June 2004 - Categories - categories.org.au

Questions on dinatural transformations.
by Noson Yanofsky 03 Jul '04

03 Jul '04

Hello, Two quick questions: a) It is well known that there is no vertical composition of dinatural transformations. How about horizontal composition? i.e. Given S,S':C^op x C---->B T,T':C^op x C ----> B^op U,U':B^op x B --->A \alpha: S--->S' dinat \alpha': T--->T' dinat and \beta: U--->U' dinat is there a \beta \circ (\alpha',\alpha) and is it dinat? It should be. But I can not seem to find the right definition. How about if we restrict to a nice category of moduals for a nice algebra over a nice field? Does that help? I was hoping that the category of small categories, functors and dinat transformations should be a graph-category (a category enriched over graphs) but am having a hard time finding what the composition is. Did someone write on these things? b) Also, I was wondering if anyone ever wrote about quasi-dinatural transformations. Those are dinats where the target category is a 2-category and the hexagon commutes up to a two cell. They show up in something I am working on. But they are very painful. Has anyone worked on such things? Any thoughts? All the best, Noson Yanofsky

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Grothendieck bio?
by Galchin Vasili 02 Jul '04

02 Jul '04

Hello, Does anybody know of a Grothendieck biography? For me many times it is helpful to read a bio to the historical development of a person's work. Thanks in advance, Bill Halchin

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Pullback & coproduct of toposes
by Barney Hilken 29 Jun '04

29 Jun '04

I don't have access to a decent library at the moment, and I can't afford a copy of the Elephant myself, so can anyone let me know: In the category of toposes and geometric morphisms, under what conditions is coproduct stable under pullback? Any reasonable conditions on the toposes or the morphisms would be helpful, but the more general, the better. Thanks, Barney.

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preprint: Filtered colimits in the effective topos
by jvoosten＠math.uu.nl 29 Jun '04

29 Jun '04

A 7-page paper entitled Filtered colimits in the effective topos can be downloaded from: http://www.math.uu.nl/people/jvoosten/effcolim.ps.gz Abstract: we are concerned with the problem whether there is a small full dense subcategory in the effective topos (which would give a nice embedding of Eff into a sheaf topos). Since this topos has enough projectives, we may assume that such a category consists of the \lambda-small projectives for some cardinal \lambda. Basically, there are two theorems: 1. For \lambda regular, uncountable: the \lambda -small projectives are dense, precisely if the constant objects functor \nabla :Sets --> Eff preserves \lambda-filtered colimits. 2. \nabla : Sets --> Eff does not preserve \omega _1-filtered colimits (hence, by 1., the countable projectives are not dense). Jaap van Oosten

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preprint: Neural Networks, Knowledge and Cognition...
by M. Healy 26 Jun '04

26 Jun '04

A technical report on a categorical model of the semantics of neural networks is now available on the Dspace archive in the collection 2004. To access it, go to the University of New Mexico site at https://repository.ece.unm.edu/dspace/ and search on http://hdl.handle.net/1928/33 . Here's an abstract: Neural Networks, Knowledge, and Cognition: A Mathematical Semantic Model Based upon Category Theory, by M. J. Healy and T. P. Caudell Category theory can be applied to mathematically model the semantics of cognitive neural systems. We discuss semantics as a hierarchy of concepts, or symbolic descriptions of items sensed and represented in the connection weights distributed throughout a neural network. The hierarchy expresses subconcept relationships, and in a neural network it becomes represented incrementally through a Hebbian-like learning process. The categorical semantic model described here explains the learning process as the derivation of colimits and limits in a concept category. It explains the representation of the concept hierarchy in a neural network at each stage of learning as a system of functors and natural transformations, expressing knowledge coherence across the regions of a multi-regional network equipped with multiple sensors. The model yields design principles that constrain neural network designs capable of the most important aspects of cognitive behavior. Please let me know right away if there are any problems. I'll warmly receive any questions or comments. - Mike

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CMCIM 2004 Workshop: Final Call for (Short) Papers and Participation
by Thomas Hildebrandt 24 Jun '04

