From MAILER-DAEMON Fri May 18 09:39:42 2007 Date: 18 May 2007 09:39:42 -0300 From: Mail System Internal Data Subject: DON'T DELETE THIS MESSAGE -- FOLDER INTERNAL DATA Message-ID: <1179491982@mta.ca> X-IMAP: 1169056715 0000000103 Status: RO This text is part of the internal format of your mail folder, and is not a real message. It is created automatically by the mail system software. If deleted, important folder data will be lost, and it will be re-created with the data reset to initial values. From rrosebru@mta.ca Mon Jan 1 23:18:28 2007 -0400 Mime-Version: 1.0 (Apple Message framework v752.2) Message-Id: Content-Type: multipart/alternative; boundary=Apple-Mail-3-422131662 To: Categories Subject: categories: A book From: Ross Street Date: Tue, 2 Jan 2007 14:18:12 +1100 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII; format=flowed Status: O X-Status: X-Keywords: X-UID: 39 A few copies of the book Title: Quantum Groups: A Path to Current Algebra Series: Australian Mathematical Society Lecture Series (No. 19) arrived in my office today by courier from Cambridge University Press. So it really does exist. Please look at the site for further details. Best wishes, Ross From rrosebru@mta.ca Tue Jan 2 08:11:08 2007 -0400 From: "Ronnie Brown" To: Subject: categories: Re: What is needed for an online journal Date: Tue, 2 Jan 2007 12:10:20 -0000 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Status: O X-Status: X-Keywords: X-UID: 40 Mike Barr has put his finger on the key points: papers are needed not = just as a contribution to the advancement of knowledge but also for = career prospects and the awarding of research grants, which are also = related to career prospects. Further there are the notions of `impact = factor' of various journals, and that of citation indices.=20 On the last, some Governments take the line that a journal to be rated = for research promotion has to be on the list of the Institute for = Scientific Information (ISI: http://scientific.thomson.com/). It is = possible that the UK Government, in moving to using `metrics' for = research impact, will take this line. A search of the ISI list shows = that it has of course journals of major publishers and of national = academic institutions, and that it claims to have a procedure for = adding journals to their list. But the operation of the listing is based = on the idea that not all journals need to be listed, in order to assess = significance. TAC is not on the list, and I think neither is NYJM, = Cahier. It is also difficult to get on the list, as evidence from = editors shows, and there is no evidence of an academic input to the ISI = procedures. The organisation is a commercial organisation, which has = some control of scientific information.=20 Eugene Garfield writes in 2004:=20 Garfield, Eugene] ARE YOU SUGGESTING ISI COVER THE LOWEST IMPACT = JOURNALS AND PASS LESS ATTENTION TO THE HIGHEST?=20 [Garfield, Eugene] WE CANNOT CONTROL HOW THE DATA IS USED. I HAVE DONE = MY BEST TO PREVENT ITS ABUSE BUT I HAVE NO POWER TO CONTROL IT.=20 Perhaps also mathematicians in research assessment forget the long time = scale of the impact of new ideas. It is very easy to rate work which is = related to famous problems. It is less easy to rate work which opens a = new range of ideas, as has category theory, for example. I am grateful = to David Corfield for pointing out a quotation from Rota's `Indiscrete = thoughts' p.48:=20 ``What can you prove with exterior algebra that you cannot prove without it?" Whenever you hear this question raised about some new piece of mathematics, be assured that you are likely to be in the presence of something important. In my time, I have heard it repeated for random variables, Laurent Schwartz' theory of distributions, ideles and Grothendieck's schemes, to mention only a few. A proper retort might be: ``You are right. There is nothing in yesterday's mathematics that could not also be proved without it. Exterior algebra is not meant to prove old facts, it is meant to disclose a new world. Disclosing new worlds is as worthwhile a mathematical enterprise as proving old conjectures. There is a discussion of ISI and related issues of impact factors etc in = http://en.wikipedia.org/wiki/Institute_for_Scientific_Information Ronnie Brown www.bangor.ac.uk/r.brown From rrosebru@mta.ca Wed Jan 3 05:46:12 2007 -0400 Mime-Version: 1.0 (Apple Message framework v752.2) Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Content-Transfer-Encoding: 7bit From: Marino Miculan Subject: categories: Re: What is needed for an online journal Date: Wed, 3 Jan 2007 10:46:07 +0100 To: categories Status: O X-Status: X-Keywords: X-UID: 41 On 31/dic/06, at 21:30, John Baez wrote: >> What about having an editorial board, which would look at papers >> on the >> arxiv, say, have them reviewed and revised, and then put them back >> on the >> arxiv in final form, and listed elsewhere as having been through that >> process and "blessed" so to speak by the editorial board? > > This is what many journals do, after someone submits the paper. > > For example, with Advances in Theoretical and Mathematical Physics, > you submit a paper merely by sending them its arXiv number; when > it's accepted you prepare a version in their preferred format and this > gets put on the arXiv. Another, and quite successful, example is the Journal of High Energy Physics (http://jhep.sissa.it), an on-line journal which I have worked for at its beginnings, many years ago (back in 1997). Papers can be submitted by indicating an arXiv number, or by uploading a (PDF, LaTeX...) file. The editorial procedure is fully automatized, in the sense that it is fully operated on the web site, with minimal human intervention. This allows to reduce maintenance costs, and to speed up the publishing process of one magnitude (the average time from submission to publishing is something less than 2 months, which is mostly due to the referees). Once, accepted papers were freely available online from JHEP site; nowadays, these are available online through IOP's Electronic Journals service; but I guess that papers are still available for free (at least for some time), or at a reasonable price. Ten years ago, JHEP was started by an academic consortium as a spontaneous answer to the (already!) outrageously increasing prices of the main journals in the HEP field, especially Nuclear Physics B (which is run by Elsevier, and costs more than 15200 euros/year... so Vico was right, after all.) Nowadays, JHEP has become one of the major journals in the field: for instance, Ed Witten, Ashoke Sen and Cumrun Vafa regularly publish papers on JHEP. For what it is worth, in 2005 the JHEP Impact Factor was 5.944, that of Nuclear Physics B was 5.522. So on-line journals can compete with "standard" journals also on this point. As far as the "real existence" of online papers, especially for grant applications, career advancements, etc: if I remember correctly, from a formal point of view the only important thing is that to have an ISSN number - which means that the journal is officially recognized as a periodical publication. The existence of a "printed version" to store and forget in dusty (and increasingly deserted) libraries is not needed. -m -- Marino Miculan - http://www.dimi.uniud.it/miculan/ Department of Mathematics and Computer Science, University of Udine via delle Scienze 206, 33100 Udine - Italy -- skype: marinomiculan vox: +39-043255-8486 - fax: +39-043255-8499 - mob: +39-3292606452 From rrosebru@mta.ca Wed Jan 3 18:09:13 2007 -0400 Date: Wed, 03 Jan 2007 23:09:40 +0100 From: Andrej Bauer MIME-Version: 1.0 To: categories@mta.ca Subject: categories: Small semirings Content-Type: text/plain; charset=ISO-8859-2; format=flowed Content-Transfer-Encoding: 7bit Status: O X-Status: X-Keywords: X-UID: 57 Dear categorists, I have no idea where to ask the following algebra question. Hoping that some of you are algebraists, I am asking it here. I am looking for examples of small (finite and with few elements, say up to 8) commutative semirings with unit, by which I mean an algebraic structure which has +, *, 0 and 1, both operations are commutative and * distributes over +. The initial such structure are the natural numbers. Here are the examples I know: 1) Modular arithmetic, i.e., (Z_n, +, *, 0, 1) 2) Distributive lattices with 0 and 1. 3) "Cut-off" semiring, in which we compute like with natural numbers, but if a value exceeds a given constant N, then we cut it off at N. For example, if N = 7 then we would have 3 + 3 = 6, 3 + 6 = 7, 4 * 4 = 7, etc. Do such semirings have a name? There must be a census of small commutative rings, or even semirings. Does anyone know? Andrej From rrosebru@mta.ca Thu Jan 4 07:26:01 2007 -0400 Content-Type: text/plain; charset=US-ASCII; format=flowed To: categories@mta.ca From: Jon Cohen Subject: categories: USMC'07: Final call for talks and registration Date: Thu, 4 Jan 2007 22:25:48 +1100 Status: O X-Status: X-Keywords: X-UID: 58 FINAL CALL FOR TALKS AND REGISTRATION Universal Structures in Mathematics and Computing http://usmc07.rsise.anu.edu.au The Australian National University Canberra, Australia 5 - 7 February 2007 * Deadline for registration: 2nd February 2007 * Deadline for talk titles and abstracts submission: 19th January 2007 This workshop aims to bring together researchers working in category theory, universal algebra, logic and their applications to computer science in order to highlight recent advances in these fields and to facilitate dialogue between the different camps. Of particular interest is work which spans two or more of these areas. Keynote Speakers: * Brian Davey (La Trobe, Australia) * Rob Goldblatt (VUW, New Zealand) * Ross Street (Macquarie, Australia) * Glynn Winskel (Cambridge, UK) Please see the workshop website for futher details on registration, submission of talks, topics of interest and accommodation details. The workshop is sponsored by the Australian Mathematical Sciences Institute (AMSI) and National ICT Australia. From rrosebru@mta.ca Thu Jan 4 12:53:12 2007 -0400 Mime-Version: 1.0 (Apple Message framework v752.2) Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Content-Transfer-Encoding: 7bit From: Marco Grandis Subject: categories: re: Small semirings Date: Thu, 4 Jan 2007 17:52:53 +0100 To: categories@mta.ca Status: O X-Status: X-Keywords: X-UID: 59 This site lists a lot of algebraic structures and often gives information on finite examples: http://math.chapman.edu/cgi-bin/structures ----- Thus, for commutative rings (with 1) you have: http://math.chapman.edu/structuresold/files/ Commutative_rings_with_identity.pdf where you can find that there are: - 1 structure with 1 element (or 2, 3, 5, 6 elements) - 4 structures with 4 elements. ----- The case of semirings is not (yet?) much developed: just a few results and trivial examples. See: http://math.chapman.edu/structuresold/files/ Semirings_with_identity_and_zero.pdf http://math.chapman.edu/structuresold/files/Semirings_with_zero.pdf ------- Commutative semirings are not in the list, I think. Marco Grandis On 3 Jan 2007, at 23:09, Andrej Bauer wrote: > Dear categorists, > > I have no idea where to ask the following algebra question. Hoping > that > some of you are algebraists, I am asking it here. > > I am looking for examples of small (finite and with few elements, > say up > to 8) commutative semirings with unit, by which I mean an algebraic > structure which has +, *, 0 and 1, both operations are commutative > and * > distributes over +. The initial such structure are the natural > numbers. > > Here are the examples I know: > > 1) Modular arithmetic, i.e., (Z_n, +, *, 0, 1) > > 2) Distributive lattices with 0 and 1. > > 3) "Cut-off" semiring, in which we compute like with natural numbers, > but if a value exceeds a given constant N, then we cut it off at N. > For > example, if N = 7 then we would have 3 + 3 = 6, 3 + 6 = 7, 4 * 4 = 7, > etc. Do such semirings have a name? > > There must be a census of small commutative rings, or even semirings. > Does anyone know? > > Andrej > > > From rrosebru@mta.ca Thu Jan 4 17:26:46 2007 -0400 Date: Thu, 04 Jan 2007 13:26:36 -0800 From: Vaughan Pratt MIME-Version: 1.0 To: categories@mta.ca Subject: categories: Small semirings Content-Type: text/plain; charset=ISO-8859-2; format=flowed Content-Transfer-Encoding: 7bit Status: O X-Status: X-Keywords: X-UID: 60 Example (1) of section 3.2 of "Temporal Structures", MSCS 1:2 179-213 (1991), also at http://boole.stanford.edu/pub/man.pdf, enumerates the commutative semirings both of whose operations are idempotent (thus defining two partial orders), with the additive order furthermore being linear. We showed there are 2^{n-2} of these having n elements, and indicated where the first three (those with n = 2 or 3) have previously appeared in the literature. Interestingly the linearity of the additive order implies that of the multiplicative order. Once this has been shown it is an easy step to the following pleasant representation. Start with an n-element chain, n>1, viewed as a string of n beads with 0 at the bottom. Select any nonzero element as the (multiplicative) unit, and then determine the multiplication by allowing the portions of the string on either side of the unit to dangle down, with the beads interleaving arbitrarily subject to 0 remaining below the rest. One can then readily show that there are 2^{n-2} choices for the unit and multiplication. For each n exactly one of these is a Heyting algebra (example 2 of Andrej's list), namely the one for which the additive top was selected as the unit. (So for n = 2 or 3 only the one non-Heyting semiring will be at all unfamiliar.) I would be interested to hear of appearances in the literature of any of the three non-Heyting such with four elements. As a class exercise around 1989 I assigned the enumeration problem for various weakenings of these conditions, which I can't locate