -- this coming after a -lot of work on weakened coherence. Benabou's basic point was that -naturally arising 2-dimensional categories are not quite 2-categories -and don't seem to suffer from it. Avoid getting knotted in coherence -questions, especially in 1999. what does "no coherence assumptions at all" mean in this context? does it mean that yanofsky is studying what i call "coarse n-categories", defined recursively as categories enriched over the cartesian closed category where the objects are the coarse [n-1]-categories and the morphisms are the enriched natural isomorphism classes of enriched functors? coarse n-categories are interesting but they're obviously not the whole story; for example it's straightforward to define the "fundamental coarse n-groupoid" of a space, but it's indeed a rather coarse invariant of the homotopy type.