Date: Tue, 5 Dec 1995 22:41:14 -0400 (AST)
Subject: paper on equivariant homotopy
Date: Mon, 4 Dec 1995 18:06:48 GMT
From: Manuel Bullejos <bullejos@goliat.ugr.es>
The following paper can be obained from my www page with address
http:\\www.ugr.es\~bullejos
\title{On the equivariant 2-type of a $G$-space}
\begin{abstract}
A classical theorem of Mac Lane and Whitehead states that
the homotopy type of a topological space with trivial homotopy at
dimensions 3 and greater can be re\-con\-struct\-ed from its $\pi_1$ and
$\pi_2$, and a cohomology class $k_3\in H^3(\pi_1,\pi_2)$. More recently,
Moerdijk and Svensson suggested the possibility of using Bredon cohomology
to extend this result to the equivariant case, that is, for spaces $X$
equipped with an action by a fixed group $G$. In this paper we carry out
this suggestion and prove an analogue of the classical result in the
equivariant case.
\end{abstract}
Date: Tue, 5 Dec 1995 22:42:24 -0400 (AST)
Subject: information about postdoctoral position at Sydney
Date: Tue, 5 Dec 95 15:33:09 +1100
From: Max Kelly <kelly_m@maths.su.oz.au>
Postdoctoral Fellowship at the University of Sydney
As a result of a three-year Australian Research Grant awarded to Max Kelly
for research into "two-dimensional universal algebra" - by which is meant
the study of structures borne, not just by sets, but by categories and the
like - there are funds available to support a position of Postdoctoral
Fellow at the University of Sydney for three years from the beginning of
1996. A copy of the formal advertisement sent to the Australian newspapers
appears below. (The salaries quoted are under review, and may before long
be increased by 2% if all goes well - but this is still uncertain.) Among
the good recent sources for getting some flavour of the subject as practised
at Sydney are:
R.Blackwell, G.M.Kelly, and A.J.Power, Two-dimensional monad theory,
J. Pure Appl. Algebra} 59 (1989), 1-41;
G.M.Kelly, S.Lack, and R.F.C.Walters, Coinverters and categories of fractions
for categories with structure, Applied Categorical Structures 1(1993), 95-102.
G.M.Kelly and A.J.Power, Adjunctions whose counits are coequalizers and
presentations of finitary enriched monads, J. Pure Appl. Algebra 89(1993),
163-179.
Note that appointments are made these days by committees that are bound by
very precise rules. No-one may be appointed who does not demonstrably possess
each of the essential qualifications - so applicants would be well-advised to
address these qualifications one-by-one and argue that they possess them.
Here is the formal advertisement that will appear in Australia next week:
__________________________
Post-doctoral Fellow (Fixed-term) School of Mathematics and Statistics
UNIVERSITY OF SYDNEY
The appointee is to assist in all aspects of an ARC-funded research project
on two-dimensional universal algebra - that is, the study of structures borne
by categories and the like.
A Ph.D. in mathematics, either awarded or shortly to be awarded, is an essential
qualification - as are a general familiarity with modern category theory,
including 2-categories and other enriched categories, together with some
experience of research into categories with structure or higher-dimensional
categories, and evidence of an outstanding capacity for the understanding of
mathematics at the highest level. Any familiarity with higher-dimensional
categories, including bicategories and tricategories, would be an advantage.
Appointment is for three years.
Further information from Prof. G.M. Kelly, Tel. +61-2-351-3796, email:
kelly_m@maths.su.oz.au
or from Assoc. Prof. C. Durrant, Tel. +61-2-351-3373, email:
durrant_c@maths.su.oz.au
Salary: Aus.Dollars 37345-40087
Closing date: 25 January 1996.
Please forward one copy of the application, quoting the reference
number A48/xx (the value of xx not yet known), and including curriculum
vitae, list of publications, and the names, addresses, and fax numbers
of at least three and not more than five referees, to
The Personnel Officer (Sciences Group)
Carslaw Building FO7
University of Sydney, NSW 2006
Australia
(or by fax to +61-2-351-5467)
_________________
Date: Tue, 5 Dec 1995 22:43:22 -0400 (AST)
Subject: New WWW Page: Logic-Related Conferences
Date: Tue, 5 Dec 95 09:32 EST
From: Doug Howe <howe@research.att.com>
LOGIC-RELATED CONFERENCES
http://www.research.att.com/lics/logic-confs.html
Over the last few years there has been a proliferation of
conferences that overlap in their technical scope with the Symposium
on Logic in Computer Science (LICS). These conferences are scheduled
with no prior coordination among them, which results quite often in
conflicts. For example, in 1995 LICS and FPCA were at exactly the
same time and the same place with no prior coordination.
