September 2000 - Categories - categories.org.au

REMINDER: Submission Deadline for TLCA 01
by Samson Abramsky 30 Sep '00

30 Sep '00

This is a reminder about the submission deadline for: Fifth International Conference on Typed Lambda-Calculi and Applications which will be held in Krakow, Poland, May 2nd-5th, 2001. The deadline is: OCTOBER 9TH 2000. The scientific scope of TLCA is quite broad, and includes topics from proof theory and semantics to types and logical frameworks, and functional and logic programming. The original call-for-papers follows: (see also the home page at http://www.ii.uj.edu.pl/zpi/tlca2001/) ******************************************************** * * TLCA 2001 * * 5th International Conference on * Typed Lambda Calculi and Applications * May 2 -- 5, 2001 * Krakow, Poland * ******************************************************** * CALL FOR PAPERS ******************************************************** The TLCA series of conferences aims at providing a forum for the presentation and discussion of current research in a field which was originally rather restricted, but has now expanded considerably. Typical areas include, but are not limited to: Proof theory: Natural Deduction and Sequent Calculi, Cut elimination and Normalization, Computational interpretations of Classical Logic, Linear Logic and Proof Nets, Bounded systems capturing complexity classes Semantics: Denotational semantics, Operational semantics, Game semantics, Realizability, Categorical models, Logical Relations, Full Completeness Implementation: Abstract machines, Parallel execution, Optimal Reduction Types: Polymorphism, Dependent types, Intersection types, Subtypes Logical Foundations: Logical Frameworks, Pure Type Systems, Proof checking Programming: Foundational aspects of: Functional programming, Proof search and logic programming, Connections between and combinations of functional and logic programming, Type checking, Higher-order rewriting, Higher-order unification and matching Important Dates =============== Deadline for Submissions: October 9, 2000 Notification to Authors: December 18, 2000 Final Versions due: February 1, 2001 The accepted papers will be published as a volume of the Springer Lecture Notes in Computer Science. Information about LNCS can be found at: http://www.springer.de/comp/lncs/index.html Submission Guidelines ===================== Papers should not exceed 15 standard A4 or US quarto pages, and should allow the Programme Committee to assess the merits of the work: in particular, references and comparisons with related work should be included. Submission of material already published or submitted to other conferences with published proceedings is not allowed. If available, e-mail addresses and fax numbers of the authors should be included. Electronic submissions ====================== Electronic submissions are strongly encouraged. A gzipped Postscript version of the paper should be sent as an e-mail message to: tlca01(a)comlab.ox.ac.uk In addition, the following information in ASCII format should be sent to this address in a **separate** e-mail: Title; authors; communicating author's name, address, and e-mail address and fax number if available; abstract of paper. Hard-copy submissions ===================== If electronic submission is not possible, authors may submit five (5) hard copies of the paper by post to the following address: TLCA 2001 (Attention: S. Abramsky) Oxford University Computing Laboratory Wolfson Building Parks Road Oxford OX1 3QD United Kingdom Questions concerning submissions ================================ These should be addressed to the Program Chair, Samson Abramsky: samson(a)dcs.ed.ac.uk Program Committee ================= S. Abramsky (Edinburgh) (chair) P.-L. Curien (Paris) P. Dybjer (Goteborg) T. Ehrhard (Marseille) M. Hasegawa (Kyoto) F. Honsell (Udine) D. Leivant (Bloomington) S. Ronchi della Rocca (Turin) H. Schwichtenberg (Munich) P. Scott (Ottawa) J. Tiuryn (Warsaw) Organizing Committee ==================== M. Zaionc (chair) P. Urzyczyn TLCA 2001 web page ================== http://www.ii.uj.edu.pl/zpi/tlca2001/

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WADT/CoFI 2001: Call for abstracts
by WADT 2001 30 Sep '00

