March 2002 - Categories - categories.org.au

Only two SMC structures on Cat?
by Jason C Reed 27 Jul '02

27 Jul '02

Power, A.J. and Robinson, E.P. Premonoidal categories and notions of computation (ftp://ftp.dcs.qmw.ac.uk/pub/lfp/edmundr/premoncat.ps.gz) in section 2 asserts that there is excatly one symmetric monoidal closed structure on Cat besides the cartesian one. Does anyone know [the location of] a proof? ---Jason

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CTCS-Final CFP and deadline extension
by blute＠iml.univ-mrs.fr 02 Apr '02

02 Apr '02

Please note that we have extended the deadline by 4 days. cheers, Rick Blute Program Committee Chair +++++++++++++++++++++++++++++++++++ CATEGORY THEORY AND COMPUTER SCIENCE (CTCS'02) AUGUST 15-17, 2002 GRADUATE STUDENT PRECONFERENCE AUGUST 12-14, 2002 University of Ottawa Ottawa, Ontario, Canada FINAL CALL FOR PAPERS CTCS '02 is the 9th Conference on Category Theory and Computer Science. The purpose of the conference series is the advancement of the foundations of computing using the tools of category theory. The emphasis is upon applications of category theory, but it is recognized that the area is highly interdisciplinary. Typical topics of interest include, but are not limited to, category-theoretic aspects of the following: coalgebras and computing concurrent and distributed systems constructive mathematics declarative programming and term rewriting domain theory and topology foundations of computer security linear logic modal and temporal logics models of computation program logics, data refinement, and specification programming language semantics type theory Previous meetings have been held in Guildford (Surrey), Edinburgh (twice), Manchester, Paris, Amsterdam, Cambridge, and S. Margherita Ligure (Genova). This is the first time CTCS will be held in North America. The proceedings of the conference will be published as a special issue of ENTCS (Electronic Notes in Theoretical Computer Science). Paper copies of the proceedings will be available to participants at the conference. GRADUATE STUDENT PRECONFERENCE One new feature that CTCS will have this year is a "preconference" from August 12-14. The goal is to prepare students for CTCS, through mini-courses in the basic areas underlying the fields of the conference. We anticipate offering courses in the following areas: Introduction to Category Theory Introduction to Categorical Logic Coalgebras Communication and Concurrency Game Semantics Linear Logic PROGRAMME COMMITTEE Rick Blute, Chair (Ottawa) Robin Cockett (Calgary) Thierry Coquand (Chalmers) Andrea Corradini (Pisa) Thomas Ehrhard (Luminy) Ryu Hasegawa (Tokyo) Martin Hofmann (Munich) Bart Jacobs (Nijmegen) Michael Johnson (Macquarie) Dusko Pavlovic (Kestrel Institute) Alex Simpson (Edinburgh) ORGANIZING COMMITTEE E. Moggi, Chair, (Genova) S. Abramsky (Oxford) P. Dybjer (Chalmers) B. Jay (Sydney) A. Pitts (Cambridge) LOCAL ORGANIZING COMMITTEE R. Blute (Ottawa) P. Scott (Ottawa) SUBMISSION OF PAPERS Papers should be submitted, preferably in electronic form, to ctcs02(a)mathstat.uottawa.ca. Papers are limited to 15 pages, and must be submitted in dvi, postscript, or pdf format, possibly gzipped and/or uuencoded, or sent as a standard email attachment. All submissions must be received by March 25th, 2002. If you cannot submit your paper electronically, please contact the program chair at ctcs02(a)mathstat.uottawa.ca. IMPORTANT DATES March 29th, 2002 Submission deadline May 20th, 2002 Notification of authors of accepted papers CONFERENCE HOMEPAGE Updated information is available from http://www.mathstat.uottawa.ca/lfc/ctcs2002/. 25-Mar-2002 22:03:49 -0400,1006;000000000000-00000000

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None
by cat-dist＠mta.ca 30 Mar '02