right now though Ken Ross, kar at cs columbia edu, might conceivably have kept a record. Vaughan Pratt Andrej Bauer wrote: > Dear categorists, > > I have no idea where to ask the following algebra question. Hoping that > some of you are algebraists, I am asking it here. > > I am looking for examples of small (finite and with few elements, say up > to 8) commutative semirings with unit, by which I mean an algebraic > structure which has +, *, 0 and 1, both operations are commutative and * > distributes over +. The initial such structure are the natural numbers. > > Here are the examples I know: > > 1) Modular arithmetic, i.e., (Z_n, +, *, 0, 1) > > 2) Distributive lattices with 0 and 1. > > 3) "Cut-off" semiring, in which we compute like with natural numbers, > but if a value exceeds a given constant N, then we cut it off at N. For > example, if N = 7 then we would have 3 + 3 = 6, 3 + 6 = 7, 4 * 4 = 7, > etc. Do such semirings have a name? > > There must be a census of small commutative rings, or even semirings. > Does anyone know? > > Andrej From rrosebru@mta.ca Thu Jan 4 19:59:16 2007 -0400 Date: Thu, 4 Jan 2007 19:59:14 -0400 (AST) From: Bob Rosebrugh To: categories Subject: categories: Call for volunteers Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Status: O X-Status: X-Keywords: X-UID: 61 Volunteers are sought to type part of an article from SLN#80, Seminar on Triples and Categorical Homology Theory in TeX. It is planned to republish these articles as a number in the TAC Reprints series. Diagrams will be handled separately. If a reasonable number of volunteers is available, it would be a fairly light piece of work for each of them. If interested, please contact me. Thanks, Bob Rosebrugh From rrosebru@mta.ca Fri Jan 5 13:06:44 2007 -0400 From: "Ronnie Brown" To: "categories" Subject: categories: Re: groupoids versus homotopy 1-types Date: Fri, 5 Jan 2007 17:06:06 -0000 MIME-Version: 1.0 Content-Type: text/plain;format=flowed; charset="iso-8859-1";reply-type=original Content-Transfer-Encoding: 7bit Status: O X-Status: X-Keywords: X-UID: 62 I don't have a specific reference in 2-category language but the following should be relevant: The notion of a homotopy theory for groupoids was set up in my 1968 topology book now revised and republished as Topology and Groupoids. In particular \pi_1: spaces \to groupoids preserves homotopies. Fibrations were introduced in an exercise, and developed in later editions. See also Philip Higgins' Categories and Groupoids, (1971) now available as a TAC reprint. The nerve and classifying space of a groupoid are in Graeme Segal's `Classifying spaces and spectral sequences' (IHES) utilising Grothendieck's nerve of a category. These preserve homotopy. The fact that for a CW-complex X, [X,BG] \cong [\pi_1 X, G] is also well known: P.Olum Ann Math 1958? There is also relevant material in Gabriel-Zisman's book, but I do not have it with me. People should also look at 2 papers on groupoids by P A Smith in the Annals, 1951. Hope that helps. Ronnie www.bangor.ac.uk/r.brown ----- Original Message ----- From: "John Baez" To: "categories" Sent: Wednesday, December 27, 2006 6:53 PM Subject: categories: groupoids versus homotopy 1-types > Dear Categorists - > > The following claim should be well-known (or false), > but I don't know a reference: > > Let Gpd be the 2-category consisting of > > groupoids > functors > natural transformations > > and let 1Type be the 2-category consisting of > > homotopy 1-types > continuous maps > homotopy classes of homotopies > > where for present purposes "homotopy 1-types" means "CW complexes with > vanishing higher homotopy groups regardless of the choice of basepoint". > > Claim: Gpd and 1Type are equivalent (or "biequivalent", > in older terminology). > > In fact I bet there is an explicit pseudo-adjunction between them, > with the "fundamental groupoid" 2-functor going one way and the > "Eilenberg-Mac Lane space" 2-functor going the other way. > > Does anyone know for sure? Know a reference? > > Best, > jb > > > > > > > > -- > Internal Virus Database is out-of-date. > Checked by AVG Free Edition. > Version: 7.1.409 / Virus Database: 268.15.6/565 - Release Date: 02/12/2006 > From rrosebru@mta.ca Thu Jan 4 20:25:51 2007 -0400 Date: Thu, 4 Jan 2007 19:25:44 -0500 (EST) From: Josh Nichols-Barrer To: categories@mta.ca Subject: categories: Re: Small semirings MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Status: O X-Status: X-Keywords: X-UID: 63 Hi Andrej, Here are some odds and ends: You can build a semiring from any semiring R with no nonzero additive inverses by attaching an element at infinity (\infty+x = \infty for all x and and \infty * x = \infty for nonzero x). Iterating this, you can have a hierarchy of elements at infinity, I suppose. For example, take your cutoff semiring and add an element at infinity; this gives some new specimens. More generally, you can use finitely generated semirings (over a given finite semiring, for example). The above construction would be the quotient of R[x] where every polynomial of degree greater than 0 is identified with x. For another example, any finite linearly ordered commutative monoid is naturally a semiring, where the addition is max and the multiplication is given by the monoid law. For example, "cutoff monoids" of N. This example is somehow lifted from tropical geometry, which is (speculatively) relative algebraic geometry over the semiring R\cup {-\infty}, where R here denotes the reals, the addition law is max and the multiplication is addition in R. Maybe a easier question is what are the "minimal" finite semirings, for some appropriate notion of minimal. I'm thinking something analogous to the notion of field for rings, although even to classify the finite fields takes a bit of clever work... Here is a different approach to the question (after a conversation with K. Kedlaya): Given a semiring R, you can "mod out by elements with additive inverses" by identifying a and b whenever there are x and y with a+x=b and b+y=a. This produces a new semiring R' where no element other than 0 has an additive inverse; the operation kills all rings and fixes distributive lattices and cutoff semirings. The resulting semiring has a natural ordering, namely a <= b iff there is an x with a+x = b (so that 0 is the least element). I don't know what to call these, maybe ordered semirings? As a next step, you can take an ordered semiring R as above and identify 1 with 2 to produce something even simpler. We still have a partial ordering, of course, and moreover addition is join: if b <= a and c <= a, then b+c <= a+a = a. This does nothing to distributive lattices or the ordered commutative monoids above, but it turns cutoff semirings into the semiring with elements {0,1} and 1+1=1. You might call these "tropical semirings." Finally, you might want to transform the multiplication in a tropical semiring R into meet. I guess this would be done by identifying everything greater than or equal to 1 with 1, and then identifying x^2 with x for each x. Summarizing, I guess, the forgetful functors BddDistLat --> TropSemiRing --> OrdSemiring --> Semiring all seem to have left adjoints. Maybe another way to look into semirings would be to study the fibres of the left adjoints? The adjunction between bounded distributive lattices and tropical semirings already looks interesting... Another thing that would be cool to see would be a duality theory for tropical semirings, maybe like the duality theory for bounded distributive lattices, as a way to get a handle on tropical semirings at least... Of course, what I'd really like to see is a geometric picture of Spec R for any semiring R, but that might take a little more work... Best, Josh On Wed, 3 Jan 2007, Andrej Bauer wrote: > Dear categorists, > > I have no idea where to ask the following algebra question. Hoping that > some of you are algebraists, I am asking it here. > > I am looking for examples of small (finite and with few elements, say up > to 8) commutative semirings with unit, by which I mean an algebraic > structure which has +, *, 0 and 1, both operations are commutative and * > distributes over +. The initial such structure are the natural numbers. > > Here are the examples I know: > > 1) Modular arithmetic, i.e., (Z_n, +, *, 0, 1) > > 2) Distributive lattices with 0 and 1. > > 3) "Cut-off" semiring, in which we compute like with natural numbers, > but if a value exceeds a given constant N, then we cut it off at N. For > example, if N = 7 then we would have 3 + 3 = 6, 3 + 6 = 7, 4 * 4 = 7, > etc. Do such semirings have a name? > > There must be a census of small commutative rings, or even semirings. > Does anyone know? > > Andrej > From rrosebru@mta.ca Wed Jan 10 08:16:21 2007 -0400 Mime-Version: 1.0 (Apple Message framework v752.2) Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Content-Transfer-Encoding: 7bit From: ICLP07 publicity Subject: categories: ICLP 2007: Call for Workshop Proposals Date: Wed, 10 Jan 2007 11:23:45 +0000 Status: RO X-Status: X-Keywords: X-UID: 64 (apologies for cross-posting) *** CALL FOR WORKSHOP PROPOSALS *** ICLP'07 23rd International Conference on Logic Programming September 8-13, 2007 Porto, Portugal URL: http://www.dcc.fc.up.pt/iclp07/ ICLP'07, the 23rd International Conference on Logic Programming, will be held in Porto (Portugal), from September 8 to 13, 2007. Workshops co-located with international conferences are perhaps the best place for the presentation of preliminary work or novel ideas, new open problems to a wide and interested audience. Co-located workshops also provide a venue for presenting specialized topics and opportunities for intensive discussions and project collaboration. The topics of the workshops co-located with ICLP'07 can cover any areas related to logic programming, (e.g., Theory, Implementation, Environments, Language Issues, Alternative Paradigms, Applications) including cross-disciplinary areas. However, any workshop proposal will be analyzed. The format of the workshop will be decided by the workshop organizer(s), but ample time must be allowed for general discussion. Workshops can vary in length, but the optimal duration will be half a day or a full day. Workshop Proposal: ================== Those intending to organize a workshop at ICLP'07 are invited to submit a workshop proposal. Proposals should be in English and about two pages in length. They should contain: * The title of the workshop. * A brief technical description of the topics covered by the workshop. * A discussion of the timeliness and relevance of the workshop. * A list of some related workshops held in the last years * The (preliminary) required number of half-days allotted to the workshop and an estimate of the number of expected attendees. * The names, affiliation and contact details (email, web page, phone, fax) of the workshop organizer(s) together with a designated contact person. * The previous experiences of the workshop organizing committee in workshop/conference organization. Proposals are expected in ASCII or PDF format. All proposals should be submitted to the Workshop Chair by email by February 14, 2007. Reviewing Process: ================== Each submitted proposal is reviewed by the Workshops Chair and the Conference Program Chairs. Proposals that appear well-organized and that fit the goals and scope of ICLP will be selected. The decision will be notified by email to the responsible organizer by February 28, 2007. The definitive length of the workshop will be planned according to the number of submissions received by the different workshops. For every accepted workshop, the ICLP local organizers will prepare a meeting place and can print the workshop proceedings, whose LaTeX preparation is however in charge to the workshop organizers. The workshop registration fees will be handled together with the conference fees. Workshop Organizers' Tasks: =========================== * Producing a "Call for Papers" for the workshop and posting it on the net and/or other means. Please provide a web page URL which can be linked into the ICLP'07 home page by April 15, 2007. * Providing a brief description of the workshop for the conference program. * Reviewing/accepting submitted papers. * Scheduling workshop activities in collaboration with the local organizers and the workshop chair. * Sending workshop program and workshop proceedings in pdf format to the workshop chair for printing (deadline to be defined) * The use of the Computing Research Repository (CoRR) for the workshop proceedings is strongly suggested (see http:// logicprogramming.org/ [Guidelines for electronic publishing of proceedings]) Location: ========= All workshops will take place in the city of Porto at the site of the main conference. See the ICLP'07 web site for location details. Important Dates: ================ February 14, 2007: Proposal submission deadline February 28, 2007: Acceptance notification April 15, 2007: Deadline for receipt of CFP and URL for workshop web page July 20, 2007: Deadline for preliminary proceedings September 8-13, 2007: ICLP'07 workshops Workshop Chair: =============== Agostino Dovier www.dimi.uniud.it/dovier ======================================================================== From rrosebru@mta.ca Wed Jan 10 13:34:39 2007 -0400 From: Matt Brin To: categories@mta.ca Subject: categories: A question about literature on operads and coherence Date: Wed, 10 Jan 2007 12:34:31 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Disposition: inline Status: O X-Status: X-Keywords: X-UID: 65 I am writing up material that has been taking shape over a number of years. The question is of the type "how much of this has been done before?" The shape of the math is that questions of coherence of categories with multiplication can be given a group theory flavor and so groups are injected in the middle of the discussion. I expect that little recognition will take place