May 2004 - Categories - categories.org.au

parameterised accessiblity
by V. Schmitt 21 May '04

21 May '04

Dear all, I am pleased to advert a paper that has been for (too)long in limbo. I eventually put the paper on the math archive in march http://arXiv.org/abs/math.CT/0403164 I acknowledge F. Borceux that suggested me a major improvement. This work was first presented in Amiens in Nov. 03. and at the last PSSL in Cambridge (Thank you all for your feedback). Here is a short abstract. The notion of P-flatness and Q-acessibility are introduced where the prameters P and Q stand for family of indexes in the sense of Borceux-Kelly. The following points are proved. Fixing a family P of indexes and Q denoting the family of P-flat indexes: - for a small category A, a presheaf on A is P-flat if and only if it is a Q-colimit of representables. - The full subcategory of the category of presheaves on a small A generated by P-flat presheaves is the free Q-cocompletion of A. Conversely Q-accessible categories occur as categories of P-flat presheaves on small A's. This correspondence yields meaningful internal description for free-Q-cocomplete objects for suitable Q's. For instance Lawvere's Cauchy-complete categories are exactly the full subcategories of P0-flat presheaves on small A's for P0 the family of ALL indexes. Remarkably this theory of accessibility extends to the enriched context (the only constraint on the base V is that it should be sym. & closed). Actually it is very likely that the whole theory might be developed in a 2-category with a Yoneda structure. Other completions by means of P-flat preshaves may be considered. For instance one obtains this way completions of metric spaces in terms of asymmetric Cauchy-filters. One also retrieves the algebraic completions of partial orders. Best regards to you all, Vincent.

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Preprint: The shape of a category up to directed homotopy
by Marco Grandis 20 May '04

20 May '04

The following preprint is available: M. Grandis, The shape of a category up to directed homotopy, Dip. Mat. Univ. Genova, Preprint 509 (May 2004), 44 p. Abstract. This work is a contribution to a recent field, Directed Algebraic Topology. Categories which appear as fundamental categories of 'directed structures', e.g. ordered topological spaces, have to be studied up to appropriate notions of directed homotopy equivalence, wider than ordinary equivalence of categories. Here we introduce 'past' and 'future equivalences' of categories - sort of symmetric versions of an adjunction - and use them and their combinations to get 'directed models' of a category; in the simplest case, these are the join of the least full reflective and the least full coreflective subcategory. MSC: 55Pxx, 18A40, 68Q85. Keywords: homotopy theory, adjunctions, reflective subcategories, directed algebraic topology, fundamental category, concurrent processes . Available as pdf or ps: http://www.dima.unige.it/~grandis/Shp.pdf http://www.dima.unige.it/~grandis/Shp.ps With best regards Marco Grandis Dipartimento di Matematica Universita` di Genova via Dodecaneso 35 16146 GENOVA, Italy e-mail: grandis(a)dima.unige.it tel: +39.010.353 6805 fax: +39.010.353 6752 http://www.dima.unige.it/~grandis/

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the graph of an adjunction
by Marco Grandis 19 May '04

19 May '04

An adjunction has a functorial mono-epi factorization, so natural to be likely well known. I would like to have a *reference* for this. Let F -| G, where F: X --> A and G: A --> X. Then our adjunction has an obvious factorisation through the isomorphic comma categories: W = (F | A) = (X | G) using the full coreflective embedding of X in W, and the full reflective embedding of A in W. W might be called the 'graph' of the adjunction; or has it been called differently? R. Pare and myself, we have used a similar result for double categories, for a colax double functor left adjoint to a lax one: Thm. 3.7 in 'Adjoints for double categories', to appear in 'Cahiers'. But I need now the result for ordinary categories, for applications to directed homotopy. Best regards Marco Grandis

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jobs: Professorships, Readerships, Lectureships, Tutorships
by Markus Michelbrink 17 May '04