30 Mar '02

=09by mailserv.mta.ca with smtp (Exim 3.33 #2) =09id 16qtgS-0005CP-00 =09for categories(a)mta.ca; Fri, 29 Mar 2002 06:32:36 -0400 2 -0400 =09 by emily.cs.bham.ac.uk (Exim 3.11 #1) with esmtp id 16qteg-0001ER-00 ;= Fri, 29 Mar 2002 10:30:46 +0000 Date: Fri, 29 Mar 2002 10:31:58 GMT From: Marta Z Kwiatkowska <M.Z.Kwiatkowska(a)cs.bham.ac.uk> Message-Id: <200203291031.g2TAVwi02164(a)preston.cs.bham.ac.uk> To: categories(a)mta.ca Subject: categories: jobs: Lectureships at the University of Birmingham Sender: cat-dist(a)mta.ca Precedence: bulk Three academic posts, School of Computer Science, University of Birmingham -------------------------------------------------------------------------- Applications are invited for three open-ended appointments, at the level of= Lecturer or Senior Lecturer, in Computer Science, Software Engineering or = Artificial Intelligence. One post is available to start from 1 September 20= 02 (or later), the remaining two will be available from 01 January 2003 (or= later): exact start dates are negotiable.=20 The appointees will be expected to contribute stongly to research, teaching= and administration within the School. We would welcome applicants who wish= to lead the School into new research or teaching areas as well as those wh= o wish to add to the School's existing strengths. The School also encourage= s industrial collaboration and consultancy.=20 The School obtained a grade of 5 in the 2001 national Research Assessment E= xercise. This shows international recognition of the excellence of the Scho= ol's research. The School is now starting a new phase of expansion over sev= eral years which is planned to include the appointment of a new professor (= equivalent to full professor in the USA).=20 Applicants should have an internationally excellent research background in = Computer Science, Software Engineering or Artificial Intelligence, as evide= nced by publications in leading international journals or conference procee= dings in these fields. Applicants should have teaching experience in one of= the fields, and should have, or expect soon to have, a PhD in one of the f= ields or an appropriate, closely related discipline.=20 Applicants for a Senior Lecturership should already meet our criteria for p= romotion to that level. For these criteria, please contact Mr David King, t= el: (+44)(0)121 414 3711; email: D.J.King(a)cs.bham.ac.uk.=20 Starting salary for Lecturers on scale =A320,470 - =A332,537 a year dependi= ng on experience and qualifications. Starting salary for Senior Lecturers o= n scale =A334,158 - =A338,603 year depending on experience and qualificatio= ns.=20 Informal enquiries to Professor Aaron Sloman on tel: (+44) (0)121 414 3711 = or email: A.Sloman(a)cs.bham.ac.uk=20 Please state in any application whether you are interested in a Lectureship= or Senior Lectureship. Application forms returnable by 25 April 2002 (late= applications may be considered). Further particulars can be found at: http= ://www.cs.bham.ac.uk/news/jobs/Lectureship2002.html Please quote reference = S35803/02.=20 Working towards equal opportunities.=20

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Finite limits by pullbacks and terminal object
by Till Mossakowski 28 Mar '02

28 Mar '02

The well-known theorem that finite limits can be obtained via finite products and equalizers has as a corollary that finite limits can also be obtained via pullbacks and a terminal object. This also yields a decomposition of any limiting cone over some finite diagram into pullback squares, with possibly the terminal object insterted at some places. Obviously, from the above proof, one gets a rather clumsy decomposition, e.g. with many unecessary terminal objects inserted. Is there any "better" decomposition (whatever this means, but e.g. a multiple pullback of three arrows should be decomposed into three pullback squares, and not seven of them)? Till Mossakowski -- Till Mossakowski Phone +49-421-218-4683 Dept. of Computer Science Fax +49-421-218-3054 University of Bremen till(a)tzi.de P.O.Box 330440, D-28334 Bremen http://www.tzi.de/~till 29-Mar-2002 15:14:54 -0400,1662;000000000000-00000000

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2WFTop: correction
by Giovanni Sambin 27 Mar '02

27 Mar '02

I am very sorry, here is the correct web address for: SECOND WORKSHOP ON FORMAL TOPOLOGY Venice, April 4-6, 2002 http://www.math.unipd.it/~logic 29-Mar-2002 15:14:49 -0400,1647;000000000000-00000000

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2WFTop: last announcement
by Giovanni Sambin 27 Mar '02