after the introduction of the groups, so my question focuses on what happens before the groups show up. I circulated this question a bit with the aid of a pdf file, but this list won't take attachments, so I will have to make do with some latex. The latex follows the signature. Any communication should be by direct email. I am far from a category theorist and do not follow this list. Thanks for any information, Matt Brin \documentclass[oneside]{amsart} \usepackage{amssymb} \usepackage[all]{xy} \DeclareMathAlphabet\EuScript{U}{eus}{m}{n} \newcommand{\scr}[1]{\EuScript{#1}} \begin{document} \newcommand{\ldoublet}{\xy(-4,-2); (0,2)**@{-}; (2,0)**@{-}; (-2,0); (0,-2)**@{-}; \endxy} \newcommand{\rdoublet}{\xy(4,-2); (0,2)**@{-}; (-2,0)**@{-}; (2,0); (0,-2)**@{-}; \endxy} If \(\scr{C}\) is a category with (functoral) mutliplication \(\otimes\), then inside the operad \(End_\scr{C}\) there is a suboperad \(\bigotimes\) derived from the multiplication \(\otimes\) and an obvious surjective map of operads \(h:\scr{T}\rightarrow \bigotimes\) whose domain is the operad of finite binary trees. This map will take, for example, the tree \(\rdoublet\) to the functor \begin{equation} \label {ExFunctA}(X,Y,Z)\mapsto X\otimes(Y\otimes Z)\end{equation} in \(End_{\scr{C}}\) and the tree \(\ldoublet\) to the functor \begin{equation} \label {ExFunctB} (X,Y,Z)\mapsto (X\otimes Y)\otimes Z \end{equation} in \(End_{\scr{C}}\). If there is a natural isomorphism \(\alpha\) given from the functor (\ref{ExFunctA}) to the functor (\ref{ExFunctB}) in \(End_{\scr{C}}\), then the isomorphisms generated in the usual way from (composites of expansions of instances of) \(\alpha\) and \(\alpha^{-1}\) and the identity isomorphisms on the functors in \(\bigotimes\) gives a category structure to \(\bigotimes\). There are now two category structures that we can put on the operad \(\scr{T}\) of finite binary trees. One is a ``pullback'' category structure that we get from the category structure on \(\bigotimes\) where we use \(h:\scr{T}\rightarrow \bigotimes\) to do the pullback. (Morphisms from \(T_1\) to \(T_2\) are just the morphisms from \(h(T_1)\) to \(h(T_2)\).) The other category structure on \(\scr{T}\) is the trivial structure in which every pair of trees with the same number of leaves gets a uniqe (iso)morphism between them in each direction. We let \(\bigotimes^h\) denote the pullback category and reuse the notation \(\scr{T}\) for the trivial category structure. There is a forgetful functor from \(\bigotimes^h\) to \(\scr{T}\) that is the identity on objects. The point of the coherence question is to ask whether this forgetful functor is an isomorphism. At this point we probably leave the realm that might seem familiar. However, I will press on in case the ``probably'' is wrong, and to tell what the point of all this is. Particularly pleasant properties of the operad \(\scr{T}\) allow one to compute two groups: one \(T(\bigotimes^h)\) from \(\bigotimes^h\) and another \(F\) from \(\scr{T}\). The second group is well known and is usually referred to as ``Thompson's group \(F\)'' so we have kept the letter \(F\) for it. There is a surjective homomorphism (call it a comparison homomorphism) \(\sigma\) from \(T(\bigotimes^h)\) to \(F\). The surjectivity is standard and the arguments are in MacLane paper noted below. Under the assumption that the multiplication \(\otimes\) has an identity (an object \(K\) in \(\scr{C}\) with a natural isomorphism \(\iota\) from the identity on \(\scr{C}\) to the functor \(X\mapsto X\otimes K\) with no further restrictions such as the satisfaction of a coherence property on the isomorphism \(\iota\)), then one proves easily that the associativity morphism \(\alpha\) makes the pentagonal diagrams commute if and only if the comparison homomorphism \(\sigma\) is an isomorphism. In fact, once a certain ``non-collapsing'' fact is proven from the existence of the identity \(K\), the rest is just a quote of definitions. Thus \(\scr{C}\) is a monoidal category if and only if the ``identity isomorphism'' \(\iota\) satisfies the usual coherence conditions on identities and the comparison homomorphism \(\sigma\) is an isomorphism. One can do exactly the same thing with symmetric, monoidal categories (in which case the comparison homomorphism is to a well known group known as Thompson's group \(V\)) and braided tensor categories (in which case the comparison homomorphism is to a group \(BV\) of mine that I call the braided version of \(V\)). In the case of symmetric, monoidal catetgories, the argument again boils down to a check of definitions once certain basic facts are established. In the case of braided tensor categories, there are real calculations that must be done since the definition of braided tensor categories reads very differently than it does for monoidal and symmetric, monoidal categories. This ends the summary. I can clarify my question a bit. I am familiar with the paper of MacLane in the Rice journal of 1963 on Natural associativity and commutativity. I am familiar with little else. This pretty much identifies the scope of my question. The language of operads does not appear in MacLane's paper and I am wondering how much of MacLane's results have been reworked to exploit operads and their structures. Referring to the summary above, I am curious about the structures that preceed the introduction of the group \(T(\bigotimes)\). \end{document} -- matt brin / math. dept / SUNY / Binghamton, NY 13902-6000 / (607)-777-2147 FAX: (607)-777-2450 EMAIL: matt@math.binghamton.edu WWW: http://math.binghamton.edu/matt From rrosebru@mta.ca Wed Jan 10 22:49:00 2007 -0400 Mime-Version: 1.0 (Apple Message framework v752.2) To: categories@mta.ca From: Jon Cohen Subject: categories: Re: A question about literature on operads and coherence Date: Thu, 11 Jan 2007 13:48:43 +1100 To: Matt Brin Content-Transfer-Encoding: 7bit Content-Type: text/plain;charset=US-ASCII;delsp=yes;format=flowed Status: O X-Status: X-Keywords: X-UID: 66 Hello, On 11/01/2007, at 4:34 AM, Matt Brin wrote: > I am writing up material that has been taking shape over a number of > years. The question is of the type "how much of this has been done > before?" > > The shape of the math is that questions of coherence of categories > with > multiplication can be given a group theory flavor and so groups are > injected in the middle of the discussion. Patrick Dehornoy has some results on relating Thompson's groups to coherence in monoidal categories and the like. The papers that spring to mind are: The structure group for the associativity identity; J. P. Appl. Algebra 111 (1996) 59-82; Geometric presentations for Thompson's groups; Journal of Pure and Applied Algebra, 203 (2005) 1-44 Both of these can be found on his webpage at http:// www.math.unicaen.fr/~dehornoy/papers.html Best regards, Jon -- http://rsise.anu.edu.au/~jon From rrosebru@mta.ca Thu Jan 11 06:53:00 2007 -0400 From: Thomas Streicher Subject: categories: Workshop announcement (Domains VIII) To: categories@mta.ca Date: Thu, 11 Jan 2007 11:52:44 +0100 (CET) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII Status: O X-Status: X-Keywords: X-UID: 67 This announcement is also attached as a pdf-file Announcement and Call for Abstracts Joint Workshop Domains VIII and Computability Over Continuous Data Types Novosibirsk, September 11 -- 15, 2007 The Workshop 'Domains' series is aimed at computer scientists and mathematicians alike who share an interest in the mathematical foundations of computation. It focusses on domain theory, its applications and related topics. It will be combined with topics based on the German--Russian project 'Computability Over Non-discrete Structures: Models, Semantics, Complexity' supported by Russian Foundation for Basic Research (RFBR) and Deutsche Forschungsgemeinschaft (DFG). Webpage: www.sbras.ru/ws/domains/ (Switch to English - upper right corner) email: domains@math.nsc.ru SCOPE Topics for this workshop include, but are not limited to domains and topology for semantics effective domains and spaces computation over continuous spaces program semantics models of sequential computation lambda calculus realizability proof mining constructive mathematics and its semantics computability theory computable models admissible sets LOCATION The Workshop will take place at the Sobolev Instituts of Mathematics of the Siberian Branch of the Russian Academy of Sciences located in Akademgorodok, which is formally a district of Novosibirsk. PARTICIPATION If you would like to participate in this workshop, please let us know your interest at an early stage. Please indicate whether you intend to give a talk: domains@math.nsc.ru SUBMISSION OF ABSTRACTS One page abstracts should be submitted to domains@math.nsc.ru Shortly after an abstract is submitted (usually a few weeks), the authors will be notified by the programme committee. Abstracts will be dealt with on a first come/first served basis. Submit as soon as possible. DEADLINE 15 May 2007\\[2mm] INVITED SPEAKERS will be announced later on. PROCEEDINGS Conference Proceedings will be published in a Journal. Submission for the Proceddings will be after the Workshop. They will be refereed according to the usual requirements of the Journal. ACCOMODATION All participants will be accommodated in the Hotel ``Zolotaya Dolina'' (Gold Valley) situated at walking distance from the Instituts of Mathematics. FEES There will be a registration fee of 85 Euros for covering expenses. For participants from Eastern Europa and the former Soviet Union we set the fee 300 Russian Roubles. PhD students do not pay a fee. If the fee is a problem, please contact the organizers for a possible arrangement in advance. VISAS AND REGISTRATION Most foreign participants will need a visa to enter Russia. We will inform you later about details. You also can find details at http://www.ict.nsc.ru/ws/ALC-9/visa.htm For obtaining a visa, one needs an official invitation issued by the local authorities at Novosibirsk. The processing of invitations takes about one month; in addition, please allow some time for sending it by mail!} DEADLINE for registration: 30 June, 2007 PROGRAMME COMMITTEE Yuri Ershov Sobolev Institute of Mathematics, Novosibirsk Sergei Goncharov Sobolev Institute of Mathematics, Novosibirsk Achim Jung University of Birmingham, Birmingham Klaus Keimel (Chair) Darmstadt Technical University, Darmstadt Ulrich Kohlenbach Darmstadt Technical University, Darmstadt Andrei Morozov (Co-Chair) Sobolev Institute of Mathematics, Novosibirsk Victor Selivanov Novosibirsk State Pedagogical University, Novosibirsk Dieter Spreen University of Siegen, Siegen WORKSHOP SECRETARY Alexei Stukachev (domains@math.nsc.ru) From rrosebru@mta.ca Tue Jan 16 10:17:26 2007 -0400 From: Gaucher Philippe To: categories@mta.ca Subject: categories: Grothendieck construction Date: Tue, 16 Jan 2007 15:17:02 +0100 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Disposition: inline Status: O X-Status: X-Keywords: X-UID: 68 Dear All, Where does the Grothendieck construction come from ? What is the original reference ? Here is the construction. Take a functor H:I-->Cat (the category of small categories) The objects are the pairs (i,a) where a is an object of H(i). A morphism (i,a)-->(j,b) consists of a morphism f:i-->j of I and a morphism H(f)(a)-->b of H(j). pg. From rrosebru@mta.ca Tue Jan 16 05:16:39 2007 -0400 From: Andrei Sabelfeld To: categories@mta.ca Subject: categories: IEEE Computer Security Foundations Symposium 2007 - CFP Content-Type: text Date: Tue, 16 Jan 2007 10:16:22 +0100 (MET) Status: O X-Status: X-Keywords: X-UID: 69 [New: CSF is now an IEEE symposium.] Call For Papers 20th IEEE Computer Security Foundations Symposium (CSF) Venice, Italy, July 6 - 8, 2007 Sponsored by the Technical Committee on Security and Privacy of the IEEE Computer Society CSF20 website: http://www.dsi.unive.it/CSF20/ CSF home page: http://www.ieee-security.org/CSFWweb/ CSF CFP: http://www.cs.chalmers.se/~andrei/CSF07/cfp.html The IEEE Computer Security Foundations (CSF) series brings together researchers in computer science to examine foundational issues in computer security. Over the past two decades, many seminal papers and techniques have been presented first at CSF. The CiteSeer Impact page (http://citeseer.ist.psu.edu/impact.html ) lists CSF as 38th out of more than 1200 computer science venues in impact (top 3.11%) based on citation frequency. Notice: This event was previously known as IEEE Computer Security Foundations Workshop (CSFW). We are proud to announce that it has been upgraded to IEEE Symposium starting from this 20th edition. New theoretical results in computer security are welcome. Also welcome are more exploratory presentations, which may examine open questions and raise fundamental concerns about existing theories. Panel proposals are welcome as well as papers. Possible topics include, but are not limited to: Authentication Access control Distributed systems Information flow Trust and trust security Security management Security for mobile protocols Security models computing Anonymity and Intrusion Executable content Privacy detection Decidability and Electronic voting Data and system complexity Network security integrity Formal methods for Resource usage Database security security control Language-based security Proceedings published by the IEEE Computer Society Press will be available at the symposium, and selected papers will be invited for submission to the Journal of Computer Security. Important Dates Papers due: Monday, February 5, 2007 Panel proposals due: Thursday, March 15, 2007 Notification: Monday, March 26, 2007 Camera-ready papers: Friday, April 27, 2007 Symposium: July 6-8, 2007 Program Committee Tuomas Aura, Microsoft Research, UK Michael Backes, Saarland University, Germany Bruno Blanchet, ENS, France Iliano Cervesato, Carnegie Mellon University, Qatar George Danezis, K.U.Leuven, Belgium