17 May '04

** With apologies for multiple posting ** Professorships, Readerships, Lectureships, Tutorships. ====================================================== The department of computer science at Swansea (Wales, UK) is currently advertising academic positions at all levels. We hope expecially to expand our groups in visual computing and in logic/theoretical computer science. Our department was rated 5 in the last research assessment exericse. It has a strong group in logic and theoretical computer science which is amongst the biggest in UK. The members of that group are Ulrich Berger (proof theory, computability theory, type theory), Phil Grant (artificial intelligence), Andy Gimblett (algebraic specification), Neal Harman (hardware verification, models of computation, algebraic specification), Oliver Kullmann (satisfiability problems), Markus Michelbrink (category theory, proof theory, type theory), Faron Moller (automata theory, modal and temporal logic), Markus Roggenbach (algebraic specification), Monika Seisenberger (proof theory, type theory, computability theory), Anton Setzer (proof theory, type theory) and John Tucker (algebraic specification, algebraic methods, computability theory). We have as well strong links to the mathematics department, with Roger Hindley (lambda-calculus) and Jiang-Lun Wu (nonstandard analysis). The deadline for application is 25 June 2004 (I have been signalled that late applications might still be acceptable). The official advertisements can be found at http://www.jobs.ac.uk/jobfiles/IS433.html and http://www.jobs.ac.uk/jobfiles/IS434.html -- ----------------------------------------------------------------------------- Anton Setzer Telephone: Department of Computer Science (national) (01792) 513368 University of Wales Swansea (international) +44 1792 513368 Singleton Park Fax: Swansea SA2 8PP (national) (01792) 295708 UK (international) +44 1792 295708 Visiting address: Email: a.g.setzer(a)swan.ac.uk Faraday Building, WWW: Computer Science Dept. http://www.cs.swan.ac.uk/~csetzer/ 2nd floor, room 211. ---------------------------------------------------------------------------- -- ------------------------------------------------------- -- Dr. Markus Michelbrink Dept. of Computer Science University of Wales Swansea Singleton Park Swansea SA2 8PP United Kingdom

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UNIF 2004 workshop @ IJCAR : extended deadline
by Ralf Treinen 17 May '04

17 May '04

Call for Papers/Abstracts/System descriptions ***** Deadline extentended until Friday, Mai 21 ******* UNIF 2004 18th International Workshop on Unification July 4-5, 2004, Cork, Ireland Affiliated with IJCAR'04 http://www.faculty.iu-bremen.de/mkohlhase/event/unif04/ UNIF is the main international meeting on unification. Unification is concerned with the problem of identifying given terms, either syntactically or modulo a given logical theory. Syntactic unification is the basic operation of most automated reasoning systems, and unification modulo theories can be used, for instance, to build in special equational theories into theorem provers. The aim of UNIF 2004, as that of the previous meetings, is to to bring together people interested in unification, present recent (even unfinished) work, and discuss new ideas and trends in unification and related fields. In particular, it is intended to offer a good opportunity for young researches and researchers working in related areas to get an overview of the current state of the art in unification theory and get in contact with the experts in the field. ---------------------------------------------------------------------- TOPICS OF INTEREST ---------------------------------------------------------------------- A non-exclusive list of topics of interest is: * Unification * E-unification * Unification Algorithms * Higher-Order Unification * String Unification * Context Unification * Combination problems * Disunification * Typed Unification * Related Topics * Constraint Solving * Tree Descriptions * Matching * Narrowing * Applications * Type Checking and Type Inference * Automated Deduction * Rewriting * Functional and Logic Programming * Grammars * Computational Linguistics * Implementations ---------------------------------------------------------------------- INVITED SPEAKERS ---------------------------------------------------------------------- There will be two invited speakers. ---------------------------------------------------------------------- IMPORTANT DATES ---------------------------------------------------------------------- NEW: Deadline for electronic submission: Friday, May 21, 2004 Email: unif04(a)iu-bremen.de Notification of acceptance: Monday, May 24, 2004 Deadline for camera-ready papers: Monday, June 7, 2004 Workshop: July 4 - 5, 2004 ---------------------------------------------------------------------- SUBMISSION DETAILS ---------------------------------------------------------------------- Authors are invited to submit via email an abstract (1-5 pages), a paper (no longer than 15 pages), or a system description (no more than 5 pages) in Postscript or PDF format to: unif04(a)iu-bremen.de before May 14, 2004. Authors are encouraged to use LaTeX2e and the Springer llncs class. ---------------------------------------------------------------------- PUBLICATION ---------------------------------------------------------------------- Accepted papers, abstracts and system descriptions will be included in the proceedings which will be available at the workshop. ---------------------------------------------------------------------- ORGANIZING COMMITTEE ---------------------------------------------------------------------- Michael Kohlhase (International University Bremen, Germany) Hitoschi Ohsaki (National Institute of Advanced Industrial Science and Technology, Amagasaki, Japan) Steve Prestwich (Universtity College, Cork, Ireland) Ralf Treinen (Ecole Normale Superieure, Cachan, France) Manfred Schmidt-Schauss (Johann Wolfgang Goethe-Universit"at Frankfurt am Main, Germany) -- Ralf Treinen Laboratoire Spécification et Vérification CNRS & École Normale Supérieure de Cachan http://www.lsv.ens-cachan.fr/~treinen