In an attempt to address this situation, the LICS organization will
maintain a WWW page of conferences (including workshops) that have an
overlap with logic in computer science. The first half of the page is
a list of conferences and associated contacts. The second half is an
incomplete list of dates, some tentative and some fixed, for upcoming
meetings of these conferences.
If you are an organizer of one of these conferences and have some
information you would like included in the page, please send mail to
lics-request@research.att.com.
Date: Wed, 6 Dec 1995 12:48:46 -0400 (AST)
Subject: Dinatural exercise
Date: Wed, 6 Dec 1995 09:08:19 -0500
From: Peter Freyd <pjf@saul.cis.upenn.edu>
Is this new?
Let *A* be a locally small category. Let *D* be the category
whose objects are set-valued bifunctors on *A* (contravariant on
the first variable, covariant on the second) and whose maps are the
dinatural transformations. Then *A* is a groupoid.
Well, OK, what I mean is that dinaturals are closed under composition iff
*A* is a groupoid. (And, yes, this could all be done with the category of
sets replaced with a topos.)
I trust the following is old, but who has a reference?
If *A* is a groupoid then *D* is equivalent to the category of
presheaves on *A*.
Date: Wed, 6 Dec 1995 15:36:28 -0400 (AST)
Subject: Re: Dinatural exercise
Date: Wed, 06 Dec 1995 10:45:03 -0800
From: Vaughan Pratt <pratt@cs.Stanford.EDU>
From: Peter Freyd
[Let *D* be the category
whose objects are] set-valued bifunctors on *A* (contravariant on
the first variable, covariant on the second)
Two definitional/notational suggestions:
1. "sesquifunctors on A" for the objects of *D*
2. A -X A as a notation for *D*
The right-hand half of the X in -X is intended to suggest the
contravariant bit. One then has the following hierarchy.
A => B "functions" from A to B, viz. !A -o B
A -o B (homo)morphisms from A to B
A -X B sesquifunctors A\op x A -> B, dinaturally transformed
The first two come from linear logic, with !A = FU being interpreted as
the underlying object (e.g. underlying set) of A reflected back into
the category via F. F serves merely to make the underlying objects the
same "kind" as the objects they underlie, avoiding a proliferation of
kinds in order to keep linear logic typeless, or at least kindless.
Vaughan Pratt
Date: Wed, 6 Dec 1995 20:58:54 -0400 (AST)
Subject: LICS'96 Final Call for Papers + Correction
Date: Wed, 6 Dec 95 17:48 EST
From: Amy Felty <felty@research.att.com>
Eleventh Annual IEEE Symposium on
LOGIC IN COMPUTER SCIENCE
July 27-30, 1996, New Brunswick, New Jersey, USA
The complete call for papers is available from
http://www.research.att.com/lics/ and
ftp://research.att.com/dist/lics/
SUBMISSION DEADLINE: Papers must be received by December 13; late
submissions will not be considered.
CORRECTION: The postal code of the Program Chair in the original call
for papers is incorrect. The correct address is
Edmund M. Clarke
Department of Computer Science
Carnegie Mellon University
Pittsburgh, PA 15213, USA
Date: Thu, 7 Dec 1995 09:09:19 -0400 (AST)
Subject: associativity and commutativity of addition
Date: Thu, 7 Dec 1995 12:06:31 +0100
From: BOERGER <Reinhard.Boerger@FernUni-Hagen.de>
It is well-known that a category in which finite products exist and
coincide with finite coproducts (i.e. a zero object exists and the
binary product functor is naturally equivalent to the binary
coproduct functor) is semi- additive, i.e. enriched over the monoidal
closed category of commutative monoids. Conversely, in a semi-
additive category, every (existing) finite product is automatically a
finite coroduct in the canonical way (an vice versa). Now my student
Claus Kirschner observed that the proof of the latter fact does not
use associativity and commutativity of the addition. Strange enough,
together with the first fact this means: If a category with finite
products has an operation called "addition" with neutral element 0 on
each hom-set satisfying f0=0f=0 and the distributive laws, then the
addition is automatically associative and commutative. Has anyone
ever seen this before?
