February 1997 - Categories - categories.org.au

AMS Special session in categories
by Robert A. G. Seely 13 Mar '97

13 Mar '97

Mike Barr has asked me to relay the following information (my source was the following URL: <http://www.ams.org/amsmtgs/>) The pertinent fact of interest to this list is the special session on Category Theory and its Applications which he, Ieke Moerdijk, and Myles Tierney are organizing. For further information, contact the organizers; updates will be posted to this list as appropriate. = rags = -------------------------------------------------------------------------- Notice of AMS Meeting September 26-28, 1997 Montreal, Quebec Canada (1997 Fall Eastern Sectional Meeting) Meeting # 924, Notices Program Issue: October 1997 Deadline for Contributed Papers for consideration in Special Sessions: May 1, 1997 Deadline for Abstract Submission: June 26, 1997 Special Sessions and Invited Addresses Invited Addresses Jacob E. Goodman, City University of New York, City College , Title to be announced Dieter Kotschick, University of Basel, Switzerland , Title to be announced Francois Lalonde, University of Quebec at Montreal , Title to be announced I. Moerdijk, University of Utrecht, Netherlands , Title to be announced Special Session on Category Theory and Its Applications Organizers: Michael Barr, McGill University barr(a)triples.math.mcgill.ca Ieke Moerdijk, University of Utrecht. Netherlands moerdijk(a)math.ruu.ne Myles Tierney, Rutgers University tierney(a)math.rutgers.edu

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CTCS'97 conference - change of deadline
by Eugenio Moggi 27 Feb '97

27 Feb '97

CATEGORY THEORY AND COMPUTER SCIENCE (CTCS'97) 4-6 SEPTEMBER 1997, S. MARGHERITA LIGURE (GENOA), ITALY URL: "http://www.disi.unige.it/conferences/ctcs97/" The deadline for electronic submission has been postponed to the 4th of March. Please look at the conference URL for the Call for Papers. Best Regards Eugenio Moggi

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Category Theory and Databases
by categories 27 Feb '97

27 Feb '97

Date: Thu, 13 Feb 1997 15:12:56 UTC From: Jose I. Bravo <jibravo(a)ull.es> I am very interested in the application of Category Theory in the area of Databases. Could anybody help me to obtain references on this subject? Thanks in advance. -------------------------------------------------------------------- Jose I. Bravo phone: +34 +22 603306 Dpt. Estadistica, I.O. y Computacion fax: +34 +22 635358 Universidad de La Laguna email: jibravo(a)ull.es Tenerife (Canary Islands) SPAIN --------------------------------------------------------------------

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Express97
by joachim＠sics.se 27 Feb '97

27 Feb '97

*********************** * E X P R E S S 9 7 * *********************** Preliminary Call for Papers for the 4th Workshop on EXPRESSIVENESS IN CONCURRENCY 8-12 September 1997, Santa Margherita Ligure, Italy Deadline for submissions: 2 MAY 1997 See also: ********************************************** * http://www.sics.se/~joachim/Express97.html * ********************************************** SCOPE This meeting aims at a general understanding of the interconnections and relations between formal systems, ranging from programming languages for concurrency to logics. More specifically, we consider methods to compare concurrent programming concepts, such as imperative programming, logic programming, functional programming, concurrent programming, object-oriented programming, dataflow, and the various combinations thereof, on the basis of their relative expressive power. We also consider associated mathematical formalisms such as process algebras, Petri nets, modal logics, rewrite systems etc. from this point of view. The meeting is mainly intended for active researchers to get together and discuss their latest results and methods. It is also the final meeting of the HCM project EXPRESS, which has been active with this focus since 1994. CO-CHAIRS: Catuscia Palamidessi, University of Genova, Italy email: catuscia(a)disi.unige.it Joachim Parrow, Royal Inst. of Technology, Sweden email: joachim(a)it.kth.se INVITED SPEAKERS (list not yet final. The following have accepted): Ralph BACK Ugo MONTANARI Amir PNUELI Vaughan PRATT Colin STIRLING Many speakers from the EXPRESS sites will also attend. The URL above has a tentative list of participants from the project. SUBMISSIONS We seek research or expository papers on at most 15 pages (12pt font) submitted electronically (postscript format) no later than ** 2 MAY 1997 ** Notification of acceptance is 15 June and deadline for final versions is 31 August. Information about the submission procedure will be available soon at http://www.disi.unige.it/person/PalamidessiC/EXPRESS97/submit.html For additional information send email to expr97(a)venus.disi.unige.it The proceedings will appear as a volume in the Electronic Notes of Theoretical Computer Science. We are currently investigating the possibility of having a special issue of selected papers to appear in a well-established computer science journal. PROGRAMME COMMITTEE Luca Aceto, University of Aalborg, DK Jan Bergstra, University of Amsterdam, NL Eike Best, University of Oldenburg, DE Frank de Boer, University of Utrecth, NL Ilaria Castellani, INRIA Sohia-Antipolis, FR Philippe Darondeau, INRIA Rennes, FR Rocco De Nicola, University of Florence, IT Ursula Goltz, University of Hildesheim, DE Jan Willem Klop, CWI, NL Catuscia Palamidessi (Co-chair), University of Genova, IT Joachim Parrow (Co-chair), Royal Inst. of Technology, SE Frits Vaandrager, University of Nijmegen, NL VENUE The conference will take place at Hotel Regina Elena in Santa Margherita Ligure. This is a 4 stars hotel with private beach and conference facilities, which will also provide accommodation for most of the participants. Santa Margherita Ligure is a beautiful sea resort in Liguria, on the Riviera di Levante. It is very close to Portofino promontory and about 30 km east of Genova. The nearest international airport is in Genova with direct connections to Zurich, Paris, London, Munich and other European towns. Between Santa Margherita Ligure and Genova there are good train connections.