24 Jun '04

FINAL CALL FOR (Short) PAPERS AND PARTICIPATION (Deadline July 1st): 3rd WORKSHOP ON: CATEGORICAL METHODS FOR CONCURRENCY, INTERACTION AND MOBILITY (CMCIM 2004), AUGUST 11, 2004 (www.itu.dk/research/theory/ctcs2004/cmcim.html) IT University of Copenhagen (ITU) Copenhagen, Denmark www.itu.dk - affiliated with the 10th conference in Category Theory and Computer Science (CTCS 2004) ,August 12th-14th, and Graduate Student Summer School in Category Theory and Computer Science, August 9th-11th. ------------------------------------------------------------------------ ------------------------------------------ NEW: - Extended workshop submission deadline: July 1st - Accepted papers and abstracts for invited talks for CTCS available at www.itu.dk/research/theory/ctcs2004/ ------------------------------------------------------------------------ ------------------------------------------- We invite submissions of short, extended abstracts (less than 5 pages) for an informal half-day workshop on Categorical Methods in Concurrency, Interaction and Mobility. The workshop has previously been held in connection with CONCUR 2002 and CONCUR 2003. There will be no formal proceedings of the workshop, informal proceedings will be distributed at the workshop. Thus, accepted material may be published elsewhere at a later date. Submissions may present status reports, recent results, challenges, or work in progress Topics of interest include: • categorical algebras of processes • categorical methods in game semantics and geometry of interaction • categorical models of term/graph rewriting or rewriting logic • Chu spaces • coalgebras, bialgebras, coinduction • comparing models of concurrency • enriched categories of processes • interaction categories • bigraphs • presheaf semantics Workshop PARTICIPATION IS FREE, but REQUIRES REGISTRATION before 1st of July, by SENDING AN EMAIL to hilde(a)itu.dk, containing `CMCIM2004-registration' in the subject, and your full name and affiliation in the body. Submissions should be sent before July 1st, as PostScript or PDF file to: hilde(a)itu.dk, containing `CMCIM-submission' in the subject, and in the body the full names of the author(s), title, and a text-only abstract. CMCIM 2004 Workshop Organizers: Thomas Hildebrandt Alexander Kurz More information and registration at: http://www.itu.dk/research/theory/ctcs2004/cmcim.html --------------------------------------- SPONSORSHIP The conference and summer school are APPSEM-II events, and are as the workshop sponsored by the FIRST graduate school (www.first.dk) and the Department of Theoretical Computer Science at IT University of Copenhagen (http://www.itu.dk/Internet/sw648.asp)

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CTCS '04: Accepted papers and Final Call for Participation
by Thomas Hildebrandt 24 Jun '04