Of course, finite products (or coproducts) are essential;
otherwise one can easily construct single-object counterexamples. On
the other hand, Hilbert observes something similar but different in
an appendix to his book "Grundlagen der Geometrie": For unital rings,
the commutativity of addition follows from the other axioms; one can
even relax the exisence of the additive inverse to cancellation
conditions. The argument is as follows:
x+x+y+y=(1+1)x+(1+1)y=(1+1)(x+y)=1(x+y)+1(x+y)=x+y+x+y
Cancelling x on the left and y on the right, we get x+y=y+x.
Does anybody know more about similar implications?
Greetings
Reinhard
Date: Sat, 9 Dec 1995 14:19:18 -0400 (AST)
Subject: Re: associativity and commutativity of addition
Date: Wed, 3 Jan 1996 16:57:25 +0200
From: Pierre Ageron <ageron@matin.math.unicaen.fr>
A (At) 9:09 7/12/95, "categories"I ecrivait (wrote):
>Date: Thu, 7 Dec 1995 12:06:31 +0100
>From: BOERGER <Reinhard.Boerger@FernUni-Hagen.de>
>
>It is well-known that a category in which finite products exist and
>coincide with finite coproducts (i.e. a zero object exists and the
>binary product functor is naturally equivalent to the binary
>coproduct functor) is semi- additive, i.e. enriched over the monoidal
>closed category of commutative monoids. Conversely, in a semi-
>additive category, every (existing) finite product is automatically a
>finite coroduct in the canonical way (an vice versa). Now my student
>Claus Kirschner observed that the proof of the latter fact does not
>use associativity and commutativity of the addition. Strange enough,
>together with the first fact this means: If a category with finite
>products has an operation called "addition" with neutral element 0 on
>each hom-set satisfying f0=0f=0 and the distributive laws, then the
>addition is automatically associative and commutative. Has anyone
>ever seen this before?
> Of course, finite products (or coproducts) are essential;
>otherwise one can easily construct single-object counterexamples. On
>the other hand, Hilbert observes something similar but different in
>an appendix to his book "Grundlagen der Geometrie": For unital rings,
>the commutativity of addition follows from the other axioms; one can
>even relax the exisence of the additive inverse to cancellation
>conditions. The argument is as follows:
>x+x+y+y=(1+1)x+(1+1)y=(1+1)(x+y)=1(x+y)+1(x+y)=x+y+x+y
>Cancelling x on the left and y on the right, we get x+y=y+x.
>Does anybody know more about similar implications?
>
> Greetings
> Reinhard
This interesting remark illustrates a general algebraic phenomenon that
occurs when dealing with "unitary" theories or sketches. The most
well-known example is about internal groups in the category Gr of groups :
they are automatically
commutative (in the appropriate sense). Another example : internal "non
necessarily associative categories" in Gr are automatically associative.
On the other hand, an internal semigroup in the category Semigr of
semigroups need not be commutative; this is the reason why Semigr has many
multiplicative closed structures while Gr (or Mon, the category of monoids)
has none.
Unitary and non-unitary algebraic theories definitely have a very different
behaviour; this is one of the reasons why I think that the theory of
taxonomies (i.e. "categories without identities") should be taken more
seriously!
Pierre Ageron
Date: Sun, 10 Dec 1995 17:18:17 -0400 (AST)
Subject: Re: associativity and commutativity of addition
Date: Sat, 9 Dec 1995 17:21:25 -0500
From: Peter Freyd <pjf@saul.cis.upenn.edu>
I guess someone has to say it for the record. The question:
If a category with finite products has an operation called
"addition" with neutral element 0 on each hom-set satisfying f0=0f=0
and the distributive laws, then the addition is automatically
associative and commutative. Has anyone ever seen this before?
Yes, starting at least with Eckmann/Hilton in the 50's.