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PSSL 64
by koslowj＠iti.cs.tu-bs.de 26 Feb '97

26 Feb '97

PERIPATETIC SEMINAR ON SHEAVES AND LOGIC 64th meeting - first announcement The 64th meeting of the seminar will be held at the Department of Theoretical Computer Science of the Technical University in Braunschweig, Germany, over the weekend of May 10-11, 1997. The seminar welcomes talks using or addressing category theory or logic, either explicitly or implicitly, in the study of any aspect of mathematics or science. On Friday, May 9, 13:00, i.e., before the regular seminar, there will be an official Colloquium Talk by Maria Cristina Pedicchio on Exactness and Regularity for Locally Presentable Categories After that, we would like to invite those who arrive here early to visit the Herzog August Library in Wolfenb"uttel with its famous collection of medieval books. Gotthold Ephraim Lessing used to be a librarian there. Braunschweig is located about 60 km East of Hannover and can easily be reached by car or train. The closest airport is in Hannover; the airport bus to the Hannover train station takes about 20 minutes, and the train from there to Braunschweig takes about 40 minutes or less. We will send further information on the location of the seminar, along with details on local travel and accommodation to those who register, at least a week before the meeting. Jiri Adamek J"urgen Koslowski ------------------------------------------------------------------------ Please return to J"urgen Koslowski <koslowj(a)iti.cs.tu-bs.de>, preferably before April 13. Postal address: Institut f"ur Theoretische Informatik TU Braunschweig Postfach 3329 D-38023 Braunschweig Germany I intend to come to the 64th meeting of the PSSL in Braunschweig * I intend to give a talk entitled ..................................... * I intend to visit the Herzog August Library on Friday afternoon * Please reserve accommodation for Thursday/Friday/Saturday/Sunday night(s) Name : Address: Email : Phone : *Delete if inapplicable -- J"urgen Koslowski % If I don't see you no more in this world ITI % I meet you in the next world TU Braunschweig % and don't be late! koslowj(a)iti.cs.tu-bs.de % Jimi Hendrix (Voodoo Child)

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Locales as "topology-free spaces"
by Steve Vickers 21 Feb '97

