Jiri Adamek | 6 Nov 14:39 2006

reflexive coequalizers

The indiscrete-category functor I: Set -> Cat is not algebraically
exact as I claimed in my posting of October 9. But I is
a full codomain restriction of one: as in that posting, let F
be the forgetful functor the Gabriel-Ulmer theory T
of categories to the theory of sets. Then Alg F is an algebraically
exact functor from Set to Alg T, and the Yoneda embedding
Y: Cat -> Alg T is fully faithful (since the dual of T is dense in Cat).
It is easy to see that Alg F is naturally isomorphic to Y.I , thus,
I preserves sifted colimits.

alternative e-mail address (in case reply key does not work):
J.Adamek <at> tu-bs.de


CfP: Special issue I&C on SOS

                           Call for Papers:

                            Special Issue
                      Information & Computation
                   Structural Operational Semantics

Aim: Structural operational semantics (SOS) provides a framework
for giving operational semantics to programming and specification
languages. A growing number of programming languages from
commercial and academic spheres have been given usable semantic
descriptions by means of structural operational semantics. Because
of its intuitive appeal and flexibility, structural operational
semantics has found considerable application in the study of the
semantics of concurrent processes. Moreover, it is becoming a
viable alternative to denotational semantics in the static analysis
of programs, and in proving compiler correctness.

Recently, structural operational semantics has been successfully
applied as a formal tool to establish results that hold for classes
of process description languages. This has allowed for the
generalisation of well-known results in the field of process
algebra, and for the development of a meta-theory for process
calculi based on the realization that many of the results in this
field only depend upon general semantic properties of language

This special issue aims at documenting state-of-the-art research, new
(Continue reading)

Ross Street | 12 Nov 03:48 2006

Morgan-Phoa Mathematics Workshop

Anyone interested in category theory and related topics who can be in
Canberra (Australia) at the end of November is welcome to join in the

	Morgan-Phoa Mathematics Workshop

to be held at the Australian National University.

I have set up a little Web page which I will update as the event


Till Mossakowski | 16 Nov 11:28 2006

9 research assistant positions available

9 research assistant positions (most of them TVL 13,
approx. € 35,000 to € 50,000 p.a. gross) available, at

Transregional Collaborative Research Center SFB/TR 8 Spatial Cognition:
Reasoning, Action, Interaction
at the Universities of Bremen and Freiburg, Germany	

The positions are in general concerned with interdisciplinary
long-term research in Spatial Cognition.

Some of the positions may be of interest to the readers of this list,
because formal methods, logic and category theory are used.

For details, see
(in particular, projects I1, I3 and I4)


Till Mossakowski    Office:      Phone +49-421-218-64226
DFKI Lab Bremen     Cartesium    Fax +49-421-218-9864226
Robert-Hooke-Str. 5 Enrique-Schmidt-Str. 5   till <at> tzi.de
D-28359 Bremen      Room 2.051   http://www.tzi.de/~till

jim stasheff | 21 Nov 14:55 2006

Re: NUMDAM progress

     *  archive: http://listserv.albany.edu:8080/archives/emj.html  *

Wow! yes, especially the Seminaire H Cartan


Larry Siebenmann wrote:
>      ****************************************************************
>      *  archive: http://listserv.albany.edu:8080/archives/emj.html  *
>      ****************************************************************
> *** NUMDAM progress
> Dear Friends,
>      Digitization continues, particularly in Europe.
> You will find much good mathematics not easily accessible
> otherwise at :
>       http://archive.numdam.org/numdam-bin/browse
> Here is the impressive list of Journals etc. now scanned.
> I was particularly pleased to find the Cartan Seminar
> and numerous cousins.
(Continue reading)

Todd Wilson | 27 Nov 07:16 2006

Implicit algebraic operations

I was going through some of my old notes today and came across
investigations I had done several years ago on implicit operations in
Universal Algebra.  These are definable partial operations on algebras
that are preserved by all homomorphisms.  Here are two examples:

(1) Pseudocomplements in distributive lattices.  Given a <= b <= c in a
distributive lattice, there is at most one b' such that

     b /\ b' = a   and   b \/ b' = c.