Date: Sun, 10 Dec 1995 17:19:05 -0400 (AST)
Subject: Dinatural exercise solved
Date: Sun, 10 Dec 1995 15:36:34 -0500
From: Peter Freyd <pjf@saul.cis.upenn.edu>
I had asked if the following is new:
Let *A* be a locally small category. Let *D* be the category
whose objects are set-valued bifunctors on *A* (contravariant on
the first variable, covariant on the second) and whose maps are the
dinatural transformations. Then *A* is a groupoid.
Meaning, of course, that dinaturals are closed under composition iff
*A* is a groupoid.
Well, all I've received are requests for the proof. So: given *A*
let P denote the covariant power-set functor on the category of
sets. Fix an object C. Consider the bifunctor that sends A to
P(C,A) and consider the dinatural transformation (A,A) -> P(C,A)
that sends an endomorphism e in (A,A) to the set of solutions o
the equation:
x x e
C -> A = C -> A -> A.
The composition 1 -> (A,A) -> P(C,A) has as its unique value the
_entire_ subset of maps from C to A. If it is dinatural then for
any f:A -> C:
P(C,A)
/
1 | P(1,f)
\
P(C,C).
g f
Every endomorphism of C is thus of the form C -> A -> C. In
particular, the identity map is of that form, that is, f is left
invertible, hence, every map targeted at C is left-invertible. If
this remains true for every C then every map in *A* is left
invertible, thus invertible.
I also asked for a reference for:
If *A* is a groupoid then *D* is equivalent to the category of
presheaves on *A*.
Nobody's asked for it, but let *A* be a groupoid anyway. For any
target category and any dinatural S -> T one may easily prove that
the hexagon used for defining dinaturals expands to a commutative
diagram (from which the computability of dinaturals easily follows):
SAA ------------------> TAA
SfA / \ SAf TfA / \ TAf
SBA SAB --> TBA TAB
SBf \ / SfB TBf \ / TfB
SBB -------------------> TBB.
If *A* is a groupoid then the category composed of dinaturals
between bifunctors from *A* to *B* is equivalent to the category
composed of natural transformations between covariant functors from
*A* to *B*.
Show that for any bifunctor, S, there is an isomorphism (in the
category composed of dinaturals) to a bifunctor, T, with the special
property that TAB = TAA and TAx = TA1. Given S define T to be
the bifunctor such that TAB = SAA and Tfg = Sff' (where f' is the
inverse of f). The collection of identity functions from SAA to
TAA forms a dinatural transformation as does the collection of
identity functions from TAA back to SAA.
The full subcategory of such functors is easily seen to be isomorphic
to the category of contravariant functors from *A* to *B*.
Date: Wed, 13 Dec 1995 09:59:19 -0400 (AST)
Subject: Discrete opfibrations of graphs
Date: Sun, 10 Dec 1995 19:52:30 +0100 (MET)
From: Sebastiano Vigna <vigna@colos3.usr.dsi.unimi.it>
Suppose you have coloured graphs G,H (with multiple edges,
etc. i.e., we are in the topos of coloured graphs). A morphism
G->H induces a functor between the free categories generated
by G and H. I am interested in those morphisms which induce
discrete opfibrations. Has anyone studied this notion?
Essentially, any arc f(x)->y of H can be lifted uniquely
to an arc (with the same label) x->x', for some x' such
that f(x')=y.
Sebastiano Vigna
Date: Wed, 13 Dec 1995 10:03:40 -0400 (AST)
Subject: Dinatural exercise solved: addendum
Date: Mon, 11 Dec 1995 09:13:51 -0500
From: Peter Freyd <pjf@saul.cis.upenn.edu>
Whoops. I lifted the proof I posted yesterday out of a longer ms I'm
writing. It occured to me (you know how it goes -- around 3 a.m.) that
it assumed the reader already knew the dinatural transformation
1 -> (A,A). Its source is the terminal set-valued bifunctor: the
constant bifunctor whose constant value is a one-element set. Its
target is the "hom" bifunctor. The dinatural transformation is the one
with identity maps as values.
See: the reader did already know it (because, of course, it's the
only dinatural from 1 to (A,A) that can be defined uniformly for
all categories).
Date: Thu, 14 Dec 1995 13:25:05 -0400 (AST)
Subject: position in Dunkerque
Date: Thu, 14 Dec 1995 11:33:38 --100
From: Enrico Vitale <vitale@lma.univ-littoral.fr>
Dear categorists,
a position of Maitre de Conferences (assistan-researcher) will be available
at the Universite du Littoral (Dunkerque-Calais, France) starting from the
next academic year.