21 Feb '97

I am making two papers available as Departmental Research Reports: "Topical Categories of Domains" "Localic Completion of Quasimetric Spaces" Both explore the idea of locales (and, indeed, toposes) as "topology-free spaces". The technique is to work not with frames (point-free topologies) but with presentations of them, understood as propositional geometric theories whose models are the points. (But it is normally more convenient to work with equivalent predicate theories.) Then - * the geometric theory already determines an implicit topology on its models; * any construction of models of one theory out of models of another automatically determines a continuous map (or geometric morphism), just so long as the construction is geometric. In effect, a restriction to geometric mathematics removes the need to treat topology explicitly, hence "topology-free spaces". Apparently, explicit topology is needed to correct the over-credulousness of classical reasoning principles, though in practice the geometric constraints often end up forcing one to reintroduce the normal topological arguments in a different guise. The two papers test the applicability of the idea in the two areas of domain theory and quasimetric spaces. Aside from the "topology-free space" aspects, the papers develop some new results: "Topical Categories of Domains" addresses categorical domain theory and replaces the usual classes of objects and morphisms by toposes classifying them. New general results concerning fixpoints of endo-geometric-morphisms of toposes exploit their intrinsically topological nature to give a simple approach to the solution of domain equations. The paper also gives a summary of the constructive theory of Kuratowski finite sets and establishes some limitations to the Cartesian closedness of Sets. "Localic Completion of Quasimetric Spaces" proposes a construction of locales in completion of quasimetric spaces (using ideas of flatness deriving from Lawvere's enriched category account), studies the powerlocales and shows that a limit map from a locale of Cauchy sequences to the completion is triquotient in the sense of Plewe. Paper copies are available from me; electronic copies are expected to be available shortly in the Department of Computing's Research Report series coordinated by Frank Kriwaczek (frk(a)doc.ic.ac.uk) Steve Vickers.

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revised paper available
by koslowj＠iti.cs.tu-bs.de 19 Feb '97

19 Feb '97

Hello, A revised version of my article "A convenient category for games and interaction" is available from my home page http://www.iti.cs.tu-bs.de/TI-INFO/koslowj/koslowski.html It better substantiates my claim of last year's workshop Domains II here in Braunschweig that the composition of games I introduced is orthogonal to the established composition of strategies. The abstract is appended at the end. If you had trouble in the past reaching my home page, we did find a faulty entry in a name server last Fall. If the problems persist, please let me know! -- J"urgen %% Abstract for: A convenient category for games and interaction Guided by the familiar construction of the category rel of relations, we first construct an order-enriched category gam . Objects are sets, and 1-cells are games, viewed as special kinds of trees. The quest for identities for the composition of arbitrary trees naturally suggests alternating trees of a specific orientation. Disjoint union of sets induces a tensor product $\otimes$ and an operation --o on gam that allow us to recover the monoidal closed category of games and strategies of interest in game theory. Since gam does not have enough maps, \ie, left adjoint 1-cells, these operations do not have nice intrinsic descriptions in gam . This leads us to consider games with explicit delay moves. To obtain the ``projection'' maps lacking in gam , we consider the Kleisli-category K induced by the functor _+1 on the category of maps in gam . Then we extend gam as to have K as category of maps. Now a satisfactory intrinsic description of the tensor product exists, which also allows us to express --o in terms of simpler operations. This construction makes clear why $\multimap$, the key to the notion of strategy, cannot be functorial on gam . Nevertheless, the composition of games may be viewed as orthogonal to the familiar composition of strategies in a common framework. -- J"urgen Koslowski % If I don't see you no more in this world ITI % I meet you in the next world TU Braunschweig % and don't be late! koslowj(a)iti.cs.tu-bs.de % Jimi Hendrix (Voodoo Child)

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CSL '97 second announcement and call for papers
by Uffe Henrik Engberg 18 Feb '97