24 Jun '04

FINAL CALL FOR PARTICIPATION (Deadline July 1st) 10th CONFERENCE ON CATEGORY THEORY AND COMPUTER SCIENCE (CTCS'04) AUGUST 12-14, 2004 www.itu.dk/research/theory/ctcs2004/ and GRADUATE STUDENT SUMMER SCHOOL AUGUST 9-11, 2004 www.itu.dk/research/theory/ctcs2004/summerschool.html and 3rd WORKSHOP ON CATEGORICAL METHODS FOR CONCURRENCY, INTERACTION AND MOBILITY (CMCIM 2004) AUGUST 11, 2004 www.itu.dk/research/theory/ctcs2004/cmcim.html IT University of Copenhagen (ITU) Copenhagen, Denmark www.itu.dk ------------------------------------------------------------------------ --- NOTE: The registration deadline at July 1st is approaching NEW: List of accepted papers for CTCS NEW: Abstracts of invited talks for CTCS ------------------------------------------------------------------------ --- Important Dates: * April 16th, 2004: CTCS Submission deadline (closed) * June 1st, 2004: CTCS Notification of authors of accepted papers * July 1st, 2004: Submission of abstracts for CMCIM Workshop (extended) * July 1st, 2004: CTCS Registration (and special hotel rates) deadline ------------------------------------------------------------------------ ---- CTCS'04 is the 10th Conference on Category Theory and Computer Science, with the purpose to advance the foundations of computing using the tools of category theory. Invited Speakers for the CTCS 2004 Conference: * Francois Bergeron (Quebéc) * Martin Hyland (Cambridge) * Robin Milner (Cambridge) * Andrew Pitts (Cambridge) * Thomas Streicher (Darmstadt) Abstracts at: http://www.itu.dk/research/theory/ctcs2004/InvitedTalks.html Typical topics at CTCS include 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 conferences have been held in Guildford (Surrey), Edinburgh (twice), Manchester, Paris, Amsterdam, Cambridge, S. Margherita Ligure (Genova), and Ottawa. More information and registration form at: http://www.itu.dk/research/theory/ctcs2004/ ---------------------------------------------------------------------- CTCS 2004 PhD SUMMER SCHOOL The summer school is aimed at both graduate and undergraduate students, with basic knowledge of category theory. The school will offer mini-courses (5 lectures each) in: * Stone Duality, Coalgebras, and Modal Logic (Alexander Kurz) * Game Semantics (Guy McCusker) * Operational Semantics (Pawel Sobocinski) * Categorical Models for Concurrency (Thomas Hildebrandt) More information and registration at: http://www.itu.dk/research/theory/ctcs2004/summerschool.html -------------------------------------------------------------------- CMCIM 2004 WORKSHOP (short abstract deadline: July 1st) In between the summer school and the CTCS conference, August 11th, there will be an informal half-day workshop on Categorical Methods in Concurrency, Interaction and Mobility. The workshop has previously been held in connection with CONCUR 2002 and CONCUR 2003. We invite submissions of short extended abstracts (less than 5 pages), presenting status reports, recent results, challenges or work in progress. There will be no formal proceedings of the workshop, informal proceedings will be distributed at the workshop. Thus, accepted material may be published elsewhere at a later date. Workshop participation is FREE, but requires registration before 1st of July. Submissions should be sent before 1st of July (extended). More information and registration at: http://www.itu.dk/research/theory/ctcs2004/cmcim.html ----------------------------------------------------------------- Organisation: CTCS 2004 PROGRAMME COMMITTEE: Lars Birkedal, Chair (IT University of Copenhagen) Marcelo Fiore (University of Cambridge) Masahito Hasegawa (Kyoto University) Bart Jacobs (University of Nijmegen) Ugo Montanari (University of Pisa) Valeria de Paiva (Palo Alto Research Center) Dusko Pavlovic (Kestrel Institute) John Power (University of Edinburgh) Edmund Robinson (Queen Mary, University of London) Peter Selinger (University of Ottawa) CTCS ORGANIZING COMMITTEE E. Moggi, Chair, (Genova) S. Abramsky (Oxford) P. Dybjer (Chalmers) B. Jay (Sydney) A. Pitts (Cambridge) CTCS 2004 LOCAL ORGANIZING COMMITTEE C. Butz T. Hildebrandt A.L. Moerk CMCIM 2004 Workshop Organizers: Thomas Hildebrandt Alexander Kurz --------------------------------------- SPONSORSHIP The conference and summer school are APPSEM-II events, sponsored by the FIRST graduate school (www.first.dk) and the Department of Theoretical Computer Science at the IT University of Copenhagen (http://www.itu.dk/Internet/sw648.asp)

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interruption
by Bob Rosebrugh 16 Jun '04

16 Jun '04

The categories moderator will be out of email contact June 18-29, 2004. Postings submitted to Categories during that period will be distributed June 30. Best wishes, Bob Rosebrugh

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LICS 2004 - Call for Participation
by Alex Simpson 10 Jun '04