27 Mar '02

SECOND WORKSHOP ON FORMAL TOPOLOGY Auditorium S. Margherita, Campo S. Margherita Venice, April 4-6, 2002 A description of the workshop and updated information (including a map of Venice and indications on how to reach the sites of the workshop, Auditorium S. Margherita, Palazzo Zenobio, Fondazione Levi) can be found at http://www.math.unipd.it/~logic/wftop2. Notice that the day April 3 will be devoted to tutorials, by Peter Aczel, Bernhard Banaschewski, Giovanni Sambin and Silvio Valentini (abstracts of tutorials are now available at http://www.math.unipd.it/~logic/wftop2/tutorials.html) For late registration, send the form below to Damiano Macedonio, mace(a)dsi.unive.it. Name and Family name: Institution: Address: E-mail address: Date of arrival: Date of departure: If you need accomodation, contact directly Palazzo Zenobio (rooms with 3-4 beds, 25-30 euros each person, see the above web page for more detailed information).

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Lawvere's 14 Jan 2002 comments on Syntax vs Semantics....
by Steve Stevenson 26 Mar '02

26 Mar '02

I would like to read more in connection with his comment " semantics has been previously analyzed as the contravariant 2-functor...." In fact, I'd be interested to read anything on the categorical understanding of interpretations. best regards, steve 29-Mar-2002 15:14:42 -0400,804;000000000000-00000000

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Doctoral Programme of CP-2002: Call for Applications
by Constraint Programming 2002 20 Mar '02

20 Mar '02

=================================================================== Doctoral Programme of the Eighth International Conference on Principles and Practice of Constraint Programming (CP-2002) www.math.unipd.it/~frossi/cp2002-doctoral.html September 7-13, 2002 Cornell University Ithaca, NY, USA ================================================================== CALL FOR APPLICATIONS ================================================================== CP-2002 invites students to apply for the CP-2002 Doctoral Programme, which will provide an opportunity for a group of Ph.D. students to discuss and explore their research interests and career objectives with a panel of established researchers in Constraint Programming. The CP-2002 doctoral programme has the following objectives: to provide a setting for mutual feedback on participants' current research and guidance on future research directions; to develop a supportive community of scholars and a spirit of collaborative research; to support a new generation of researchers with information and advice on academic, research, industrial, and non-traditional career paths; to contribute to the conference goals through interaction with other researchers and participation in conference events. Program: The program will consists of students' presentations and tutorials given by senior researchers of the field. Submissions: We encourage submissions from Ph.D. students at any level, and from any topic area and methodology within constraint programming. On the basis of the submissions, the Organizing Committee will select a group of students that will be invited to present their work during the Doctoral Programme, and also to present a poster at the CP-2002 poster session. We expect a commitment from all participating students to attend the entire doctoral programme. Students accepted for participation in the Doctoral Programme will receive complimentary conference registration and a fixed allowance for travel/housing. The students' abstracts will be made available on the web and their printed version will be distributed on site. Applicants should submit by e-mail to frossi(a)math.unipd.it an extended abstract. It should be at most 6 pages in length (usual LNCS style format), and should describe original, unpublished work, completed or in progress, that is part of the doctoral work of the student. The extended abstract should be sent as a PostScript file. In addition, they should ask their dissertation advisor to send a letter of recommendation by e-mail to frossi(a)math.unipd.it. It must include an expected date for thesis submission. In addition, your advisor should indicate what he or she hopes you would gain from participation in the doctoral programme. This letter can be sent in as either a text or a PostScript file. Important Dates: -- May 1, 2002: Application Submission Deadline -- June 1, 2002: Acceptance Notification -- July 1, 2001: Final version due Organizing Committee: Carla Gomes (CP-2002 conference chair), Cornell University, USA Eugene C. Freuder, University of New Hampshire, USA Michela Milano, University of Bologna, Italy Francesca Rossi, University of Padova, Italy Pascal Van Hentenryck (CP-2002 program chair), Brown University, USA Toby Walsh, University of York, UK Inquiries: Additional information will be posted at the URL www.math.unipd.it/~frossi/cp2002-doctoral.html and may be obtained by contacting the chair of the organizing committee at frossi(a)math.unipd.it. 21-Mar-2002 03:47:46 -0400,3543;000000000000-00000000

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Re: Bigroupoids
by Ross Street 20 Mar '02