18 Feb '97

CSL '97 Annual Conference of the European Association for Computer Science Logic August 23-29, 1997 7 Aarhus, Denmark Second Announcement and Call for Papers CSL is the annual conference of the European Association for Computer Science Logic (EACSL). The conference is intended for computer scientists whose research activities involve logic, as well as for logicians working on topics significant for computer science. Scientific Program August 23-24, 1997: Tutorials on Games and Logic S. Abramsky (Edinburgh): Game Semantics A. E. Emerson (Austin): Games, 5-calculus, and program verification W. Thomas (Kiel), I. Walukiewicz (Warsaw): Determinacy, the Rabin Tree Theorem and its extensions August 25-29, 1997: Invited Lectures and Contributed Papers The list of invited speakers will include: S. Buss (San Diego), H. Comon (Paris), T. Coquand (Gothenburg), M. Hyland (Cambridge), N. Immerman (Amherst), N. Klarlund (Murray Hill), Y. Moschovakis (Los Angeles), L. Pacholski (Wroclaw). Local Organization and Accommodation BRICS, Department of Computer Science, University of Aarhus. Limited financial support for young researchers is available. Inquiries and applications should be sent to csl97(a)brics.dk. Further information can be found on http://www.brics.dk/CSL97. Submissions Authors are invited to submit a draft or full paper (up to 12 pages) together with a two page abstract. The cover page should include title, authors, and corresponding authors (name, address, phone/fax number, e-mail address). Electronic submissions are encouraged. Submission forms can be obtained from http://www.brics.dk/CSL97/subm.html or by sending an empty message with Subject: submission information to: csl97-subm(a)brics.dk. Alternatively, five hardcopies should be sent to: Prof. Mogens Nielsen, CSL '97 Department of Computer Science University of Aarhus Phone: +45 8942 3260 Ny Munkegade, Bldg. 540 Fax: +45 8942 3255 DK-8000 Aarhus C, Denmark E-mail: csl97(a)brics.dk Deadline of Submission: April 15, 1997 Authors will be notified of acceptance for presentation at the conference by June 15, 1997. A preliminary version of the full paper to be submitted to the Proceedings volume (LNCS Springer-Verlag) should be available at the conference. Authors will be notified of acceptance of their paper by December 15, 1997. Program Committee K. Compton (Ann Arbor), J. Flum (Freiburg), J.-Y. Girard (Paris), F. Honsell (Udine), J. W. Klop (Amsterdam), W. Marek (Lexington), M. Nielsen (Aarhus, Vice-chair), P. Pudlak (Prague), E. Robinson (QMW, London), A. Tarlecki (Warsaw), W. Thomas (Kiel, Chair), I. Walukiewicz (Warsaw) EACSL Board E. Bvrger, D. van Dalen, K. Ambos-Spies, K. Meinke, J.Y. Girard, C. Bvhm, B. Buchberger, Y. Gurevich, L. Pacholski The conference is sponsored by BRICS (Basic Research in Computer Science), a Centre of the Danish National Research Foundation

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query
by James Stasheff 10 Feb '97

10 Feb '97

is there a name for a gadget with stict unit strict inverses but multiplcation not always defined and associativity holds when both a(bc) and (ab)c are defined BUT neither bracketing existing implies the other exists references? thanks .oooO Jim Stasheff jds(a)math.unc.edu (UNC) Math-UNC (919)-962-9607 \ ( Chapel Hill NC FAX:(919)-962-2568 \*) 27599-3250 http://www.math.unc.edu/Faculty/jds May 15 - August 15: 146 Woodland Dr Lansdale PA 19446 (215)822-6707

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weak n-categories
by john baez 06 Feb '97

06 Feb '97

Here is the abstract of a paper that is now available at my website. If printing it out is a problem (see below) I can mail copies to people. - John Baez ---------------------------------------------------------------------- Higher-Dimensional Algebra III: n-Categories and the Algebra of Opetopes John C. Baez and James Dolan We give a definition of weak n-categories based on the theory of operads. We work with operads having an arbitrary set S of types, or `S-operads', and given such an operad O, we denote its set of operations by elt(O). Then for any S-operad O there is an elt(O)-operad O+ whose algebras are S-operads over O. Letting I be the initial operad with a one-element set of types, and defining I(0) = I, I(i+1) = I(i)+, we call the operations of I(n-1) the `n-dimensional opetopes'. Opetopes form a category, and presheaves on this category are called `opetopic sets'. A weak n-category is defined as an opetopic set with certain properties, in a manner reminiscent of Street's simplicial approach to weak omega-categories. In a similar manner, starting from an arbitrary operad O instead of I, we define `n-coherent O-algebras', which are n times categorified analogs of algebras of O. Examples include `monoidal n-categories', `stable n-categories', `virtual n-functors' and `representable n-prestacks'. We also describe how n-coherent O-algebra objects may be defined in any (n+1)-coherent O-algebra. ----------------------------------------------------------------------- The paper is available in Postscript form on the web at http://math.ucr.edu/home/baez/op.ps The paper is 59 pages long, so this file is rather large. A compressed version is available at http://math.ucr.edu/home/baez/op.ps.Z You can download this and then (on most UNIX systems) type uncompress op.ps.Z to get the Postscript file. If you like ftp, you can also get these by anonymous ftp to math.ucr.edu They are in the directory pub/baez as the files op.ps and op.ps.Z

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