Herve Debar, France Telecom, France Riccardo Focardi, University of Venice, Italy Dieter Gollmann, Hamburg University of Technology, Germany Carl A. Gunter, University of Illinois at Urbana-Champaign, USA Joshua Guttman, MITRE, USA Masami Hagiya, University of Tokyo, Japan Jonathan Herzog, Naval Postgraduate School, USA Ninghui Li, Purdue University, USA Cathy Meadows, NRL, USA Jonathan Millen, MITRE, USA John Mitchell, Stanford University, USA Flemming Nielson, Technical University of Denmark, Denmark Riccardo Pucella, Northeastern University, USA Andrei Sabelfeld, Chalmers University of Technology, Sweden (chair) Pierangela Samarati, University of Milan, Italy Ravi Sandhu, George Mason University and TriCipher, USA Andre Scedrov, University of Pennsylvania, USA Vitaly Shmatikov, University of Texas at Austin, USA Geoffrey Smith, Florida International University, USA Steve Zdancewic, University of Pennsylvania, USA Symposium Location The 20th IEEE Computer Security Foundations Symposium will be held in the facilities of Venice International University, located on the island of San Servolo, about 10 minutes by water ferry from the Piazza San Marco. Instructions for Participants Although submission is open to anyone, attendance is by invitation. All authors of accepted papers are invited to attend, and authors are required to ensure that at least one will be present. This year's meeting location will allow us to invite more participants than previous years. Submission Instructions Submitted papers must not substantially overlap with papers that have been published or that are simultaneously submitted to a journal or a conference with published proceedings. Papers should be submitted in Postscript or Portable Document Format (PDF). Papers submitted in a proprietary word processor format such as Microsoft Word cannot be considered. At least one coauthor of each accepted paper is required to attend CSF to present the paper. Papers may be submitted using the two-column IEEE Proceedings style available for various document preparation systems at IEEE-CS Press. Papers in this style should be at most 12 pages long, not counting bibliography and well-marked appendices. Alternatively, papers can be in Springer LLNCS style. In LLNCS style papers must be at most 20 pages long excluding the bibliography and well-marked appendices. Committee members are not required to read appendices, and so the paper must be intelligible without them. Papers not adhering to the page limits will be rejected without consideration of their merits. The paper submission website will be open in January 2007. Proposals for panels are also welcome. They should be no more than five pages in length and should include possible panelists and an indication of which of those panelists have confirmed a desire to participate. They should be submitted by email to the program chair by March 15, 2007. A session of five-minute talks was successful in the last two years, so we are likely to have one again in 2007. Abstracts will be solicited in May. There are PDF and HTML versions of this call for papers at http://www.cs.chalmers.se/~andrei/CSF07/cfp.html . For further information contact: +-----------------------------------------------------------------+ |General Chair |Program Chair |Publications | | | |Chair | |-----------------------+------------------ +-------------------| |Riccardo Focardi |Andrei Sabelfeld |Jonathan Herzog | |Universita di |Chalmers |Computer Science | |Venezia, Informatica |University of |Naval Postgraduate | |Via Torino 155 |Technology |School | |I-30172 Mestre (Ve), |41296 Gothenburg, |Monterey CA, 93943 | |Italy |Sweden |USA | |+39 041 2348 438 |+46 31 772 1000 |+1 831 656 3990 | |focardi AT dsi.unive.it|andrei AT chalmers.se|jcherzog AT nps.edu| +-----------------------------------------------------------------+ From rrosebru@mta.ca Tue Jan 16 21:23:57 2007 -0400 To: Gaucher Philippe Subject: categories: Re: Grothendieck construction Date: Tue, 16 Jan 2007 20:23:44 -0500 From: wlawvere@buffalo.edu MIME-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 8bit Status: O X-Status: X-Keywords: X-UID: 70 Because Grothendieck made many constructions that became iconic, the terminology is ambiguous. I call this construction "the Grothendieck semi-direct product" because the formula for composition of these morphisms is exactly the same as in the very special case where I is a group. Of course the result of the construction is a single category "fibered" over I and every fibred category so arises. The original example for me (1959) was that from Cartan-Eilenberg where I is a category of rings and H(i) is the category of modules over i. Because J. L. Kelley had proposed "galactic" as the analogue at the Cat level of the traditional "local" at the level of a space, I called such an H a "galactic cluster" . The "fibration' terminology and the accompanying results and definitions for descent etc were presented by AG in Paris seminars in the very early 1960's and can probably be accessed elecronically now. Best wishes Bill Quoting Gaucher Philippe : > Dear All, > > Where does the Grothendieck construction come from? What is the > original > reference? Here is the construction. > > Take a functor H:I-->Cat (the category of small categories) > > The objects are the pairs (i,a) where a is an object of H(i). > A morphism (i,a)-->(j,b) consists of a morphism f:i-->j of I and a > morphism > H(f)(a)-->b of H(j). > > pg. > From rrosebru@mta.ca Wed Jan 17 04:47:12 2007 -0400 Date: Wed, 17 Jan 2007 09:47:01 +0100 (CET) Subject: categories: Re: Grothendieck construction From: "Artur Zawlocki" To: categories@mta.ca MIME-Version: 1.0 Content-Type: text/plain;charset=iso-8859-2 Content-Transfer-Encoding: quoted-printable Status: O X-Status: X-Keywords: X-UID: 71 > Dear All, > > Where does the Grothendieck construction come from? What is the origina= l > reference? Here is the construction. A standard reference is (after Wikipedia, http://en.wikipedia.org/wiki/Grothendieck's_S%C3%A9minaire_de_g%C3%A9om%C= 3%A9trie_alg%C3%A9brique): Grothendieck, Alexandre, S=E9minaire de G=E9om=E9trie Alg=E9brique du Boi= s Marie - 1960-61 - Revêtements =E9tales et groupe fondamental - (SGA 1) (Lect= ure notes in mathematics 224) (in French). Berlin; New York: Springer-Verlag, xxii+447. ISBN 3540056149. An updated version has been put in the arxiv: http://www.arxiv.org/abs/math.AG/0206203 The construction itself is defined in Section 8, as far as I remember. Artur > > Take a functor H:I-->Cat (the category of small categories) > > The objects are the pairs (i,a) where a is an object of H(i). > A morphism (i,a)-->(j,b) consists of a morphism f:i-->j of I and a > morphism > H(f)(a)-->b of H(j). > > pg. > > > From rrosebru@mta.ca Thu Jan 18 12:03:19 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Thu, 18 Jan 2007 12:03:19 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1H7ZcH-0004ud-Uu for categories-list@mta.ca; Thu, 18 Jan 2007 11:55:54 -0400 Date: Thu, 18 Jan 2007 01:18:17 -0500 (EST) From: Phil Scott To: categories@mta.ca Subject: categories: Second Announcement of Fields Workshop on Traced Monoidal Cats Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: cat-dist@mta.ca Precedence: bulk Status: RO X-Status: X-Keywords: X-UID: 72 Dear Colleagues: We would like to announce the following: ============================================================== A Fields Institute Sponsored Workshop Recent advances in category theory and logic: Applications of traces to algebra, analysis and categorical logic University of Ottawa April 28-30, 2007 URL: http://aix1.uottawa.ca/~scpsg/Fields07/Fields07.traces.html +++++++++++++++++++++++++++++++++++++++++++++++ The abstract theory of traces has had a fundamental impact on a variety of fields within mathematics. These range from functional analysis and noncommutative geometry to topology and knot theory, and more recently to logic and theoretical computer science. The theory of traced monoidal categories, due to Joyal, Street and Verity, is an attempt to unify various notions of trace that occur in these diverse branches of mathematics. More recent developments include several theories of partial traces in monoidal categories. The Logic and Foundations of Computing Group at the University of Ottawa, with funding from the Fields Institute, is proud to host a workshop to explore these topics. The purpose of this workshop is to bring together researchers in these fields to look for common developments, models, and applications of trace theory. Among the applications are various notions of parametrized traces arising in operator algebras, in the theory of feedback and recursion in theoretical computer science, in braid closure in knot theory, and in dynamics of proofs as expressed by Linear Logic and the Geometry of Interaction. Some invited speakers include: Samson Abramsky (Oxford) Robin Cockett (Calgary) Andre Joyal (UQAM) Louis Kauffman (Illinois) Mathias Neufang (Carleton) Timothy Porter (Bangor) We will be announcing further speakers shortly. This is intended to be a workshop, with student participation in mind, including introductory lectures. We will have some funding for student travel and accommodation. Students interested in receiving financial aid should contact the organizers by January 30th. Anyone interested in attending or contributing a talk should contact us by the same date. We hope to see you there. The organizers: Phil Scott (phil@site.uottawa.ca) Rick Blute (rblute@uottawa.ca) Pieter Hofstra (hofstrap@cpsc.ucalgary.ca) From rrosebru@mta.ca Thu Jan 18 12:03:19 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Thu, 18 Jan 2007 12:03:19 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1H7ZbA-0004lg-NG for categories-list@mta.ca; Thu, 18 Jan 2007 11:54:44 -0400 From: "Dr. Keith G. Bowden" To: Subject: categories: Re: semi direct product Date: Wed, 17 Jan 2007 13:52:12 -0000 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: O X-Status: X-Keywords: X-UID: 73 Dear Bill, Your reply is slightly ambiguous. Do you mean that you call it the semidirect product by extension of the semi-direct product in group theory? Regards, Keith Bowden ----- Original Message ----- From: To: Sent: Wednesday, January 17, 2007 1:23 AM > Because Grothendieck made many constructions that > became iconic, the terminology is ambiguous. > I call this construction > "the Grothendieck semi-direct product" > because the formula for composition of these > morphisms is exactly the same as in the very special > case where I is a group. > Of course the result of the construction is a single > category "fibered" over I and every fibred category > so arises. > The original example for me (1959) was that from > Cartan-Eilenberg where I is a category of rings and > H(i) is the category of modules over i. Because > J. L. Kelley had proposed "galactic" as the analogue > at the Cat level of the traditional "local" at the level > of a space, I called such an H a "galactic cluster" . > The "fibration' terminology and the accompanying > results and definitions for descent etc were presented > by AG in Paris seminars in the very early 1960's and > can probably be accessed elecronically now. > > Best wishes > Bill > > Quoting Gaucher Philippe : > > > Dear All, > > > > Where does the Grothendieck construction come from? What is the > > original > > reference? Here is the construction. > > > > Take a functor H:I-->Cat (the category of small categories) > > > > The objects are the pairs (i,a) where a is an object of H(i). > > A morphism (i,a)-->(j,b) consists of a morphism f:i-->j of I and a > > morphism > > H(f)(a)-->b of H(j). > > > > pg. > > > > > > > > > > From rrosebru@mta.ca Fri Jan 19 08:58:34 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Fri, 19 Jan 2007 08:58:34 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1H7tH8-0006v0-Vc for categories-list@mta.ca; Fri, 19 Jan 2007 08:55:23 -0400 Date: Thu, 18 Jan 2007 22:36:25 -0800 From: Toby Bartels To: categories@mta.ca Subject: categories: Exactness without pullbacks Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: O X-Status: X-Keywords: X-UID: 74 Has anybody considered (and are there any references with standard results) categories that do *not* have *all* pullbacks but nevertheless have some nice exactness properties? For example, instead of saying that regular epis are stable under pullback (so that the pullback of a regular epi along any map is also regular-epic), I might say that any pullback of a regular epi is regular-epic *if* it exists. (I might instead use a weaker variant, requiring this only in the case that *all* pullbacks of the regular epi in question exist; or else requiring that all pullbacks of *all* regular epis exist, yielding a stronger variant). For a more specific example, the category of smooth manifolds misses many pullbacks but has the property above (at least the weaker form; as I recall, the surjective submersions are precisely those regular epis that have all pullbacks, but I forget if any other regular epis exist; in any case, the pullback of a surjective submersion along any smooth map exists and is also surjective-submersive). --Toby From rrosebru@mta.ca Fri Jan 19 08:58:34 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Fri, 19 Jan 2007 08:58:34 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1H7tEv-0006iE-TN for categories-list@mta.ca; Fri, 19 Jan 2007 08:53:05 -0400 Date: Thu, 18 Jan 2007 20:50:54 +0100 (CET) From: "I. Moerdijk" Subject: categories: Grothendieck construction To: categories@mta.ca MIME-Version: 1.0 Content-Type: TEXT/plain; charset=us-ascii Content-MD5: HvidpKxkHXrqff3qImiKew== Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: O X-Status: X-Keywords: X-UID: 75 Perhaps I should add that Saunders Mac Lane was always a bit unhappy with this terminology, and has told me repeatedly that "he knew it long before Grothendieck...". Ieke Moerdijk. From