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SOS Workshop - final CfP
by Wan.Fokkink＠cwi.nl 17 May '04

17 May '04

Call for Papers Structural Operational Semantics http://www.cs.auc.dk/~luca/SOS-WORKSHOP/ A Satellite Workshop of CONCUR 2004 30 August, 2004, London, United Kingdom 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 generalization 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 constructs. The proposed SOS workshop aims to be a forum for researchers, students and practitioners interested in new developments and directions for future investigation in the field of structural operational semantics. One of the specific goals of the workshop is to establish synergies between the concurrency and programming language communities working on the theory and practice of SOS. The workshop will also mark the publication of a special issue of the Journal of Logic and Algebraic Programming, devoted to SOS. Together with original research papers on SOS, this special issue will feature a definitive version of Gordon Plotkin's 1981 DAIMI memo on SOS, together with a piece by Plotkin on the origins of SOS. Specific topics of interest include (but are not limited to): * programming languages * process algebras * higher-order formalisms * rule formats for operational specifications * meaning of operational specifications * comparisons between denotational, axiomatic and SOS * compositionality of modal logics with respect to operational specifications * congruence with respect to behavioural equivalences * conservative extensions * derivation of proof rules from operational specifications * software tools that automate, or are based on, SOS Papers reporting on applications of SOS to software engineering and other areas of computer science are welcome. Paper submission: We solicit unpublished papers reporting on original research on the general theme of SOS. Prospective authors are invited to submit a pdf or postscript file with their extended abstract, whose length should not exceed 15 pages, by email to all of the co-chairs at their respective email addresses. The email message with the submission should also include, in plain text, contact information for the author(s), together with the title and abstract of the submission. Submissions are to be received by Sunday, 6 June, 2004. Authors will be notified of acceptance by Wednesday, 30 June, 2004. Submissions from the PC members are allowed. Proceedings: Preliminary proceedings containing the abstracts of the talks will be published as a volume in the BRICS Notes Series, and will be available at the meeting. The final proceedings of the workshop will appear as a volume in the ENTCS series. If the quality and quantity of the submissions warrant it, the co-chairs plan to arrange a special issue of an archival journal devoted to full versions of selected papers from the workshop. Important Dates: * Submission: Sunday 6 June 2004 * Notification: Wednesday 30 June 2004 * Final version: Friday July 16 2004 * Workshop: Monday 30 August 2004 Invited Speakers: Andrew Pitts (Cambridge, United Kingdom) Gordon Plotkin (Edinburgh, United Kingdom) (To be confirmed) Program Committee: Luca Aceto (BRICS, Aalborg, Denmark, co-chair) Wan Fokkink (CWI, The Netherlands, co-chair) Rob van Glabbeek (NICTA, Sydney, Australia) Ralf Laemmel (CWI, The Netherlands) Peter Mosses (BRICS, Aarhus, Denmark) David Sands (Chalmers, Sweden) Alex Simpson (Edinburgh, United Kingdom) Simone Tini (Insubria, Italy) Irek Ulidowski (Leicester, United Kingdom, co-chair) Erik de Vink (Eindhoven, The Netherlands) Organizing Committee: Luca Aceto, email: luca AT cs.auc.dk, Wan Fokkink, email: wan AT cwi.nl, Irek Ulidowski, email iu3 AT mcs.le.ac.uk