30 Sep '00

WADT/CoFI 2001 15th International Workshop on Algebraic Development Techniques joint with General Workshop of the CoFI WG & CASL Tutorial Genova, Italy 1-3 April 2001 http://www.disi.unige.it/wadt2001/ Aims and Scope ============== The algebraic approach to system specification and development, born as a formal method for abstract data types, encompasses today the formal design of integrated hardware and software systems, new specification frameworks and programming paradigms (such as object-oriented, logic and higher-order functional programming) and a wide range of application areas (including information systems, concurrent and distributed systems). The topics of the workshop include, but are not limited to: - algebraic specification - other approaches to formal specification - specification languages and methods - term rewriting and proof systems - specification development systems (concepts, tools, etc.) The workshop will provide an opportunity to present recent and ongoing work, to meet colleagues, and to discuss new ideas and future trends. The workshop will start with a full day tutorial on CoFI, the Common Framework Initiative for algebraic specification and development of software, see http://www.brics.dk/Projects/CoFI. This tutorial will also be available to people who do not wish to participate in the rest of the workshop. Besides the tutorial, there will be CoFI Task Group meetings and presentation on related topics during the workshop. The workshop will be a satellite event of the European Joint Conferences on Theory and Practice of Software (ETAPS2001). Special deals will be available for participants wishing to attend WADT/CoFI 2001 together with other events of ETAPS. More information on ETAPS is available at http://www.disi.unige.it/etaps2001/ Submissions =========== The scientific programme of the workshop will include up to about 30 presentations of recent results and ongoing research. The presentations will be selected according to originality, significance, and general interest, on the basis of submitted abstracts. The selection committee consists of the WADT Steering Committee together with the local organizers (listed below). The abstracts must be in pdf (or standard postscript) format, up to two pages long in the style for publication in Lecture Notes in Computer Science (see http://www.springer.de/comp/lncs/authors.html) and should be sent by e-mail to wadt2001(a)disi.unige.it. The deadline for submission of abstracts is 10 January, 2001. Abstracts that substantially depart from the required format, style or length may be rejected without consideration. The final versions of the selected abstracts (due by 26 February) will be made available on the workshop web page, and included in a hand-out for the workshop participants. After the workshop, selected authors will be invited to submit full papers for the refereed proceedings, which is expected to be published as a volume of Springer Lecture Notes in Computer Science (http://www.springer.de/comp/lncs/) Location ======== WADT/CoFI 2001 will be held in Genova. Information are also be available on the web at the page http://www.disi.unige.it/wadt2001/ ********************************************************************** ************************** Important Dates *************************** ********************************************************************** * Deadline for abstracts: 10 January, 2001 * * Notification sent to authors: 26 January, 2001 * * Final abstract due: 26 February, 2001 * * Workshop dates: 1-3 April, 2001 * ********************************************************************** WADT Steering Committee ======================= Michel Bidoit (Cachan, France) Hans-Joerg Kreowski (Bremen, Germany) Peter Mosses, chair (Aarhus, Denmark) Fernando Orejas (Barcelona, Spain) Francesco Parisi-Presicce (Rome, Italy) Donald Sannella (Edinburgh, Scotland) Andrzej Tarlecki (Warsaw, Poland) Sponsors ======== The workshop is organized by IFIP WG1.3 (Foundations of System Specification) jointly with CoFI WG. Local Organizers ================ Maura Cerioli Gianna Reggio DISI Universita' degli Studi di Genova Genova - Italy Email: wadt2001(a)disi.unige.it ----------------------------------------------------------------------

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Tech report: Models for Name-Passing Processes
by Luca Cattani 30 Sep '00