rrosebru@mta.ca Fri Jan 19 08:58:34 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Fri, 19 Jan 2007 08:58:34 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1H7tGK-0006qi-KZ for categories-list@mta.ca; Fri, 19 Jan 2007 08:54:32 -0400 Date: Fri, 19 Jan 2007 09:50:02 +0100 From: metere@mat.unimi.it To: categories@mta.ca Subject: categories: Re: semi direct product MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: O X-Status: X-Keywords: X-UID: 76 Dear Keith, This reply to the reply is actually more ambiguous... What do you mean with "extension"? Anyway, I find it interesting, in the groupoids case, the paper: "Categorical non abelian cohomology, and the Schreier theory of groupoids", V. Blanco, M. Bullejos, E. Faro, on the arXiv as math.CT/0410202. Best regards, Beppe Metere. Quoting "Dr. Keith G. Bowden" : > Dear Bill, > > Your reply is slightly ambiguous. > > Do you mean that you call it the semidirect product by extension of the > semi-direct product in group theory? > > Regards, > Keith Bowden > > > ----- Original Message ----- > From: > To: > Sent: Wednesday, January 17, 2007 1:23 AM > > > > Because Grothendieck made many constructions that > > became iconic, the terminology is ambiguous. > > I call this construction > > "the Grothendieck semi-direct product" > > because the formula for composition of these > > morphisms is exactly the same as in the very special > > case where I is a group. > > Of course the result of the construction is a single > > category "fibered" over I and every fibred category > > so arises. > > The original example for me (1959) was that from > > Cartan-Eilenberg where I is a category of rings and > > H(i) is the category of modules over i. Because > > J. L. Kelley had proposed "galactic" as the analogue > > at the Cat level of the traditional "local" at the level > > of a space, I called such an H a "galactic cluster" . > > The "fibration' terminology and the accompanying > > results and definitions for descent etc were presented > > by AG in Paris seminars in the very early 1960's and > > can probably be accessed elecronically now. > > > > Best wishes > > Bill > > > > Quoting Gaucher Philippe : > > > > > Dear All, > > > > > > Where does the Grothendieck construction come from? What is the > > > original > > > reference? Here is the construction. > > > > > > Take a functor H:I-->Cat (the category of small categories) > > > > > > The objects are the pairs (i,a) where a is an object of H(i). > > > A morphism (i,a)-->(j,b) consists of a morphism f:i-->j of I and a > > > morphism > > > H(f)(a)-->b of H(j). > > > > > > pg. > > > > > > > > > > > > > > > > > > > Quoting "Dr. Keith G. Bowden" : > Dear Bill, > > Your reply is slightly ambiguous. > > Do you mean that you call it the semidirect product by extension of the > semi-direct product in group theory? > > Regards, > Keith Bowden > > > ----- Original Message ----- > From: > To: > Sent: Wednesday, January 17, 2007 1:23 AM > > > > Because Grothendieck made many constructions that > > became iconic, the terminology is ambiguous. > > I call this construction > > "the Grothendieck semi-direct product" > > because the formula for composition of these > > morphisms is exactly the same as in the very special > > case where I is a group. > > Of course the result of the construction is a single > > category "fibered" over I and every fibred category > > so arises. > > The original example for me (1959) was that from > > Cartan-Eilenberg where I is a category of rings and > > H(i) is the category of modules over i. Because > > J. L. Kelley had proposed "galactic" as the analogue > > at the Cat level of the traditional "local" at the level > > of a space, I called such an H a "galactic cluster" . > > The "fibration' terminology and the accompanying > > results and definitions for descent etc were presented > > by AG in Paris seminars in the very early 1960's and > > can probably be accessed elecronically now. > > > > Best wishes > > Bill > > > > Quoting Gaucher Philippe : > > > > > Dear All, > > > > > > Where does the Grothendieck construction come from? What is the > > > original > > > reference? Here is the construction. > > > > > > Take a functor H:I-->Cat (the category of small categories) > > > > > > The objects are the pairs (i,a) where a is an object of H(i). > > > A morphism (i,a)-->(j,b) consists of a morphism f:i-->j of I and a > > > morphism > > > H(f)(a)-->b of H(j). > > > > > > pg. > > > > > > > > > > > > > > > > > > > ---------------------------------------------------------------- From rrosebru@mta.ca Fri Jan 19 19:42:59 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Fri, 19 Jan 2007 19:42:59 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1H83Gk-0002Cx-9K for categories-list@mta.ca; Fri, 19 Jan 2007 19:35:38 -0400 Subject: categories: Re: Exactness without pullbacks From: Eduardo Dubuc Date: Fri, 19 Jan 2007 15:35:22 -0300 (ART) To: categories@mta.ca MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: O X-Status: X-Keywords: X-UID: 77 > > Has anybody considered (and are there any references with standard results) > categories that do *not* have *all* pullbacks > but nevertheless have some nice exactness properties? > > For example, instead of saying that regular epis are stable under pullback > (so that the pullback of a regular epi along any map is also regular-epic), grothendieck notion of strict epi (SGA4) is equivalent to the notion of regular epi in the presence of the kernel-pair, but it makes sense in the absence of pull-backs. you can say that a strict epi is "stable under pullbacks" also in the absence of pullbacks: Z_i -------> X | | |f_i |f \/ h \/ Z --------> Y a strict epi f is universal if given any h there exists a strict epi family f_i as indicated in the diagram. this exactness property is as good as stability under pullbacks see the links http://arXiv.org/abs/math/0611701 http://arXiv.org/abs/math/0612727 i am afraid thought that you have different examples in mind. eduardo j. dubuc From rrosebru@mta.ca Fri Jan 19 19:42:59 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Fri, 19 Jan 2007 19:42:59 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1H83Hw-0002I0-3S for categories-list@mta.ca; Fri, 19 Jan 2007 19:36:52 -0400 From: "David Espinosa" To: Subject: categories: Re: Grothendieck construction Date: Fri, 19 Jan 2007 10:44:48 -0800 MIME-Version: 1.0 Content-Type: text/plain;format=flowed;charset="iso-8859-1";reply-type=original Content-Transfer-Encoding: 7bit Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: O X-Status: X-Keywords: X-UID: 78 > "he knew it long before Grothendieck..." So maybe the construction itself is obvious, particularly if you know the semi-direct product or some other specialization (of the general construction). But the intrinic characterization of what the construction yields, that is, the definition of a fibration, seems less obvious. I'm sure everyone has a favorite example of that. For example, Carsten Fuhrmann gave an intrinsic description of the Kleisli category of a monad only in 1999. His home page is: http://www.cs.bath.ac.uk/~cf/ David From rrosebru@mta.ca Fri Jan 19 19:42:59 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Fri, 19 Jan 2007 19:42:59 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1H83KX-0002QL-Qd for categories-list@mta.ca; Fri, 19 Jan 2007 19:39:33 -0400 Date: Fri, 19 Jan 2007 14:26:05 -0500 (EST) From: F W Lawvere To: categories@mta.ca Subject: categories: Re: semi direct product MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: O X-Status: X-Keywords: X-UID: 79 Dear colleagues, The terminology "Grothendieck semi-direct product" is just to reduce terminological ambiguity. For example, if a colloquium talk is advertised by a title that includes the term "Grothendieck construction", should we expect that it will involve the process of passing from a galactic cluster to the associated fibration? No, not necessarily, because that term is also routinely applied in other ways, for example to his construction in K-theory. That Grothendieck construction within K-theory is also tautological (the reflection of rigs into commutative rings), but Grothendieck realized that it could have profound content: unlike the cases taught in junior high school, the adjunction map can degrade information, with the useful result that the ring becomes more calculable, while still determining the rank of a module at each point of a parameter space; the successes of his approach led to further dissemination of the philosophy that for measuring the objects in some category, the rigs that are appropriate depend on the category. The principle that seemingly simple constructions can have profound content was demonstrated many times by Grothendieck, not only by the idea of K-theory, but by the fibered category concept of the present discussion. The universal semi-direct product formula, (defining the composition of pairs of the kind ) was long known in group theory. That it describes the total category of a galactic cluster may well have been known to some before 1960, but the realization and popularization of new geometrical applications justify attaching Grothendieck's name to this kind of semi-direct product. Certain fibered categories, under names like "covariance system", are a key ingredient giving operator theory a content that transcends the study of linear operators as such. For example, on a base category of smooth spaces we can consider for each X the category (with one object) A(X) of smooth functions under multiplication. Then in the total category one can recognize the "Canonical Commutation Relations" between q in a fiber and m in the base (special operators p arise as limits of difference quotients of families of such m). Despite the continuing restrictive influence of Klein's "Erlanger Programm", one can note that m need NOT be invertible; paths, inclusion maps, projections, etc. are typically maps m in the base that can also operate on the q's. In this sense, the fibered category is an extension of the group case. Bill Lawvere On Wed, 17 Jan 2007, Dr. Keith G. Bowden wrote: > Dear Bill, > > Your reply is slightly ambiguous. > > Do you mean that you call it the semidirect product by extension of the > semi-direct product in group theory? > > Regards, > Keith Bowden > > > ----- Original Message ----- > From: > To: > Sent: Wednesday, January 17, 2007 1:23 AM > > > > Because Grothendieck made many constructions that > > became iconic, the terminology is ambiguous. > > I call this construction > > "the Grothendieck semi-direct product" > > because the formula for composition of these > > morphisms is exactly the same as in the very special > > case where I is a group. > > Of course the result of the construction is a single > > category "fibered" over I and every fibred category > > so arises. > > The original example for me (1959) was that from > > Cartan-Eilenberg where I is a category of rings and > > H(i) is the category of modules over i. Because > > J. L. Kelley had proposed "galactic" as the analogue > > at the Cat level of the traditional "local" at the level > > of a space, I called such an H a "galactic cluster" . > > The "fibration' terminology and the accompanying > > results and definitions for descent etc were presented > > by AG in Paris seminars in the very early 1960's and > > can probably be accessed elecronically now. > > > > Best wishes > > Bill > > > > Quoting Gaucher Philippe : > > > > > Dear All, > > > > > > Where does the Grothendieck construction come from? What is the > > > original > > > reference? Here is the construction. > > > > > > Take a functor H:I-->Cat (the category of small categories) > > > > > > The objects are the pairs (i,a) where a is an object of H(i). > > > A morphism (i,a)-->(j,b) consists of a morphism f:i-->j of I and a > > > morphism > > > H(f)(a)-->b of H(j).