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Error in "Omega Categories I"
by Topos8＠aol.com 16 May '04

16 May '04

Peter May and another colleague have kindly pointed out to me that section 6 of my paper "Omega Categories I" is complete rubbish. In that section I claimed to offer a simple proof of the Baez-Dolan stabilization conjecture but clearly I have completely misunderstood the substance of that conjecture. I expect to have more to say on this subject another day but meantime will be content with the observation that the rest of the paper is independent of the seriously flawed section 6. I offer my apology to those who were mislead or confused by that section of the paper and would like to thank Peter et. al. for their interest and help. Carl Futia

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CFP: Logic, Games and Philosophy: Foundational Perspectives
by Peter McBurney 14 May '04

14 May '04

* With apologies for multiple posting ** CALL FOR PAPERS Logic, Games and Philosophy: Foundational Perspectives Prague International Colloquium www.flu.cas.cz/Logica/Aconf/col2004.html Organised by Department of Logic, Institute of Philosophy, Academy of Sciences of the Czech Republic, and Department of Philosophy, University of Helsinki 28 September â€“ 1 October 2004, Prague, Czech Republic SYNOPSIS Games, like logics, are tools for investigating the world, language, and their relationship. Semantic, dialogic, evolutionary, interrogative, argumentative, and pragmatic methods have been included into the toolkit. Following the recent increase in investment on games and game-theoretic methods in logic, language, computation and communication, we still need a better understanding of the possibilities of forming converging methodologies underlying these diverse contemporary currents. The purpose of the Prague Conference on Logic, Games and Philosophy: Foundational Perspectives is to explore the interfaces between logic and games with the eye on philosophical, methodological and foundational issues. Preference is given to papers that make a definite contribution to philosophical, methodological and foundational issues underlying game-theoretic approaches to logical, computational or linguistic research, including relevant historical and philosophical issues on the Theory of Games itself. Relevant topics include, but are not limited to: * Wittgenstein, C. S. Peirce * Language Games * Game-Theoretic Semantics * Dialogue Games * Interrogative Games/Philosophy of Science * Evolutionary Games * Diachronicity/Semantic-Pragmatic Change * Game-Theoretic Methods in Logic, Language, Computation, Communication Among the invited speakers of the colloquium are Mathieu Marion (QuÃ©bec Ã MontrÃ©al), Shahid Rahman (Lille 3), Gabriel Sandu (Helsinki), Wim Veldman (Nijmegen). Potential contributors are asked to submit a two page (including references) abstract; the deadline is 15 June 2004. Abstracts are to be submitted by e-mail (preferably as PDF, PS or MS Word files) prepared for anonymous reviewing. (To prevent problems caused by e-mail failures, the receipt of every abstract will be confirmed within one week.) Notification of acceptance will be distributed by 15 July 2004. Contributed papers are scheduled for approx. 40 minutes (including discussion). Please direct your abstracts to: lanna(a)site.cas.cz The proceedings of the Prague International Colloquium will be offered to Kluwer Academic Publishers for inclusion in their series Logic, Epistemology and the Unity of Science (the papers will be reviewed). If you need more information, please contact us at: lanna(a)site.cas.cz The conference website is http://www.flu.cas.cz/Logica/Aconf/col2004.html Program Committee: Gabriel Sandu (Chair, Helsinki) Johan van Benthem (Amsterdam, Stanford) Mathieu Marion (QuÃ©bec Ã MontrÃ©al) Jaroslav Peregrin (Prague) Ahti-Veikko Pietarinen (Helsinki) Shahid Rahman (Lille 3) Tero Tulenheimo (Helsinki) Wim Veldman (Nijmegen) Organising Committee: Ondrej Majer (Prague) Ahti-Veikko Pietarinen (Helsinki) Tero Tulenheimo (Helsinki) --------------------------------------------------------------------------