30 Sep '00

The following paper by Gian Luca Cattani and Peter Sewell Models for Name-Passing Processes: Interleaving and Causal is available as Technical Report 505 of Cambridge University Computer Laboratory electronically from http://www.cl.cam.ac.uk/users/glc25/modnppictr.html or http://www.cl.cam.ac.uk/users/pes20/ or, in hard copy, by emailing "tech-reports(a)cl.cam.ac.uk". An abstract is attached below. Luca Abstract: We study syntax-free models for name-passing processes. For interleaving semantics, we identify the indexing structure required of an early labelled transition system to support the usual pi-calculus operations, defining Indexed Labelled Transition Systems. For non-interleaving causal semantics we define Indexed Labelled Asynchronus Transition Systems, smoothly generalizing both our interleaving model and the standard Asynchronous Transition Systems model for CCS-like calculi. In each case we relate a denotational semantics to an operational view, for bisimulation and causal bisimulation respectively. We establish completeness properties of, and adjunctions between, categories of the two models. Alternative indexing structures and possible applications are also discussed. These are first steps towards a uniform understanding of the semantics and operations of name-passing calculi.

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Tor in toposes
by Michael Barr 27 Sep '00

27 Sep '00

The category of abelian groups (or modules over a ring object) in a Grothendieck topos does not have any non-zero projectives in general. But free modules are still flat (because the associated sheaf functor preserves sums and monics) and so every module has a flat resolution and this ought to suffice to define Tor. But there are some delicate questions involving well-definedness and functoriality because you cannot lift maps between flats. Does anyone know if this has been published anywhere?

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PhD & postdoc positions available
by Bart Jacobs 25 Sep '00

25 Sep '00

[Apologies for multiple copies.] Several PhD and postdoc positions are available in the area of formal methods for object-oriented languages, at the University of Nijmegen, The Netherlands. The emphasis lies on using proof tools (esp. PVS) for Java(Card) program verification. More information at the URL: http://www.cs.kun.nl/~bart/LOOP/vacancies.html Best regards, Bart Jacobs.

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characterisation of nerve of omega-categories
by Philippe Gaucher 23 Sep '00

23 Sep '00

Dear all, I don't remember where I could find a characterization for a simplicial set to be the simplicial nerve of some strict globular omega-category ? I think that the characterization is that the simplicial set must be given with a structure of thin elements satisfying some axioms like the filling of horners and thin horners. Could you send me a reference please ? Thank you in advance. pg.

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Conference: New programs ... 13-14/11/00
by Giuseppe Longo 21 Sep '00

21 Sep '00

[Note from moderator: this is a plain ascii version of the earlier post, thanks to the poster for providing this.] "New programs and open problems in the foundation of mathematics and of its applications, in year 2000" November 13 and 14, 2000 Ecole Normale Superieure, 45, rue d'Ulm, 75005 Paris Salle Dussane Monday, November 13: 14h : J.-Y. Girard (CNRS, Marseille): "Locus solum" Respondent: P.-L. Curien (CNRS - Univ. Paris VII) 15h 30 : A. Macintyre (Univ. Edinburgh): "Prospects in logic" Respondent: A. Marcja (Univ. Firenze) 17h : PAUSE. 17h 15 : W. Lawvere (SUNY, Buffalo): "Dialectical foundations of, by, and for mathematics" Respondent: I. Moerdijk (Univ. Utrecht) Tuesday, November 14: 9h 30 : R. Milner (Univ. Cambridge): "The flux of computation" Respondent: G. Berry (Ecole des Mines, Sophia-Antipolis) 11h : G. Parisi (Univ. Roma I): "Six spaces looking for a geometer" Respondent: J.-P. Nadal (CNRS-ENS, Paris) Tuesday afternoon: 14h 30 : A. Connes (College de France, Paris): "Non-commutative Geometry" Respondent: C. Soule (IHES, Paris); 16h : Panel discussion : "Geometric Structures in Logic, Physics and Computing" with the invitees and the members of the working group "Geometrie et Cognition" (G. Longo, CNRS-ENS, chair) ------------------ The Conference is one of the activites promoted by the "Atelier de Recherche" Geometrie et Cognition ( http://www.dmi.ens.fr/users/longo/geocogni.html ) financed by the french Ministry of Research, and it is partly supported also by the Laboratoire d'Informatique de l'ENS (LIENS, CNRS). The Conference is open to public (no attendance fees) and the organizers can provide no help to attendees (a list of hotels may be found in : http://www.dmi.ens.fr/users/longo/GeoCo-fold/hotels.html ). http://www.dmi.ens.fr/users/longo/