> > > > > > pg. > > > > > > > > > > > > > > > > > > > > > From rrosebru@mta.ca Fri Jan 19 19:42:59 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Fri, 19 Jan 2007 19:42:59 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1H83FI-00026G-Dc for categories-list@mta.ca; Fri, 19 Jan 2007 19:34:08 -0400 Date: Fri, 19 Jan 2007 08:33:20 -0800 From: Toby Bartels To: categories@mta.ca Subject: categories: Re: Exactness without pullbacks Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: O X-Status: X-Keywords: X-UID: 80 Michael Barr wrote: >Toby Bartels wrote: >>Has anybody considered (and are there any references with standard results) >>categories that do *not* have *all* pullbacks >>but nevertheless have some nice exactness properties? >My recollection is that in the original definition only pullbacks of >regular epis as well as kernel pairs were assumed to exist. By "the original definition", you mean the definitions here?: Michael Barr, Exact categories, in Exact Categories and Categories of Sheaves, Lecture Notes in Mathematics 236, Springer-Verlag, 1971. I've never read this, since you-exact categories are now standard, but I guess that one should always go back to the source! --Toby From rrosebru@mta.ca Fri Jan 19 19:42:59 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Fri, 19 Jan 2007 19:42:59 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1H83EU-00022s-3J for categories-list@mta.ca; Fri, 19 Jan 2007 19:33:18 -0400 Date: Fri, 19 Jan 2007 09:23:32 -0500 (EST) From: Michael Barr To: categories@mta.ca Subject: categories: Re: Exactness without pullbacks MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: O X-Status: X-Keywords: X-UID: 81 My recollection is that in the original definition only pullbacks of regular epis as well as kernel pairs were assumed to exist. Although you could just assume that when the pullback of a regular epi exists it is a regular epic, I think that would vitiate the definition. However, one possibility that I have known of for a long time but not written about is to suppose that when A --> B is regular epic and B' --> B is arbitrary and you look at all pairs A' --> A, A' --> B' that make the evident square commute, then the family of all those A' --> B' is an effective epic family. In that category, a pullback, if it exists, is terminal. On Thu, 18 Jan 2007, Toby Bartels wrote: > Has anybody considered (and are there any references with standard results) > categories that do *not* have *all* pullbacks > but nevertheless have some nice exactness properties? > > For example, instead of saying that regular epis are stable under pullback > (so that the pullback of a regular epi along any map is also regular-epic), > I might say that any pullback of a regular epi is regular-epic *if* it exists. > (I might instead use a weaker variant, requiring this only in the case > that *all* pullbacks of the regular epi in question exist; > or else requiring that all pullbacks of *all* regular epis exist, > yielding a stronger variant). > > For a more specific example, the category of smooth manifolds > misses many pullbacks but has the property above (at least the weaker form; > as I recall, the surjective submersions are precisely those regular epis > that have all pullbacks, but I forget if any other regular epis exist; > in any case, the pullback of a surjective submersion along any smooth map > exists and is also surjective-submersive). > > > --Toby > > From rrosebru@mta.ca Fri Jan 19 19:42:59 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Fri, 19 Jan 2007 19:42:59 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1H83Fl-00028T-7b for categories-list@mta.ca; Fri, 19 Jan 2007 19:34:37 -0400 Date: Fri, 19 Jan 2007 17:06:24 GMT From: Jeremy.Gibbons@comlab.ox.ac.uk To: categories@mta.ca Subject: categories: Call for participation and abstracts: BCTCS, Oxford, 2-5 Apr Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: RO X-Status: X-Keywords: X-UID: 82 (apologies for any duplicate cross-postings you may receive) +--------------------------------------------------------------------+ 23rd British Colloquium for Theoretical Computer Science BCTCS 2007 2-5 April 2007 St Anne's College, Oxford http://cms.brookes.ac.uk/bctcs2007/ The purpose of BCTCS is to provide a forum in which researchers in theoretical computer science can meet, present research findings, and discuss developments in the field. It also aims to provide an environment in which PhD students can gain experience in presenting their work, and benefit from contact with established researchers. SCOPE All aspects of theoretical computer science, including automata theory, algorithms, complexity theory, semantics, formal methods, concurrency, types, languages and logics. Computer scientists and mathematicians are welcome to attend, as are participants from outside the UK. PROGRAMME The programme will consist of nearly 3 days worth of invited and contributed talks, beginning at 5.30pm on Monday 2nd April and concluding at 1pm on Thursday 5th April 2007. The abstracts of the talks will be published in the Bulletin of the European Association for Theoretical Computer Science (EATCS). The invited speakers are as follows: Dimitris Achlioptas, University of California, Santa Cruz, U.S.A. "Random Constraint Satisfaction Problems: from Physics to Algorithms" Steven Alpern, The London School of Economics and Political Science "Search Games and Utilitarian Postman Paths on Networks" Julian Bradfield, University of Edinburgh (BCS-FACS Lecturer in Formal Methods) Georg Gottlob, University of Oxford "Living with Computational Complexity" (This is Prof. Gottlob's inaugural lecture at Oxford University.) Bob Harper, Carnegie Mellon University, U.S.A. Richard Jozsa, University of Bristol Kristina Vuskovic, University of Leeds (LMS Lecturer in Discrete Mathematics) LOCATION The 2007 colloquium will be held at St Anne's College, Oxford, one of the colleges of the University of Oxford, and hosted by the computing departments of both Oxford Brookes and Oxford universities, Oxford itself is known as the "City of Dreaming Spires", and has been home to both royalty and scholars for over 800 years. REGISTRATION Registration for BCTCS2007 is open, via the web page. The deadline for registration and submission of abstracts for proposed talks is 16th February 2007. The registration fee is 340 UK pounds, including accommodation and meals, and the day rate is 145 UK pounds. A number of free registrations for UK-based PhD students are available. SPONSORS The colloquium is sponsored by EPSRC, BCS-FACS, and also the London Mathematical Society. FURTHER DETAILS Google search - BCTCS 2007 Web page - http://cms.brookes.ac.uk/bctcs2007/ +--------------------------------------------------------------------+ From rrosebru@mta.ca Fri Jan 19 19:42:59 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Fri, 19 Jan 2007 19:42:59 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1H83M2-0002Xe-6X for categories-list@mta.ca; Fri, 19 Jan 2007 19:41:06 -0400 Date: Fri, 19 Jan 2007 15:38:08 -0500 (EST) Subject: categories: Postdoctoral position at U. Ottawa From: rblute@uottawa.ca To: categories@mta.ca MIME-Version: 1.0 Content-Type: text/plain;charset=iso-8859-1 Content-Transfer-Encoding: 8bit Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: RO X-Status: X-Keywords: X-UID: 83 Research Fellow/Postdoc position in Category Theory, Logic and Computation, University of Ottawa The Logic Group in the Department of Mathematics and Statistics at the University of Ottawa is looking to hire at least one research fellow/postdoc beginning in September, 2007. The positions are in any area of category theory, categorical logic, and theoretical computer science. Research fellows / postdocs will participate in the activities of the Logic and Foundations of Computation Group. This group includes faculty and students from several different Ottawa-area universities. In the Math Department, the Logic Group currently includes 4 faculty members (R. Blute, P. Hofstra, P.E. Parent and P. Scott), as well as a number of postdocs and graduate students. For more information about our team, see http://www.site.uottawa.ca/~phil/lfc/. The research fellowships/postdocs are initially for one year, with a possible renewal for a second year. Duties include research and the teaching of two one-semester courses. Potential applicants should contact one of us: Richard Blute (rblute at uottawa.ca) Pieter Hofstra (phofstra at uottawa.ca) Paul-Eugene Parent (pparent at uottawa.ca) Philip Scott (phil at site.uottawa.ca) immediately by email to indicate their interest. They should then also send a curriculum vitae, a research plan, and arrange for three confidential letters of recommendation, with one addressing teaching, to be sent to Professor Victor Leblanc, Chairman, Department of Mathematics and Statistics, University of Ottawa, Ottawa, ON Canada, K1N 6N5. Applicants are also encouraged to include up to three copies of their most significant publications. Those who have already applied for a position will of course be considered and do not have to re-send an application, although it would be wise to send one of us an email. From rrosebru@mta.ca Sat Jan 20 13:24:19 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Sat, 20 Jan 2007 13:24:19 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1H8JrL-0006zA-Me for categories-list@mta.ca; Sat, 20 Jan 2007 13:18:31 -0400 Date: Sat, 20 Jan 2007 15:35:34 +0000 (GMT) From: Martin Hyland To: categories@mta.ca Subject: categories: Eilenberg: seeking a copy of lecture notes MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: RO X-Status: X-Keywords: X-UID: 84 Bill Lawvere has drawn my attention to a significant moment in the history of the application of the ideas of algebraic theories to computer science of which I was quite unaware. In 1967 Eilenberg gave the four Colloquium Lectures at the Summer Meeting of the AMS in Toronto. Available details are as follows. August 29-September 1, 1967, Toronto, Ontario, Canada. Samuel Eilenberg, Columbia University. Universal algebras and the theory of automata. Contrary to what one might suppose this material did not appear in any of the books or papers of Eilenberg or his collaborators; but lecture notes were distributed at the meeting. Does anyone have a copy which they could make available? The notes would be of great interest right now from a historical point of view for a paper by John Power and me. But it seems likely that formulations in the notes would be of wider interest as by the time (at least) of the notes it seems that Eilenberg had digested the material in Lawvere's thesis. In hope, Martin Hyland From rrosebru@mta.ca Sat Jan 20 13:24:19 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Sat, 20 Jan 2007 13:24:19 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1H8Jqs-0006wL-1u for categories-list@mta.ca; Sat, 20 Jan 2007 13:18:02 -0400 Date: Fri, 19 Jan 2007 22:15:19 -0500 (EST) From: Michael Barr To: categories@mta.ca Subject: categories: Re: Exactness without pullbacks MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: RO X-Status: X-Keywords: X-UID: 85 Of course I meant the definition in LNM#236. However, I don't have the original source at home anyway, so I would have to wait to check it. From rrosebru@mta.ca Mon Jan 22 15:22:28 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Mon, 22 Jan 2007 15:22:28 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1H94Zs-0003PY-Af for categories-list@mta.ca; Mon, 22 Jan 2007 15:11:36 -0400 From: Philippe Gaucher To: categories@mta.ca Subject: categories: preprint : Towards an homotopy theory of process algebra Date: Mon, 22 Jan 2007 12:18:05 +0100 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: O X-Status: X-Keywords: X-UID: 86 Author : Philippe Gaucher Title : Towards an homotopy theory of process algebra Abstract : This paper proves that labelled flows are expressive enough to contain all process algebras which are a standard model for concurrency. More precisely, we construct the space of execution paths and of higher dimensional homotopies between them for every process name of every process algebra with any synchronization algebra using a notion of labelled flow. This interpretation of process algebra satisfies the paradigm of higher dimensional automata: one non-degenerate full $n$-dimensional cube (no more no less) in the underlying space of the time flow corresponding to the concurrent execution of $n$ actions. This result will enable us in future papers to develop an homotopical approach of process algebras. Indeed, several homological constructions related to the causal structure of time flow are possible only in the framework of flows. URL : my web page or arxiv math.AT/0701552. From rrosebru@mta.ca Mon Jan 22 15:36:55 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Mon, 22 Jan 2007 15:36:55 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1H94wR-0006Bu-NC for categories-list@mta.ca; Mon, 22 Jan 2007 15:34:55 -0400 Subject: categories: Re: Exactness without pullbacks From: Eduardo Dubuc Date: Mon, 22 Jan 2007 14:04:54 -0300 (ART) To: categories@mta.ca MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: O X-Status: X-Keywords: X-UID: 87 M. Barr wrote (in part, concerning the question of defining the stability of a regular epi under pull-backs without pull-backs) > > However, one > possibility that I have known of for a long time but not written about > is > to suppose that when A --> B is regular epic and B' --> B is > arbitrary and > you look at all pairs A' --> A, A' --> B' that make the evident square > commute, then the family of all those A' --> B' is an effective epic > family. In that category, a pullback, if it exists, is terminal. > refer to this property as (*) Well, (*) is the same of what I wrote in my posting in the subject: (*): > you can say that a strict epi is "stable under pullbacks" also in > the > absence of pullbacks: > > Z_i -------> X > | | > |f_i |f > \/ h \/ > Z --------> Y > > a strict epi f is universal if given any h there exists a strict > epi family f_i as indicated in the diagram. > > this exactness property is as good as stability under pullbacks > see the links > > http://arXiv.org/abs/math/0611701 > > http://arXiv.org/abs/math/0612727 > Of course, it is the same if we are talking of the same thing. That we are. When I say "strict", I mean it in the sense of SGA4 Expose I, 10.2 10.3, and we should assume that it coincides with what M. Barr calls "effective". Contrary to M. Barr terminology, "effective" is also utilizad in SGA4, presicely, when the kernel pair exists ! Concerning the above notion (*) of "stability under pull-backs without pull-backs" (an instance of "universality"), it is also defined in SGA4 Expose II 2.5, and it is simply the following: an arrow F: X ---> Y (singleton family) is a strict universal epimorphism if it is a cover for the canonical topology. In Proposition 2.6 it is stablished the characterization of strict universal epimorphisms by the property (*) above. e.d. From rrosebru@mta.ca Fri Jan 26 20:09:51 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Fri, 26 Jan 2007 20:09:51 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1HAayh-0003AA-6E for categories-list@mta.ca; Fri, 26 Jan 2007 19:59:31 -0400 Subject: categories: terminology From: Eduardo Dubuc To: categories@mta.ca Date: Fri, 26 Jan 2007 20:30:49 -0300 (ART) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: RO X-Status: X-Keywords: X-UID: 88 hello: Given a set CC of objects in a topos EE, consider the following property: " X no= empty iff exists C \in CC, hom(C, X) no= empty " example; CC = a set of generators Has (this property) already a name ? If not, can you suggest one ? Any answer will be welcome. (Notice that if CC is a set of points (instead of objects) we say that there are enough points) Thanks Eduardo J. Dubuc From rrosebru@mta.ca Sat Jan 27 10:09:28 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Sat, 