We are particularly interested in applications of people working in category
theory and related areas.
A basic knowledge of French language and a Ph.D. degree are requested.
People interested in such a position should contact us as soon as possible
for more informations.
Best regards
Dominique Bourn Enrico Vitale
Enrico Vitale
Laboratoire LANGAL - Faculte de Sciences
Universite du Littoral
1 quai Freycinet - B.P. 5526
59379 Dunkerque - FRANCE
tel. 0033 - 28237161
fax 0033 - 28237039
e-mail vitale@lma.univ-littoral.fr
Date: Sat, 16 Dec 1995 16:41:49 -0400 (AST)
Subject: addresses for Max and Imogen Kelly
Date: Fri, 15 Dec 95 17:01:15 +1100
From: Max Kelly <kelly_m@maths.su.oz.au>
>From 17 Dec 1995 to 3 Feb 1996:
58 Crescent Road
Kingston-on-Thames
Surrey KT2 7RF
ENGLAND
Tel. +44-181-546-6383
email as usual kelly_m@maths.su.oz.au
>From 4 Feb to 29 Feb 1996:
C/o Prof. Aurelio Carboni,
Dipartimento di Matematica,
Universita' di Genova,
via Dodecaneso 35
16146 GENOVA,
ITALY.
(Phone Home 02-342935
Work 010-353-6804
Fax 010-353-6752
(Milan FAX: 39-2-70630346)
email for Kelly still as above.
Best wishes to all for the coming holiday season - Max and Imogen.
Date: Tue, 19 Dec 1995 20:57:13 -0400 (AST)
Subject: MSc course
Date: Tue, 19 Dec 1995 22:31:51 +0000 (GMT)
From: Edmund Robinson <E.P.Robinson@dcs.qmw.ac.uk>
Dear Colleagues,
Next year we shall be mounting a (heavily) revised version of our MSc
course, an advert for which follows. Please pass the advert on to
anyone you think might be interested. Please encourage all your best
students to apply to us. And of course, please have a wonderful
Christmas!
all best wishes
Edmund Robinson
PS Perhaps I should also take this opportunity to tell those of you
who haven't heard, that we are proud to announce the appointment of
Peter O'Hearn to a readership in the department. Peter continues a
departmental tradition of people called Peter with interests in
programming languages. He replaces Peter Landin, who has retired from
formal duties.
---------------------------------------------------
Queen Mary and Westfield College
University of London
Department of Computer Science
------------------------------------------------------
| Advanced MSc in Logic and Foundations of Programming |
------------------------------------------------------
Applications for entry in Autumn 1996 are invited from candidates who
have or expect to obtain a good honours degree in mathematics or a
subject with substantial mathematical content.
This newly designed MSc programme aims to allow mathematically able
students to acquire a thorough grounding in the logical foundations of
computer science and the theory and practice of programming.
----------
| Syllabus |
----------
Students take four courses:
* Programming
Programming in imperative, logic and functional languages;
specification and verification applied to imperative programs; the use
of equational specification; program transformation; logical
foundations of Prolog; partial evaluation.
* Deduction
Formal logical systems; structural proof theory including proof search
constructive logic and its semantics; type theory, lambda calculi and
structural operational semantics.
* Semantics
Universal algebra; category theory; categorical model theory; classical
denotational semantics; topics in modern denotational semantics.
* Concurrency
Game theory and its applications in logic and to the theory of processes;
process algebra; equivalences between processes; equational reasoning;
use of process calculus in specification and verification.
All four courses will be taught by active researchers who are experts
in these fields. Courses are taught over the first two semesters, with
the remainder of the year being devoted to the project.
---------
| Funding |
---------
We expect that a small number of EPSRC studentships will be available
for suitably qualified candidates.
---------------------
| Further information |
---------------------
Prof E.P. Robinson (edmundr@dcs.qmw.ac.uk)
or
Dr D.J. Pym (pym@dcs.qmw.ac.uk)
Department of Computer Science, Tel: +44 (0)171 975 5555
Queen Mary and Westfield College, Fax: +44 (0)181 980 6533
University of London, URL: http://www.dcs.qmw.ac.uk/
Mile End Road,
London E1 4NS,
England, U.K.