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yetter&supernishimura
by edubuc＠dm.uba.ar 20 Sep '00

20 Sep '00

i quote from yetter's message: "Does anyone have a full citation to the Nishimura paper which Dubuc justly criticizes for misattributing his construction? I am interested because the title, and lack of care with citations, suggest the possibility that Nishimura is simply reproving results from my paper D.N. Yetter, "Models for Synthetic Supergeometry", Cahier de Top. et Geom. Diff. Cat. 29 (2) (1988) 87-108." Nishimura's paper is titled "Supersmooth Topoi" (I have a only a preprint) It is a well referenced paper. In this paper Nishimura knows and comments on Yetter's (1988). It is actually doing a different thing. He uses my (with Taubin) construction with the notion of analytic ring (1983), which is not to be found in [M-R] monograph. This notion is algebraic but in the sense of a category with finite limits, not in the sense of a category with finite products. (quotients are not suryective to mention a difference) just to clarify my letter, i quote again Yetter above: "Dubuc justly criticizes for misattributing his construction?" Well, Nishimura is using as a reference for my construction the [M-R] monograph, and it is not at fault as I said. The problem is, that it sounds ambigous because a whole situation I described in my letter I quote now again from the [M-R] monograph two references concerning specifically my work, which I found they reveal a lot: "Although this general notion of C-infinity ring does not occur as such in classical analysis and differential geometry, the main examples do ... Given the role of these examples of C-infinity rings in the classical literature, it is not surprising that although the statements of several of the results in this chapter seem new, most of their proofs are either known or easily derivable from known ones". "As far as terminology is concerned, we have tried to avoid descriptions of the type "the Moerdijk envelop of the Reyes topos", in favor of more informative ones" well ... eduardo dubuc

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models of SDG
by edubuc＠dm.uba.ar 20 Sep '00