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FMCS 2004
by robin＠cpsc.ucalgary.ca 13 May '04

13 May '04

Final announcement for FMCS 2004: ------------------------------------------------------------------------- FFFFFFF M M CCC SSS F MM MM C S FFFFF M MM M C SSS F M M C S F M M CCC SSS 2004 (CALGARY) ------------------------------------------------------------------------- http://pages.cpsc.ucalgary.ca/~robin/FMCS/FMCS_04/index.html ------------------------------------------------------------------------- This year's meeting on Foundational Methods in Computer Science (FMCS 2004) will be hosted by the Programming Languages Group at the University of Calgary, June 4th -- June 6th and will be held at the Kananaskis Field Station. Next years meeting will be in Vancouver at UBC. ------------------------------------------------------------------------- FOUNDATIONAL METHODS IN COMPUTER SCIENCE The workshop is an informal meeting to bring together researchers in mathematics and computer science with a focus on the applications of category theory in computer science. It is a three day meeting, June 4th-6th which includes tutorials by: -- Andrea Schalk: Double Gluing -- Pieter Hofstra: Realizability -- Phil Scott: Geometry of Interaction -- Ernie Manes: Guarded Semigroups and has two days of contributed research talks. If you wish to participate please let us know before 21st May 2004. If, in addition, you wish to give a presentation you must provide an abstract and title to Robin Cockett or Craig Pastro (see e-mail address below) before Friday 21st May (although we appreciate notification on this as early as possible). Student participation at FMCS is particularly encouraged. __________________________________________________________ Organizer: Robin Cockett (robin at cpsc.ucalgary.ca) Local organizer: Craig Pastro (pastroc at cpsc.ucalgary.ca)

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note, review, preprint
by Marta Bunge 12 May '04

12 May '04

This is to call attention to three recent items in my homepage. 1) A note: "On a class of pullbacks preserved by the presheaf functor" (with J.Funk, in connection with ongoing work with M.Jibladze and T. Streicher). http://www.math.mcgill.ca/~bunge/pbthm.dvi (pbthm.ps) 2) A review of F.W.Lawvere and S.Schanuel, "Matematicas Conceptuales", Siglo XXI, Mexico, 2002. In Spanish. (Translation only on request and eventually.) http://www.math.mcgill.ca/~bunge/LS.dvi (LS.ps, LS.pdf) 3) A preprint "Definable completeness" (with J.Funk, M.Jibladze, and T. Streicher), to appear in Cahiers de Top. et Geo. Diff. Categoriques. http://www.math.mcgill.ca/~bunge/defcomp.dvi (defcomp.ps) Please let me know if you have any problems downloading. Greetings, Marta Bunge **************************************************************************** Marta Bunge Professor Emerita Dept of Mathematics and Statistics McGill University 805 Sherbrooke St. West Montreal, QC, Canada H3A 2K6 T: (514) 398-3810 F: (514) 933-8741 marta.bunge(a)mcgill.ca http://www.math.mcgill.ca/~bunge ************************************************

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