Because lattice homomorphisms preserve these inequalities and equations,
the uniqueness of pseudocomplements implies that, when they exist, they
are also preserved by homomorphisms.

(2) Multiplicative inverses in monoids.  Similarly, given an element m
in a monoid (M, *, 1), there is at most one element m' such that

     m * m' = 1    and    m' * m = 1.

It follows that inverses, when they exist, are also preserved by monoid

Now, the investigation of these partial operations gets one quickly into
non-surjective epimorphisms, dominions in the sense of Isbell, algebraic
elements in the sense of Bacsich, implicit partial operations in the
sense of Hebert, and other topics.  Some of the references that I know
about are listed below.

My question is this:  Does a definitive treatment of this phenomenon in
"algebraic" categories exist?  Are there still some mysteries/open problems?
(Continue reading)

Phil Scott | 27 Nov 03:33 2006

CFP: Symposium on Logical Foundations of Computer Science LFCS07

Revised Call for papers
New York City, June 4 - 7, 2007
URL: www.cs.gc.cuny.edu/lfcs07
Email: lfcs07 <at> gmail.com
* Purpose. The LFCS series provides an outlet for the fast-growing body of
work in the logical foundations of computer science, e.g., areas of
fundamental theoretical logic related to computer science. The LFCS schedule
is consistent with LICS and CSL timelines.
* Theme. Constructive mathematics and type theory; logical foundations of
programming; logical aspects of computational complexity; logic programming
and constraints; automated deduction and interactive theorem proving; logical
methods in protocol and program verification; logical methods in program
specification and extraction; domain theory logics; logical foundations of
database theory; equational logic and term rewriting; lambda and combinatory
calculi; categorical logic and topological semantics; linear logic; epistemic
and temporal logics; intelligent and multiple agent system logics; logics of
proof and justification; non-monotonic reasoning; logic in game theory and
social software; logic of hybrid systems; distributed system logics; system
design logics; other logics in computer science.
* All submissions must be done electronically (15 pages, pdf, 12pt) via
* Submission deadline: December 11, 2006
* Notification: January 11, 2007
* Steering Committee. Anil Nerode (Cornell, General Chair); Stephen Cook
(Toronto); Dirk van Dalen (Utrecht); Yuri Matiyasevich (St.Petersburg); John
McCarthy (Stanford); J. Alan Robinson (Syracuse); Gerald Sacks (Harvard); Dana
Scott (Carnegie-Mellon).
(Continue reading)

mhebert | 27 Nov 16:48 2006

Re: Implicit algebraic operations

Hi everyone,

Todd Wilson asks :
> My question is this: Does a definitive treatment of this phenomenon [pa=
rtial operations
, ...,  non-surjective epimorphisms,...] in
> "algebraic" categories exist? Are there still some mysteries/open probl=

It seems to me that the problem of
"characterizing the algebraic theories giving rise to varieties where all=
 the epis are surjective"
(posed by Bill Lawvere in
Some algebraic problems in the context..., LNM 61 (1968) )
is still essentially open. Anyone knows otherwise?
(A "classical" version might be to find a - syntactic-  condition on the =
equations necessary and sufficient to have all epis surjective in its cat=
egory of its models)

Michel Hebert

Fromcat-dist <at> mta.ca

Tocategories <at> mta.ca


DateSun, 26 Nov 2006 22:16:59 -0800

Subjectcategories: Implicit algebraic operations
(Continue reading)

Andrei Sabelfeld | 28 Nov 11:44 2006

IEEE Computer Security Foundations 2007 - call for papers

Attachment: application/octet-stream, 6709 bytes
Jiri Adamek | 29 Nov 15:58 2006

A question about extensive categories

Dear colleagues,

Does anyone know whether every extensive and locally finitely presentable
category fulfils the following condition:

For every omega op-chain of coproduct injections i_n: A_n+1 -> A_n
with all A_n finitely presentable some i_n is an isomorphism.

We need this for investigating iterative monads in such categories,
and we have not managed to prove it, nor to find a counterexample.

Jiri Adamek, Stefan Milius and Jiri Velebil

alternative e-mail address (in case reply key does not work):
J.Adamek <at> tu-bs.de