27 Jan 2007 10:09:28 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1HAo8W-0001B1-5l for categories-list@mta.ca; Sat, 27 Jan 2007 10:02:32 -0400 Mime-Version: 1.0 (Apple Message framework v752.2) Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit From: Ross Street Subject: categories: Max Date: Sat, 27 Jan 2007 11:27:23 +1100 To: Categories Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: RO X-Status: X-Keywords: X-UID: 89 I have very sad news for the categorical community. Max Kelly died yesterday 26 January 2007. I believe it was a heart attack. Ross From rrosebru@mta.ca Sun Jan 28 10:34:03 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Sun, 28 Jan 2007 10:34:03 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1HBAwU-0006y7-Nf for categories-list@mta.ca; Sun, 28 Jan 2007 10:23:38 -0400 Subject: categories: Re: terminology Date: Sat, 27 Jan 2007 12:06:57 -0500 From: wlawvere@buffalo.edu To: categories@mta.ca MIME-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 8bit Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: RO X-Status: X-Keywords: X-UID: 90 Dear Eduardo and everybody: In one of your papers you used the term Nullstellensatz for a special case (in some sense an "algebraically closed"case). I propose to use that term in this more general case. The parameters for various traditional cases can be perhaps expessed by an essential connected morphism of toposes E->S. That is, a full inclusion of "relatively discrete" into "relatively continuous" which has both left adjoint ("connected components") and right adjoint ("points"). In that context there is a natural map from points to components; if it is epic, we can say that the Nullstellensatz holds for E->S. If S is just the category of abstract sets, one could think of E as algebraically closed if the Nullstellensatz holds. But as seems implicit in Galois theory, for algebraic geometry over a non-algebraically closed K, the appropriate base topos S consists not of abstract sets, but rather of sheaves on C = the opposite of the category of finite extensions of K, with every map covering. If E is the topos of sheaves on (finitely generated K-algebras )^op with respect to a topology that restricts to the above on C, I believe we have a classical example of both your formulation and mine. Bill PS There are other stronger results that also could be called Nullstellensatz, involving another topos F between E and S, such as the one generated by algebras that are finite dimensional as K-vector spaces, or one suggested by Birkhoff's SDI theorem. What is the appropriate statement for these results ? Quoting Eduardo Dubuc : > hello: > > Given a set CC of objects in a topos EE, consider the following > property: > > " X no= empty iff exists C \in CC, hom(C, X) no= empty " > > example; CC = a set of generators > > Has (this property) already a name ? > > If not, can you suggest one ? > > Any answer will be welcome. > > (Notice that if CC is a set of points (instead of objects) we say > that > there are enough points) > > Thanks Eduardo J. Dubuc > > > > From rrosebru@mta.ca Sun Jan 28 10:34:03 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Sun, 28 Jan 2007 10:34:03 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1HBAuA-0006qV-Le for categories-list@mta.ca; Sun, 28 Jan 2007 10:21:14 -0400 Subject: categories: Re: Max Date: Sat, 27 Jan 2007 10:31:58 -0500 From: wlawvere@buffalo.edu To: Categories MIME-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 8bit Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: RO X-Status: X-Keywords: X-UID: 91 I am deeply saddened by the loss of Max. In our field he was a rock of reliability and a fountain of imagination. I will miss my lively, warm, kind, and sometimes mischievous friend. Bill Lawvere Quoting Ross Street : > I have very sad news for the categorical community. > Max Kelly died yesterday 26 January 2007. > I believe it was a heart attack. > > Ross > > > > From rrosebru@mta.ca Sun Jan 28 10:34:03 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Sun, 28 Jan 2007 10:34:03 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1HBAxi-00071F-8p for categories-list@mta.ca; Sun, 28 Jan 2007 10:24:54 -0400 Date: Sat, 27 Jan 2007 08:02:36 -0200 (BRST) Subject: categories: WoLLIC'2007 - CfP From: ruy@cin.ufpe.br To: wollic@cin.ufpe.br MIME-Version: 1.0 Content-Type: text/plain;charset=iso-8859-1 Content-Transfer-Encoding: 8bit Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: RO X-Status: X-Keywords: X-UID: 92 [** sincere apologies for duplicates **] Call for Papers 14th Workshop on Logic, Language, Information and Computation (WoLLIC'2007) Rio de Janeiro, Brazil July 2-5, 2007 WoLLIC is an annual international forum on inter-disciplinary research involving formal logic, computing and programming theory, and natural language and reasoning. Each meeting includes invited talks and tutorials as well as contributed papers. The Fourteenth WoLLIC will be held in Rio de Janeiro, Brazil, from July 2 to July 5, 2007, and sponsored by 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 European Association for Theoretical Computer Science (EATCS), the Sociedade Brasileira de Computacao (SBC), and the Sociedade Brasileira de Logica (SBL). PAPER SUBMISSION Contributions are invited on all pertinent subjects, with particular interest in cross-disciplinary topics. Typical but not exclusive areas of interest are: foundations of computing and programming; novel computation models and paradigms; broad notions of proof and belief; formal methods in software and hardware development; logical approach to natural language and reasoning; logics of programs, actions and resources; foundational aspects of information organization, search, flow, sharing, and protection. Proposed contributions should be in English, and consist of a scholarly exposition accessible to the non-specialist, including motivation, background, and comparison with related works. They must not exceed 10 pages (in font 10 or higher), with up to 5 additional pages for references and technical appendices. The paper's main results must not be published or submitted for publication in refereed venues, including journals and other scientific meetings. It is expected that each accepted paper be presented at the meeting by one of its authors. Papers must be submitted electronically at www.cin.ufpe.br/~wollic/wollic2007/instructions.html A title and single-paragraph abstract should be submitted by February 23, and the full paper by March 2 (firm date). Notifications are expected by April 13, and final papers for the proceedings will be due by April 27 (firm date). PROCEEDINGS Proceedings, including both invited and contributed papers, will be published in advance of the meeting. Publication venue: Springer's Lecture Notes in Computer Science. INVITED SPEAKERS: Veronique Cortier (LORIA Nancy) Martin Escardo (Birmingham) Georg Gottlob (Oxford) Achim Jung (Birmingham) Louis Kauffman (U Illinois Chicago) Sam Lomonaco (U Maryland Baltimore) Paulo Oliva (London/QM) John Reif (Duke) Yde Venema (Amsterdam) STUDENT GRANTS ASL sponsorship of WoLLIC'2007 will permit ASL student members to apply for a modest travel grant (deadline: April 1, 2007). See www.aslonline.org/studenttravelawards.html for details. IMPORTANT DATES February 23, 2007: Paper title and abstract deadline March 2, 2007: Full paper deadline (firm) April 12, 2007: Author notification April 26, 2007: Final version deadline (firm) PROGRAM COMMITTEE Samson Abramsky (U Oxford) Michael Benedikt (Bell Labs) Lars Birkedal (ITU Copenhagen) Andreas Blass (U Michigan) Thierry Coquand (Chalmers U, Goteborg) Jan van Eijck (CWI, Amsterdam) Marcelo Finger (U Sao Paulo) Rob Goldblatt (Victoria U, Wellington) Yuri Gurevich (Microsoft Redmond) Hermann Haeusler (PUC Rio) Masami Hagiya (Tokyo U) Joseph Halpern (Cornell U) John Harrison (Intel UK) Wilfrid Hodges (U London/QM) Phokion Kolaitis (IBM Almaden Research Center) Marta Kwiatkowska (U Birmingham) Daniel Leivant (Indiana U) (Chair) Maurizio Lenzerini (U Rome) Jean-Yves Marion (LORIA Nancy) Dale Miller (Polytechnique Paris) John Mitchell (Stanford U) Lawrence Moss (Indiana U) Peter O'Hearn (U London/QM) Prakash Panangaden (McGill, Montreal) Christine Paulin-Mohring (Paris-Sud, Orsay) Alexander Razborov (Steklov, Moscow) Helmut Schwichtenberg (Munich U) Jouko Vaananen (U Helsinki) ORGANISING COMMITTEE Marcelo da Silva Correa (U Fed Fluminense) Renata P. de Freitas (U Fed Fluminense) Ana Teresa Martins (U Fed Ceara') Anjolina de Oliveira (U Fed Pernambuco) Ruy de Queiroz (U Fed Pernambuco, co-chair) Petrucio Viana (U Fed Fluminense, co-chair) WEB PAGE www.cin.ufpe.br/~wollic/wollic2007 --- From rrosebru@mta.ca Sun Jan 28 22:01:12 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Sun, 28 Jan 2007 22:01:12 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1HBLie-0004Jd-VW for categories-list@mta.ca; Sun, 28 Jan 2007 21:54:05 -0400 Subject: categories: Re: Max From: Eduardo Dubuc Date: Sun, 28 Jan 2007 13:39:02 -0300 (ART) To: categories@mta.ca (Categories) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: RO X-Status: X-Keywords: X-UID: 93 I am deeply saddened by the death of Max Kelly. When I saw the subject in Ross posting, and before opening the message, my heart already felt anguish. I am more saddened with his loss that what I have been by the loss of any other member of our category theory community. In fact, I loved Max. I admired his courage, his independence of thought, his lack of hypocrisy, and I loved him simply by the way he was. I am proud that he considered me his friend. For me, our community is not the same without Max. Eduardo J. Dubuc > > I have very sad news for the categorical community. > Max Kelly died yesterday 26 January 2007. > I believe it was a heart attack. > > Ross > > From rrosebru@mta.ca Mon Jan 29 16:45:46 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Mon, 29 Jan 2007 16:45:46 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1HBdDa-0002qM-Tb for categories-list@mta.ca; Mon, 29 Jan 2007 16:35:11 -0400 From: "George Janelidze" To: "Categories" References: Subject: categories: Re: Max Date: Mon, 29 Jan 2007 13:15:06 +0200 MIME-Version: 1.0 Content-Type: text/plain;charset="iso-8859-1" Content-Transfer-Encoding: 7bit Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: RO X-Status: X-Keywords: X-UID: 94 Gregory Maxwell Kelly was one of the great mathematicians of our time, so perfect in his research and vision of mathematics, and in every aspect of academic life. And he was so exceptionally kind to everyone. It is hard to imagine that Max is not with us anymore, and it is a great pain for his family and for all of us, his friends and colleagues... George Janelidze ----- Original Message ----- From: "Ross Street" To: "Categories" Sent: Saturday, January 27, 2007 2:27 AM Subject: categories: Max > I have very sad news for the categorical community. > Max Kelly died yesterday 26 January 2007. > I believe it was a heart attack. > > Ross From rrosebru@mta.ca Mon Jan 29 16:45:46 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Mon, 29 Jan 2007 16:45:46 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1HBdES-0002w7-I1 for categories-list@mta.ca; Mon, 29 Jan 2007 16:36:04 -0400 Subject: categories: Max Kelly, a master of coherence To: categories@mta.ca Date: Mon, 29 Jan 2007 16:11:43 -0400 (AST) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit From: rjwood@mathstat.dal.ca (RJ Wood) Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: RO X-Status: X-Keywords: X-UID: 95 We would like to add to Bill and Eduardo's letters also our feelings of deep sadness at Max's death. Max Kelly's Last Work ===================== In due course Max's last work will appear in a four-author paper. While it is not usual for coauthors to divulge who contributed what to a paper the present circumstances seem to warrant such, as an appreciation of Max's extraordinary talents and tenacity. Carboni, Kelly, Walters, and Wood, [CKWW] have for some time been extending the Carboni and Walters notion of `cartesian bicategory' to the general case of bicategories that are not necessarily locally ordered. A cartesian bicategory B ultimately has a tensor product, a pseudofunctor *:BxB--->B that is naively associative and unitary. It is natural to ask whether such (B,*) is a monoidal bicategory, in other words a one-object tricategory in the sense of [Coherence for Tricategories; Gordon, Power, and Street]=[GPS]. Early in 2005 [CKWW] had shown that _if_ a bicategory A with finite `products' -x- and 1, in the bilimit sense, has (A,x) a monoidal bicategory then a cartesian bicategory B has (B,*) monoidal. In the course of polishing the paper it came to Max's attention that nobody had _proved_ the Theorem: A bicategory with finite products is monoidal. Nobody doubted the truth of this. In fact, experts in higher dimensional category theory said that if it were not true then the definition of tricategory is wrong! But when you consider the rather large amount of data that must be assembled and the many equations (some merely implicit in words such as pseudonatural and modification) that must be verified from the apparently rather weak universal property of finite products in the bilimit sense, it seemed like a rather thankless task to write out the details. This was to Max a completely unacceptable state of affairs. If nobody doubts the statement then it must be possible to find a good proof! Now Max had no intention of redrawing any of the diagrams in [GPS]. For the last few years Max, with little central vision left as a result of macular degeneration, has been doing Mathematics using an 8-fold magnification monitor. This allowed him to see only a few square centimetres of a page at a time. Many [GPS] diagrams consume an entire page. His proof, that we were privileged to receive in the last few weeks, has _no_ diagrams (though doubtless we