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Sjouke Mauw | 1 Jun 1999 14:19
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CONCUR'99 Call for participation

                          CALL FOR PARTICIPATION
                                  and
                              FINAL PROGRAM

                               CONCUR'99
          10th International Conference on Concurrency Theory
            Eindhoven, The Netherlands, August 24--27, 1999.

                   URL http://www.win.tue.nl/concur99/
                         E-mail concur99 <at> win.tue.nl

(apologies for multiple copies)

REGISTRATION
It is now time to register for CONCUR'99. See the above mentioned WWW
pages for the registration procedure.
Early registration ends on July 1, 1999.

CONCUR
The purpose of the CONCUR conferences is to bring together researchers,
developers and students in order to advance the theory of concurrency,
and promote its applications.

PROGRAM

Monday August 23
================

CONCUR'99 Satellites:
 Probmiv'99
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Jiri Adamek | 2 Jun 1999 15:53
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JPAA issue in honor of S.Mac Lane


PROCEDINGS OF THE CATEGORY THEORY CONFERENCE IN COIMBRA (JULY 1999)

A special issue of the Journal of Pure and Applied Algebra, dedicated to
the ninetieth birthday of Saunders Mac Lane, is planned to contain the 
proceedings of the Coimbra meeting. Due to space limitations, only
contributions closely related to lectures presented at the conference
will be accepted. The submission deadline is November 30, 1999, and
more detailed instructions about submissions will be announced during
the conference.

J. Adamek, P. Johnstone, and M. Sobral
editors of the special issue
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Michael Barr | 2 Jun 1999 22:53

My ftp directory

Some of you have been trying unsuccessfully to get files from my ftp
directory, which mysteriously disappeared.  It is now restored.  The
address is ftp.math.mcgill.ca/pub/barr.

Michael

-------------------------------------------------------------------
If a society puts up with bad plumbers because plumbing is such a low
calling, and if it puts up with bad philosophers because philosophy is
such a high calling---then neither its pipes nor its theories will hold
water.  --- Slight paraphrase of former HEW secretary John Gardner
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Jose Nuno Oliveira | 2 Jun 1999 18:02
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MPC2000: 5th Int. Conf. on Math. of Program Construction - CFP


                                MPC 2000

                     5th International Conference on

                   MATHEMATICS OF PROGRAM CONSTRUCTION
                   -----------------------------------

                     http://www.di.uminho.pt/mpc2000

                             3--7 July, 2000

                         Ponte de Lima, Portugal

                             CALL FOR PAPERS

This conference aims to promote the development of mathematical principles
and techniques that are demonstrably useful and usable in the process of
constructing computer programs (whether implemented in hardware or software).
The focus of the conference is on techniques that combine precision with
concision, enabling programs to be constructed by formal calculation.
Within this theme, the scope of the conference is very diverse.
We welcome contributions to  programming methodology (for example, formal
methods for program specification and  transformation), to programming
paradigms (for example, generic programming techniques and type systems)
and to language design (for example, programming calculi and programming
language semantics).  Theoretical contributions are welcome provided their
relevance to program construction is evident; discussion of applications is
welcome provided the mathematical basis is evident.
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Eva Ullan | 4 Jun 1999 21:44
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CSL'99 Call for Participation

	-------------------------------------------------------------
	 CALL FOR REGISTRATION AND PARTICIPATION
                                                 CSL'99

	 Annual Conference of the European Association
	             for Computer Science Logic (EACSL)

	      Madrid, Spain, September 20-25, 1999
	-------------------------------------------------------------

***************************************************
INVITED LECTURERS
TUTORIALS
CONTRIBUTED PAPERS
GENERAL INFORMATION
REGISTRATION AND ACCOMODATION
***************************************************

Sponsored by:
Departamento Sistemas Informaticos y Programacion (SIP) - UCM
European Research Consortium for Informatics and Mathematics - ERCIM
Esprit Working Group - CCLII
 Facultad de Matematicas - UCM
Ministerio de Educacion y Ciencia - CICYT
Viverrectorado de Investigacion - UCM
Viverrectorado de Relaciones Internacionales - UCM

Organised by:
SIP-UCM
DACYA-UCM
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Charles Wells | 8 Jun 1999 16:37

CTCS '93?

While updating the bibliography for the third edition of Barr & Wells,
Category Theory for Computing Science, I discovered that I had no record of
a Category Theory and Computer Science conference for 1993, although they
are supposed to be held biennially and were held in 1989, 1991, 1995 and
1997.  This may only mean that no library in Ohio has a copy of the
proceedings.  Any information on this would be appreciated.