Date: Thu, 21 Dec 1995 10:14:23 -0400 (AST)
Subject: 3rd WoLLIC'96 - 2nd Call
Date: Thu, 21 Dec 95 09:20:54 EST
From: Ruy de Queiroz <ruy@di.ufpe.br>
Second Call for Contributions
3rd Workshop on Logic, Language, Information and Computation
(WoLLIC'96)
May 8-10, 1996
Salvador (Bahia), Brazil
The `3rd Workshop on Logic, Language, Information and Computation' (WoLLIC'96)
will be held in Salvador, Bahia (Brazil), from the 8th to the 10th May 1996.
Contributions are invited in the form of two-page (600 words) abstract in all
areas related to logic, language, information and computation, including: pure
logical systems, proof theory, model theory, type theory, category theory,
constructive mathematics, lambda and combinatorial calculi, program logic and
program semantics, nonclassical logics, nonmonotonic logic, logic and language,
discourse representation, logic and artificial intelligence, automated
deduction, foundations of logic programming, logic and computation, and logic
engineering.
There will be a number of guest speakers, including:
Andreas Blass (Ann Arbor), Nachum Dershowitz (Urbana-Champaign),
Keith Devlin (St. Mary's), J. Michael Dunn (Indiana),
Peter G"ardenfors (Lund), Jeroen Groenendijk (Amsterdam),
Wilfrid Hodges (London), Roger Maddux (Ames, Iowa),
Andrew Pitts (Cambridge), Amir Pnueli (Rehovot),
Michael Smyth (London).
WoLLIC'96 is part of a larger biennial event in computer science being held in
the campus of the Federal University of Bahia from the 6th to the 10th of May
1996: the `6th SEMINFO' (6th Informatics Week). The 6th SEMINFO will involve
parallel sessions, tutorials, mini-courses, as well as the XI Brazilian
Conference on Mathematical Logic (EBL'96), and a Workshop on Distributed
Systems (WoSiD'96).
Submission:
Two-page abstracts, preferably by e-mail to *** wollic96@di.ufpe.br *** must be
RECEIVED by MARCH 8th, 1996 by the Chair of the Organising Committee. Authors
will be notified of acceptance by April 8th, 1996. The 3rd WoLLIC'96 is under
the official auspices of the Interest Group in Pure and Applied Logics (IGPL)
and The European Association for Logic, Language and Information (FoLLI).
Abstracts will be published in the Journal of the IGPL (ISSN 0945-9103) as part
of the meeting report. Selected contributed papers will be invited for
submission (in full version) to a special issue of the Journal.
The location:
Salvador, Capital of the Bahia state, the first European settlement of
Portuguese America and the first Capital of Brazil, is where all the most
important colonial buildings were constructed: churches, convents, palaces,
forts and many other monuments. Part of the city historical center has been
safekept by UNESCO since 1985. Five hundred years of blending Native American,
Portuguese, and African influences have left a rich culture to its people, which
can be felt on its music, food, and mysticism. Salvador is located on the
northeastern coast of Brazil and the sun shines year round with the average
temperature of 25 degrees Celsius. It is surrounded by palm trees and beaches
with warm water. City population is around 2.5 million and life style is quite
relaxed.
Programme Committee:
W. A. Carnielli (UNICAMP, Campinas), M. Costa (EMBRAPA, Brasilia),
V. de Paiva (Cambridge Univ., UK), R. de Queiroz (UFPE, Recife),
A. Haeberer (PUC, Rio), T. Pequeno (UFC, Fortaleza), L. C. Pereira (PUC, Rio),
K. Segerberg (Uppsala Univ., Sweden), A. M. Sette (UNICAMP, Campinas),
P. Veloso (PUC, Rio).
Organising Committee:
H. Benatti (UFPE), L. S. Baptista (UFPE), A. Duran (UFBA), T. Monteiro (UFPE),
A. G. de Oliveira (UFBA), N. Riccio (UFBA).
For further information, contact the Chair of Organising Committee:
R. de Queiroz, Departamento de Informatica, Universidade Federal de Pernambuco
(UFPE) em Recife, Caixa Postal 7851, Recife, PE 50732-970, Brazil,
e-mail: ruy@di.ufpe.br, tel.: +55 81 271 8430, fax: +55 81 271 8438.