10 Jun '04

The deadline for early registration for LICS 2004 is *June 15, 2004*. ------------------------------------------------------------------------ CALL FOR PARTICIPATION Nineteenth Annual IEEE Symposium on LOGIC IN COMPUTER SCIENCE (LICS 2004) July 13th - 17th, 2004, Turku, Finland http://www.lfcs.informatics.ed.ac.uk/lics/ The LICS Symposium is an annual international forum on theoretical and practical topics in computer science that relate to logic in a broad sense. For registration visit http://www.math.utu.fi/ICALP04/registration.html The deadline for early registration is June 15, 2004. Collocated events: ICALP'04 will be collocated with LICS'04; for details see http://www.math.utu.fi/ICALP04/. Invited Speakers: The following distinguished speakers will give invited talks at LICS 2004: Samson Abramsky (U. of Oxford), Robert Harper (Carnegie Mellon University), Alexander Razborov (IAS, Princeton, and Steklov Math. Inst., Moscow), Davide Sangiorgi (U. di Bologna), Igor Walukiewicz (U. Bordeaux), and Mihalis Yannakakis (Stanford U.). For full program visit LICS website http://www.lfcs.informatics.ed.ac.uk/lics/ Program Committee: Rajeev Alur, U. of Pennsylvania Andrew Appel, Princeton U. Albert Atserias, UPC, Barcelona Franz Baader, Dresden U. Samuel Buss, U. of California, San Diego Roberto Di Cosmo, U. de Paris VII Gilles Dowek, Ecole Polytechnique, Paris Harald Ganzinger, MPI, Saarbruecken (chair) Martin Hofmann, LMU Muenchen Achim Jung, U. of Birmingham Kim Larsen, Aalborg U. Leonid Libkin, U. of Toronto Rocco de Nicola, U. di Firenze Damian Niwinski, Warsaw U. Prakash Panangaden, McGill U., Montreal Albert Rubio, UPC, Barcelona Vitaly Shmatikov, SRI International Moshe Vardi, Rice U., Houston Helmut Veith, TU Wien Andrei Voronkov, U. of Manchester Conference Chair: Lauri Hella Department of Math., Stat., and Phil. Kanslerinrinne 1 33014 University of Tampere, Finland Email: lauri.hella(a)uta.fi Workshops Chair: Phil Scott, U. of Ottawa Email: phil(a)site.uottawa.ca Publicity Chair: Alex Simpson, U. of Edinburgh Email: Alex.Simpson(a)ed.ac.uk General Chair: Phokion G. Kolaitis, UC Santa Cruz Email: kolaitis(a)cse.ucsc.edu Organizing Committee: S. Abramsky, A. Broder, E. Clarke, A. Felty, H. Ganzinger, H. Gabow, J. Halpern, L. Hella, U. Kohlenbach, P. Kolaitis (chair), D. Leivant, G. Longo, H. Mairson, A. Middeldorp, J. Mitchell, M. Nielsen, P. Panangaden, G. Plotkin, F. Pfenning, P. Scott, R. Shore, A. Simpson, I.A. Stewart. Advisory Board: Y. Gurevich, C. Kirchner, D. Kozen, U. Martin, L. Pacholski, V. Pratt, A. Scedrov, M.Y. Vardi, G. Winskel. Sponsorship: The symposium is sponsored by the IEEE Technical Committee on Mathematical Foundations of Computing in cooperation with the Association for Symbolic Logic, and the European Association for Theoretical Computer Science.

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New OUP Monograph: Reductive Logic and Proof-search.
by David J. Pym 08 Jun '04

08 Jun '04

Readers of these lists may be interested in the following new monograph in OUP's Oxford Logic Guides series (number 45): Reductive Logic and Proof-search: Proof Theory, Semantics, and Control by David Pym and Eike Ritter. http://www.oup.co.uk/isbn/0-19-852633-4 also linked from http://www.bath.ac.uk/~cssdjp Contents: Preface Foreword by Lincoln Wallen 1 Deductive Logic, Reductive Logic, and Proof-search 2 Lambda-calculi for Intuitionistic and Classical Proofs 3 The Semantics of Intuitionistic and Classical Proofs 4 Proof Theory for Reductive Logic 5 Semantics for Reductive Logic 6 Intuitionistic and Classical Proof-search and Their Semantics References Index With thanks, David Pym -- Prof. David J. Pym Telephone: +44 (0)1 225 38 3246 Professor of Logic & Computation Facsimile: +44 (0)1 225 38 3493 University of Bath Email: d.j.pym(a)bath.ac.uk Bath BA2 7AY, England, U.K. Web: http://www.bath.ac.uk/~cssdjp

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