Charles Wells, Department of Mathematics, Case Western Reserve University,
10900 Euclid Ave., Cleveland, OH 44106-7058, USA.
EMAIL: charles <at> freude.com. OFFICE PHONE: 216 368 2893.
FAX: 216 368 5163.  HOME PHONE: 440 774 1926.  
HOME PAGE: URL http://www.cwru.edu/artsci/math/wells/home.html
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Colin McLarty | 12 Jun 1999 19:42
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"Universes" within ZFC

        The following improves on remarks I made to some people at the
recent Buffalo meeting, and on the FOM e-mail list.

   	This is a step towards showing Grothendieck's method of universes for
algebraic geometry can be formalized nearly unchanged in ZFC, without the
further axiom asserting existence of Grothendieck universes. To any set of
sites (or ringed sites) we associate a "generating cardinal" k and consider
as universes the sets V(i) where i is a limit ordinal larger than k and k
not cofinal in i. ZFC proves every set is a member of such a "universe".
These universes are at least models of Zermelo set theory plus countable
replacement. So, for example, for any set S and finitary operation on S in
the universe, the closure of S under that operation is also in the universe.
This obviously suffices for most of Grothendieck's theorems in TOHOKU and
SGA. The only theorem that stands out as needing more is existence of
injectives in AB5 categories with generators. I will show these universes
suffice for that theorem, for the AB5 categories associated to those
(ringed) sites. The problem is simply to find bounds on the transfinite
inductions we use. But these are not as simple as I had thought.    

        For any site C we can construct a generator U for the category of
Abelian sheaves on C, which works no matter which universe of sets we use to
define the topos on C (assuming, of course, that C is in the universe). Any
of the standard constructions have this property. And U has a fixed poset of
subsheaves (up to equivalence as monics to U) also independent of the
universe of sets. The "generating cardinal" for C is the first infinite
cardinal greater than the number of subobjects of U. Actually we can make it
smaller by a slightly more complicated definition: We can take the first
infinite cardinal greater than the length of  any chain of subobjects of U
well ordered by inclusion.
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Michael Barr | 12 Jun 1999 15:04

Question on subobject classifiers

I am reviewing a paper whose main result sounds like it ought to be known.
Is it and can anyone give me a citation?

Let E be a cocomplete category with a small dense subcategory C (so every
e of E is the colimit of C/e --> E).  Then an object \Omega of E is a
subobject classifier in E iff it represents the subobject functor
restricted to C.

-------------------------------------------------------------------
If a society puts up with bad plumbers because plumbing is such a low
calling, and if it puts up with bad philosophers because philosophy is
such a high calling---then neither its pipes nor its theories will hold
water.  --- Slight paraphrase of former HEW secretary John Gardner
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I. Moerdijk | 16 Jun 1999 15:51
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Preprint: I. Moerdijk: "On the Connes-Kreimer construction of Hopf algebras"

I. Moerdijk: "On the Connes-Kreimer construction of Hopf algebras"

Abstract: We give a universal construction of families of Hopf P-algebras
for any Hopf operad P. As a special case, we recover the Connes-Kreimer
Hopf algebra of rooted trees. 

Available from http://www.math.uu.nl/people/moerdijk/preprints.html.
---------------------------------------
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Vaughan Pratt | 17 Jun 1999 07:24
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Dinaturality in the CCC Poset

The cartesian closed category Pos of posets comes with functors built
using x and ->.  Are there any spurious dinatural transformations between
these functors, in the sense that they cannot be represented in a suitable
simply-typed lambda-calculus?

While the general question is for n-ary functors, the case of unary
functors like Ax(A->A) -> AxAxA should constitute the nub of the problem.

Bob Pare mentioned to me at CT97 in Vancouver that A->A in Pos was "clean"
in this sense, having only the expected dinaturals from A->A to A->A,
namely the Church numerals.  This is in contrast to Set, where Pare and
Roman in a JPAA paper last year (pp. 33-92) gave a litany of spurious
dinaturals for this functor, and also to Chu(Set,2), which likewise
has spurious dinaturals from A-oA to A-oA, albeit of a quite different
character from those of Set.

The only closed monoidal category I'm aware of that contains no spurious
dinaturals in this sense is Girard's *-autonomous category Coh of
coherence spaces, for which Audrey Tan obtained full completeness
for multiplicative linear logic in her 1997 Ph.D. thesis.  That is,
the only dinaturals between functors built using tensor product and -o
are those corresponding to cut-free MLL proofs, the MLL criterion for
"no spurious dinaturals."

What other monoidal closed categories arise in nature that have no
spurious dinaturals?  Are any of them cartesian closed?  In particular
is Pos such?  And how about PER?

Vaughan Pratt
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Gmane