(Co-Chair: T. Pequeno, LIA, UFC, tarcisio@lia.ufc.br, fax +55 85 288 9845)
Web homepage: http://www.di.ufpe.br/simposios/wollic.html
-----
\documentstyle[a4]{article}
\renewcommand{\thepage}{}
\begin{document}
\begin{center}
{\large\bf 3rd Workshop on Logic, Language, Information and Computation
(WoLLIC'96)}\\[1.0ex]
{\large May 8--10, 1996}\\[.8ex]
{\large Salvador (Bahia), Brazil}\\[1.0ex]
\end{center}
\bigskip
\noindent
The {\bf 3rd Workshop on Logic, Language, Information and Computation}
({\bf WoLLIC'96}) will be held in Salvador, Bahia (Brazil), from the 8th to the
10th May 1996. Contributions are invited in the form of two-page (600 words)
abstract in all areas related to logic, language, information and computation,
including: pure logical systems, proof theory, model theory, type theory,
category theory, constructive mathematics, lambda and combinatorial calculi,
program logic and program semantics, nonclassical logics, nonmonotonic logic,
logic and language, discourse representation, logic and artificial intelligence,
automated deduction, foundations of logic programming, logic and computation,
and logic engineering.\\
There will be a number of guest speakers, including:\\
Andreas Blass (Ann Arbor), Nachum Dershowitz (Urbana-Champaign),
Keith Devlin (St.\ Mary's), J.\ Michael Dunn (Indiana),
Peter G\"ardenfors (Lund), Jeroen Groenendijk (Amsterdam),
Wilfrid Hodges (London), Roger Maddux (Ames, Iowa),
Andrew Pitts (Cambridge), Amir Pnueli (Rehovot), Michael Smyth (London)\\
{\bf WoLLIC'96} is part of a larger biennial event in computer
science being held in the campus of the Federal University of Bahia from the
6th to the 10th of May 1996: the {\bf 6th SEMINFO} (6th Informatics Week). The
{\bf 6th SEMINFO} will involve parallel sessions, tutorials, mini-courses, as
well as the {\bf XI Brazilian Conference on Mathematical Logic} ({\bf EBL'96}),
and a {\bf Workshop on Distributed Systems} ({\bf WoSiD'96}).\\
{\bf Submission}:
Two-page abstracts, preferably by e-mail to ***~wollic96@di.ufpe.br~*** must be
RECEIVED by MARCH 8th, 1996 by the Chair of the Organising Committee. Authors
will be notified of acceptance by April 8th, 1996. The {\bf 3rd WoLLIC'96} is
officially sponsored by the Interest Group in Pure and Applied Logics (IGPL) and
The European Association for Logic, Language and Information (FoLLI).
The {\bf EBL'96} is the annual meeting of Brazilian Logic Society.
Abstracts will
be published in the Journal of the IGPL (ISSN 0945-9103) as part of the meeting
report. Selected contributed papers will be invited for submission (in full
version) to a special issue of the Journal.\\
{\bf The location}:
Salvador, Capital of the Bahia state, the first European settlement of
Portuguese America and the first Capital of Brazil, is where all the most
important colonial buildings were constructed: churches, convents, palaces,
forts and many other monuments. Part of the city historical center has been
safekept by UNESCO since 1985. Five hundred years of blending Native American,
Portuguese, and African influences have left a rich culture to its people, which
can be felt on its music, food, and mysticism. Salvador is located on the
northeastern coast of Brazil and the sun shines year round with the average
temperature of 25 degrees Celsius. It is surrounded by palm trees and beaches
with warm water. City population is around 2.5 million and life style is quite
relaxed.\\
{\bf Programme Committee}:
W.\ A.\ Carnielli (UNICAMP, Campinas), M.\ Costa (EMBRAPA, Brasilia),
V.\ de Paiva (Cambridge Univ., UK), R.\ de Queiroz (UFPE, Recife),
A.\ Haeberer (PUC, Rio), T.\ Pequeno (UFC, Fortaleza),
L.\ C.\ Pereira (PUC, Rio), K.\ Segerberg (Uppsala Univ., Sweden),
A.\ M.\ Sette (UNICAMP, Campinas), P.\ Veloso (PUC, Rio).\\
{\bf Organising Committee}:
H.\ Benatti (UFPE), L.\ S.\ Baptista (UFPE), A.\ Duran (UFBA),
T.\ Monteiro (UFPE), A.\ G.\ de Oliveira (UFBA), N.\ Riccio (UFBA).\\
For further information, contact the Chair of Organising Committee:
R.\ de Queiroz, Departamento de Inform\'atica, Universidade Federal de
Pernambuco (UFPE) em Recife, Caixa Postal 7851, Recife, PE 50732-970, Brazil,
e-mail: ruy@di.ufpe.br, tel: +55~81~271~8430, fax +55~81~271~8438.