20 Mar '02

John Baez asked: >Does anyone know references that address the question of strictifying >weak 2-groupoids? Here by a "weak 2-groupoid" I mean something like a >bicategory in which every 2-morphism is invertible and every 1-morphism >is an equivalence, and by "strictifying" such a thing I mean finding a >biequivalent strict 2-category in which every 1-morphism and every >2-morphism is invertible. Dear John and others This is a question that people ask from time to time. Below is an answer I sent to Prof. Dr. Klaus Heiner Kamps back on Fri, 21 Feb 1997. Regards, Ross Dear Heiner The fact that every monoidal category V is equivalent to a strict monoidal category st(V) follows from Mac Lane's coherence theorem (see "Cats for the working mathematician" Springer GTM 5). Pare' & Mac Lane adapted that proof to a coherence theorem for bicategories JPAA 37 (1985) 59-80 and then it follows that every bicategory W is biequivalent to a 2-category st(W). [In fact, st(W) is easy to describe: the arrows are paths in W and the 2-cells are just 2-cells in W between the composites of the paths bracketed from the right.) But there are much quicker proofs of these facts. For the fact that every monoidal category V is equiv to a strict monoidal category e(V) see the early part of (with A. Joyal) Braided tensor categories, Advances in Math 102 (1993) 20-78; MR94m:18008. For the generalisation to bicategories, see page 3 of (with R. Gordon and A.J. Power) Coherence for tricategories, Memoirs of the American Math. Society 117 (1995) Number 558 (ISSN 0065-9266); MR96j:18002. So now suppose we have a bigroupoid B. By the above, B is biequivalent to a 2-category K. Since every 2-cell in B is invertible and every arrow in B is an equivalence, the same will be true in K. So it remains to show that K is biequivalent to a 2-groupoid. Consider a 2-category K' whose objects are those of K and whose arrows (f,g,a,b) : A --> B consist of adjunctions g -| f with unit a, counit b in K. The 2-cells (u,v) : (f,g,a,b) --> (f',g',a',b') are 2-cells u : f --> f', v : g' --> g which determine each other under the adjunctions. Compositions are the obvious ones. The 2-functor K' --> K taking (f,g,a,b) : A --> B to f : A --> B is a biequivalence (it is the identity on objects and an equivalence on each hom category). Yet, in K', each arrow is invertible (not merely an equivalence). This last construction is the several-object version of a special case of a construction used in the early part of (with A. Joyal) The geometry of tensor calculus II (in preparation). The approach I give above is how I would do it as a categorical exercise. A proof using cohomology of groups was given in (with A. Joyal) Braided monoidal categories, Macquarie Math Reports # 860081 (Nov. 1986). Hope this helps. --Ross 11-Mar-2002 02:53:17 -0400,1858;000000000000-00000000

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Book announcement: Foundations of OO Languages
by Kim Bruce 19 Mar '02

19 Mar '02

I'm happy to announce the publication of my new book on the foundations of object-oriented programming languages: Foundations of Object-Oriented Programming Languages: Types and Semantics Kim B. Bruce The MIT Press Copyright 2002 ISBN 0-262-02523-X You can find more information about the book, including the table of contents, preface, and 5 downloadable sample chapters in pdf format, at the web site: http://www.cs.williams.edu/~kim/FOOPL.html From the publisher: "In recent years, object-oriented programming has emerged as the dominant computer programming style, and object-oriented languages such as C++ and Java enjoy wide use in academia and industry. This text explores the formal underpinnings of object-oriented languages to help the reader understand the fundamental concepts of these languages and the design decisions behind them. The text begins by analyzing existing object-oriented languages, paying special attention to their type systems and impediments to expressiveness. It then examines two key features: subtypes and subclasses. After a brief introduction to the lambda calculus, it presents a prototypical object-oriented language, SOOL, with a simple type system similar to those of class-based object-oriented languages in common use. The text offers proof that the type system is sound by showing that the semantics preserves typing information. It concludes with a discussion of desirable features, such as parametric polymorphism and a MyType construct, that are not yet included in most statically typed object-oriented languages." The target audience for the book includes researchers, graduate students, and others interested in understanding the types, semantics, and language design issues relevant to the study of object-oriented languages. Links to order the book are available from the web page given above. Kim B. Bruce Professor of Computer Science Williams College 21-Mar-2002 18:51:03 -0400,3999;000000000000-00000000

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