will incorporate a few in a publishable version of the paper). Max attributed the key idea in his proof to Ross Street. Briefly, this is how it goes: For X a finite family of objects in the bicategory A, write A(X) for the bicategory of product cones over X. Thus an object of A(X) consists of an object b of A, together with a family of arrows p_i:b--->X_i, such that for all a, the induced functor A(a,b)--->\Pi A(a,X_i) is an equivalence of categories. Lemma: !:A(X)--->1 is a biequivalence (Recall that to say B--->1 is a biequivalence is to say that: i) there is an object b in B ii) for any objects c and d in B, there is an arrow f:c--->d iii) for any arrows g,h:c--->d in B, there is a unique 2-cell g--->h. It follows that in a bicategory biequivalent to 1, every arrow is an equivalence and every 2-cell is an isomorphism.) Next, Max observes that if A has finite products then, for any B, the bicategory [B,A] of pseudofunctors, pseudonatural transformations, and modifications also has finite products, given `pointwise' by the products of A. -x- is an object of [A^2,A]. We can use (a x b) x c and a x (b x c) as names for objects in [A^3,A] and applying the Lemma to [A^3,A](a,b,c) deduce the existence of the associator equivalence, pseudonatural in a,b, and c. The associator gives rise to two arrows (abbreviating somewhat) ((ab)c)d ===> a(b(cd)) in [A^4,A](a,b,c,d) and between these we have a unique invertible modification, the \pi of [GPS]. The coherence of \pi is chiefly the Stasheff non-abelian 4-cocycle condition (again see [GPS]) and for this we need only apply the Lemma to [A^5,A](a,b,c,d,e) to see that the two modifications in question are equal. Of course the other data and equations are handled with similar appeals to the Lemma. Max was not content to stop here. In his last few days he had been learning the rather subtle definition of _symmetric_ monoidal bicategory and constructed the requisite braiding equivalence and syllepsis isomorphism for a bicategory with finite products. Everything follows from the universal property but Max has shown us _how_ so that we can calculate with these things. His insights show us the way to deal with coherence issues arising from birepresentability generally and weak n-representability when the need arises. Max's personal copy of [GPS] was autographed by Ross with the words ``To Max Kelly, a master of coherence''. Yes, he was. Aurelio Carboni, Robert Walters, and Richard Wood From rrosebru@mta.ca Tue Jan 30 20:32:47 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Tue, 30 Jan 2007 20:32:47 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1HC3CF-0005Y5-DR for categories-list@mta.ca; Tue, 30 Jan 2007 20:19:31 -0400 Subject: categories: ETAPS 2007: Call for Participation From: =3D?ISO-8859-1?Q?Jo=3DE3o?=3D Saraiva To: categories@mta.ca Content-Type: text/plain; charset=3DUTF-8 Date: Tue, 30 Jan 2007 11:14:02 +0000 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: RO X-Status: X-Keywords: X-UID: 96 ***************************************************************** *** *** *** ETAPS 2007 *** *** March 24 - April 1, 2007 *** *** Braga, Portugal *** *** *** *** http://www.di.uminho.pt/etaps07/ *** *** *** *** CALL FOR PARTICIPATION *** *** *** *** Early Registration Deadline: 12th February, 2007 *** *** *** ***************************************************************** The European Joint Conferences on Theory and Practice of Software (ETAPS) is the primary European forum for academic and industrial researchers working on topics related to Software Science. It is a confederation of five main conferences, several satellite workshops and other events. ETAPS 2007 is taking place in Braga, Portugal. Braga, capital of the Minho province, is an ancient city in the heart of the green and fertile region known as the Costa Verde. The region is known for its attractiveness in terms of climate, gastronomy, prices, and culture. Braga is known for its barroque churches and splendid 18th century houses. The old city is solemn and antique, but animated with commercial activity and academic life. =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D 5 Conferences - 18 Satellite Workshops - 3 Tutorials - Tool Demonstrations =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D ------------------------------------------------------------------------- Main Conferences ------------------------------------------------------------------------- CC 2007: International Conference on Compiler Construction http://cc2007.cs.brown.edu/ ESOP 2007: European Symposium on Programming http://rap.dsi.unifi.it/esop07/ FASE 2007: Fundamental Approaches to Software Engineering http://fase07.di.fc.ul.pt FOSSACS 2007: Foundations of Software Science and Computation Structures http://www2.in.tum.de/~seidl/fossacs07/ TACAS 2007: Tools and Algorithms for the Construction and Analysis of Systems http://www.doc.ic.ac.uk/tacas07/ ----------------------------------------------------------------------- Invited Speakers ----------------------------------------------------------------------- ETAPS 2007: Rance Cleaveland - University of Maryland, USA ETAPS 2007: Bertrand Meyer - ETH Z=C3=BCrich, Switzerland CC 2007: Don Batory - University of Texas at Austin, USA ESOP 2007: Andrew Pitts - Cambridge University, UK FASE 2007: Jan Bosch - Nokia, Finland FOSSACS 2007: Radha Jagadeesan - DePaul University, USA TACAS 2007: K. Rustan M. Leino - Microsoft Research, USA Further invited speakers are giving talks in the satellite workshops. ----------------------------------------------------------------------- Satellite Workshops ----------------------------------------------------------------------- ACCAT: Applied and Computational Category Theory http://tfs.cs.tu-berlin.de/workshops/accat2007/ AVIS: Int. Workshop on Automated Verification of Infinite-State Systems http://chacs.nrl.navy.mil/AVIS07 Bytecode: Bytecode Semantics, Verification, Analysis and Transformation http://www.sci.univr.it/~spoto/Bytecode07/ COCV: Sixth Workshop on Compiler Optimization Meets Compiler Verification http://pes.cs.tu-berlin.de/cocv2007/ FESCA: Formal Foundations of Embedded Software and Component-Based Software Architectures http://palab.dcs.kcl.ac.uk/fesca/ FinCo: Foundations of Interactive Computation http://www.cs.brown.edu/sites/finco07/ GT-VMT: Int. Workshop on Graph Transformation and Visual Modeling Techniques http://www.cs.le.ac.uk/events/GTVMT07/ HAV: Heap Analysis and Verification http://www.cs.tau.ac.il/~msagiv/hav.html HFL: Hardware design using Functional Languages http://hfl07.hflworkshop.org/ LDTA: Seventh Workshop on Language Descriptions, Tools and Applications http://www.di.uminho.pt/ldta07 MBT: Third Workshop on Model Based Testing http://react.cs.uni-sb.de/mbt2007/ MOMPES: Model-based Methodologies for Pervasive and Embedded Software http://www.di.uminho.pt/mompes OpenCert: Foundations and Techniques for Open Source Software Certification http://opencert.iist.unu.edu/ QAPL: Fifth Workshop on Quantitative Aspects of Programming Languages http://www.cse.yorku.ca/qapl07 SC: Software Composition http://ssel.vub.ac.be/sc2007 SLA++P: Model-driven High-level Programming of Embedded Systems http://web.uni-bamberg.de/wiai/gdi/SLAP07/ TERMGRAPH: Fourth International Workshop on Computing with Terms and Graphs http://www.termgraph.org.uk WITS: Seventh Workshop on Issues in the Theory of Security http://www.dsi.unive.it/IFIPWG1_7/wits2007.html ----------------------------------------------------------------------- Tutorials ----------------------------------------------------------------------- Program Transformation with Stratego/XT Martin Bravenboer (Utrecht University) and Eelco Visser (Delft University of Technology) Beyond the Generators: Practical Techniques for Real-World Software Generation Anthony M. Sloane (Macquarie University) Mobility, Ubiquity, and Security Gilles Barthe (INRIA), David Pichardie (IRISA), David Aspinall (Univ. of Edinburgh), Peter M=C3=BCller (ETH Zurich), Lennart Beringer (LMU Munich) and Joe Kiniry (UC Dublin) ----------------------------------------------------------------------- Tool Demonstrations ----------------------------------------------------------------------- Demonstrations of tools presenting advances on the state of the art have been selected and are integrated in the programmes of the main conferences. ----------------------------------------------------------------------- Registration and Contact Details ----------------------------------------------------------------------- For online registration, please visit http://www.di.uminho.pt/etaps07/ and go to menu item "Registration". Contact details are available at the menu item "Contact us". In case of any questions not addressed on the web pages, please email etaps07@di.uminho.pt. From rrosebru@mta.ca Wed Jan 31 12:45:33 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Wed, 31 Jan 2007 12:45:33 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1HCIV0-0000Ya-G8 for categories-list@mta.ca; Wed, 31 Jan 2007 12:39:54 -0400 Date: Wed, 31 Jan 2007 01:52:33 -0500 From: "Fred E.J. Linton" MIME-Version: 1.0 To: categories@mta.ca Subject: categories: Address change reminder Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: O X-Status: X-Keywords: X-UID: 97 I've just become aware that some folks may still believe, in error, that some variation of the now defunct e-mail address 0004142427/FEJLINTON@MCIMAIL.COM remains valid for me (perhaps name only, or number only, w/ or w/o leading zeros). Please be aware that, as of the end of 30 June 2003, MCI Mail ceased to exist, the restructuring of MCI/WorldCom having cut off its life-support. Instead, please use my university e-mail address, which is FLinton@Wesleyan.edu , or the secondary, back-up, address: fejlinton@usa.net . Many thanks. -- Fred Linton --- From rrosebru@mta.ca Wed Jan 31 13:18:50 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Wed, 31 Jan 2007 13:18:50 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1HCJ4g-0004dV-Ml for categories-list@mta.ca; Wed, 31 Jan 2007 13:16:46 -0400 To: categories@mta.ca Subject: categories: Max Kelly; Funeral Notice From: Ross Street Date: Wed, 31 Jan 2007 13:35:35 +1100 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain;charset=WINDOWS-1252; format=flowed Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: RO X-Status: X-Keywords: X-UID: 98 Sydney Morning Herald (Wed 31 Jan 2007) Funeral Notice KELLY, Gregory Maxwell (Max) Professor. =97 January 26, 2007, suddenly, late of Pymble. Dearly loved husband of Imogen, loving father of Dominic, Martin, Catherine, Simon and father-in-law of Narrelle, Leisa, Albert and Cathryn. Devoted grandfather of Caitlin, Tara, Zachary, James, Vanessa, Jacob, Rebecca, Sinead, Morgan and Madison. Loving brother of Michael, fond cousin of Frieda. A Requiem Mass for MAX will be celebrated at St. Anthony in the Field Catholic Church, Myoora Road, Terry Hills, on Friday (February 2, 2007), commencing at 1 p.m. At the conclusion of the Mass, the cortege will proceed to Macquarie Park Cemetery. No flowers by request, donations may be made to The Macular Degeneration Foundation 447 Kent Street, Sydney 2000. www.mdfoundation.com.au MAURER Funeral Directors 9413 1377 From rrosebru@mta.ca Wed Jan 31 17:21:14 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Wed, 31 Jan 2007 17:21:14 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1HCMo5-0005UG-PU for categories-list@mta.ca; Wed, 31 Jan 2007 17:15:53 -0400 Date: Wed, 31 Jan 2007 15:17:42 -0500 From: joyal.andre@uqam.ca To: categories@mta.ca Subject: categories: Letter to Max MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: O X-Status: X-Keywords: X-UID: 99 Dear Max, I feel deeply sad that you have left. Now that you are gone, I realise how much you mean to me. I regret not telling you that. I wish to repair that by writing you this letter. If I send it to Imogen and to your friends, it will reach you in some way. Your work has been a constant source of inspiration for me. It combines beauty, rigor and depth. It is fundamental, I use it every day. It will last forever. You were a great mathematician. I also want to thank you for inviting me to Australia. I did some of my best work there. You were a great host. I made many friends. I wish we could meet again. I will talk with you in my dreams. Yours, Andre From rrosebru@mta.ca Wed Jan 31 19:33:21 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Wed, 31 Jan 2007 19:33:21 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1HCOt9-0002VN-Nu for categories-list@mta.ca; Wed, 31 Jan 2007 19:29:15 -0400 Date: Wed, 31 Jan 2007 13:23:33 -0500 From: tholen@mathstat.yorku.ca To: categories@mta.ca Subject: categories: Max MIME-Version: 1.0 Content-Type: text/plain;charset=ISO-8859-1;format="flowed" Content-Disposition: inline Content-Transfer-Encoding: 7bit Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: O X-Status: X-Keywords: X-UID: 100 Max Kelly was not only a power house of categorical understanding, but he also taught us how to combine beauty with rigour and thoroughness in his mathematical writings (see, for example, Richard Wood's recent message!) and thereby rendered an enormous service to the reputation of category theory. In addition to creating a world centre for categories at Sydney, with his willingness to spend long periods of time at numerous places in the world he was (together with Saunders Mac Lane) also the prime ambassador for category theory for many years in many countries, where he would not only give plenty of his time but also never fail to fully engage himself in the local language and culture. Early in my career I had the great privilege to benfit from Max's visits in Germany. Like many others, I will always remain very grateful to him for everything that I learned from him at that time, and for being such a candid and inspiring leader in our community for over forty years. Walter Tholen.