(Co-Chair: T.\ Pequeno, LIA, UFC, tarcisio@lia1.ufc.br, fax +55~85~288~9845)\\
Web homepage: http://www.di.ufpe.br/simposios/wollic.html
\end{document}
Date: Thu, 21 Dec 1995 10:13:00 -0400 (AST)
Subject: (Fwd) Re: Abstracts "Descent Theory", Oberwolfach '95
Date: Wed, 20 Dec 1995 13:51:34 -0500
From: Walter Tholen <tholen@mathstat.yorku.ca>
Subject: (Fwd) Re: Abstracts "Descent Theory", Oberwolfach '95
Dear Colleagues,
a link has been appended to my WWW home page to obtain the notes of Ross
Street's lectures on Descent Theory at the Oberwolfach Conference in September.
These files may accessed also directly; the address is
ftp://ftp.mpce.mq.edu.au/pub/maths/Categories/Oberwolfach/
The files themselves are:
-rw-r--r-- 1 ross ftpmaths 1329104 Dec 13 16:34 Oberwolfach_1.ps
-rw-r--r-- 1 ross ftpmaths 707855 Dec 13 16:33 Oberwolfach_1.ps.Z
-rw-r--r-- 1 ross ftpmaths 1196252 Dec 13 16:34 Oberwolfach_2.ps
-rw-r--r-- 1 ross ftpmaths 605741 Dec 13 16:34 Oberwolfach_2.ps.Z
-rw-r--r-- 1 ross ftpmaths 1018897 Dec 13 16:37 Oberwolfach_3.ps
-rw-r--r-- 1 ross ftpmaths 549743 Dec 13 16:37 Oberwolfach_3.ps.Z
... giving a PostScript file (txt) and a compressed (binary) version
of each.
A good Web browser can get them using the above as a URL.
It may even automatically uncompress and render the PostScript file.
Best wishes for the Holiday Season and a Happy New Year!
Walter.
--
Walter Tholen
Department of Mathematics and Statistics
York University, North York, Ont., Canada M3J 1P3
tel. (416) 736 5250 or 736 2100, ext. 33918
fax. (416) 736 5757
http://www.math.yorku.ca/Who/Faculty/Tholen/menu.html
Date: Sun, 24 Dec 1995 11:44:33 -0400 (AST)
Subject: Query about citations
Date: Fri, 22 Dec 1995 16:49:27 -0800
From: David B. Benson <dbenson@eecs.wsu.edu>
One defines the category of Diagrams on category A, Diag(A), as
in Makkai & Pare's "Accessible Categories". One similarly defines
the category of cones on diagrams on A and the category of
cocones on diagrams on A. Limits and colimits exist when
certain adjunctions hold between these derived categories.
I am sure I have seen one or more papers or monographs giving
the details for the above. I simply cannot recall where this (these)
workout(s) appeared. I would like to (re)read the paper(s), so
I would greatly appreciate receiving reminders about where
to look for these results.
Thank you in advance.
With the warmest of season's greetings,
David
Date: Fri, 29 Dec 1995 10:22:34 -0400 (AST)
Subject: Re: Query about citations
Date: Fri, 29 Dec 1995 13:09:38 GMT
From: Max Kelly <kelly_m@dcs.qmw.ac.uk>
In answer to David Benson's question of 22 Dec, a BETTER way of looking
at the whole matter, which works even for weighted limits, is explained
in
Albert, H.M. and Kelly, G.M., The closure of a class of colimits,
JPAA 51 (1988) 1--17
Regards, Max Kelly.