20 Sep '00

GERM DETERMINED IDEALS AND WELL ADAPTED MODELS OF SDG I write this note because I feel it is time to let know explicitly to the category theory community the following situation, and to make a request. In a recent paper on SDG "Super smooth topoi, by H. Nishimura" one can read the following: "Therefore we must build our model theory of Synthetic Supergeometry not directly after the standard manner of Moerdijk & Reyes [1991] [*] but after the manner of Dubuc-Taubin [1983]". Now, this "standard manner" of building models was developed by Dubuc and not by Moerdijk-Reyes. (in [1983] I developed also the analytic model, which does not correspond to an algebraic theory in the Lawvere sense, and can not be done as the differential models which correspond to C-infinity rings). [*][M-R] "Models of Smooth infinitesimal Analysis", Moerdijk and Reyes, Springer Verlag 1991. Of course, I understand that when a monograph is available, the proper reference is that, and not the original papers. But, phrases as the one quoted above are ambiguous, and at fault is not Nishimura. I shall resume the history of the subject: In a series of papers and many lectures given specially in Montreal, Sydney, Oberwolfach and elsewhere I created and started the developement of the subject of models of SDG adapted (or well adapted as I call them) for the applications to classical differential geometry. [1] Sur les Modeles de la Geometrie Differentielle Sinthetyque, "Cahiers de Topologie et Geometrie Differentielle" Vol. XX-3 (1979). [2] Schemas C-inf (amplified version of [3], with detailed proofs and many examples), "Prepublications de la Universite de Montreal" 80-81 edited by G. Reyes (1980). [3] C-inf Schemes, "American Journal of Mathematics", John Hopkins University, Vol. 103-4 (1981). [4] Open Covers and Infinitary Operations in C-inf-rings, "Cahiers de Topologie et Geometrie Differentielle" Vol. XXII-3 (1981). [5] Archimedian Local C-inf-rings and Models of SDG (with Marta Bunge), "Cahiers de Topologie et Geometrie Differentielle" Vol. XXVII-3 (1986). [6] Germ representability and Local integration of vector fields in a well adapted model of SDG, "Journal of Pure and Applied Algebra" Vol. 64 (1990). A) I introduced the notion of well adapted models and constructed the first ones. B) I started a systematic study of C-infinity rings as such. Of course, they were already there, but nothing had been done with them. I had to state and prove even such simple facts as that the algebraic quotient of a C-infinity ring by an R-algebra ideal had a canonical structure of C-infinity ring, and was then the quotient in this category. I introduced the notion of Germ Determined Ideal (or ideal of local nature), which was, as such, nowhere to be found in the literature, and stated and proved their basic properties. This, I think, is the most important concept in the subject. It is the basic definition to start to build upon. It is just the right concept needed. Among other things, I first proved it contains all finitely generated ideals, and defines the largest possible class of C-infinity rings consistent with the nullestelentsatz. This means that the ring can be seen as the ring of global sections of a C-infinity Scheme. The notion of germ determined ideal also determines the right notion of C-infinity local ring (notice that I do not say local C-infinity ring), that I then developed. I also developed the relative C-infinity version of inverting elements universally, and proved that the ring of C-infinity functions defined in an open set U inverts universally a function which is non-zero exactly on U (every Euclidean open is C-infinity Zariski). Etc, etc, all the basic structure of the C-infinity relative version of algebraic geometry. Now, [M-R] write "Although this general notion of C-infinity ring does not occur as such in classical analysis and differential geometry, the main examples do ... Given the role of these examples of C-infinity rings in the classical literature, it is not surprising that although the statements of several of the results in this chapter seem new, most of their proofs are either known or easily derivable from known ones". This is, at the least, misleading, and can also be applied to many important concepts in mathematics. Of course, when the new concepts are introduced, the examples are already there, and the proof of the basic properties is easy. [M-R] ignore the fact that the important thing is to identify explicitly the concept, and to identify the right statements. And this does not come easily. And I repeat, even if C-infinity rings may have been there, the concept of germ determined ideal was not, and derived concepts and the statments of their basic essential properties could not even be there. C) With this in hand, I introduced the Topos G of sheaves for the open covering topology on the dual of the category of C-infinity rings presented by a germ determined ideal, and proved all the basic important properties, which many times are the correct relative C-infinity versions of corresponding properties in algebraic geometry. This topos is the best known model in order to do applications of SDG to classical differential geometry, and as such, it is the most utilized in practice. Many early workers in the subject (J. Penon, O. Bruno, F. Gago, Yetter, among others) called this topos "The Dubuc Topos". Even Moerdijk and Reyes did so in some preprints, although they changed this in the published version. Now, [M-R] write "As far as terminology is concerned, we have tried to avoid descriptions of the type "the Moerdijk envelop of the Reyes topos", in favor of more informative ones". But the true fact was that the only name that was involved was "Dubuc", since no other new name was being utilized at the time (of course, things as Kock-Lawvere Axiom or Weil algebras were not aimed by this philosophy, and "Moerdijk envelop of the Reyes topos" was an invention). D) I should mention here that I do not ignore the fact that my work is acknowledged and referenced in the monograph [M-R], and that this can be proved in a court of Law. The matter is much more subtle, and nobody can deny the evidence of the following consequence of this maneuvering: A consequence of this maneuvering is that my name, as time passes, and as young people appear, is less and less associated with a subject that I created and developed in large part. Namely, models of SDG adapted to classical differential geometry. People talk as if the well adapted models were always there, or start referring to them in a way that may lead inexperienced (in the subject) readers to believe that these constructions are "M-R way of doing models", as I quoted at the beginning of this note. This is what it is actually happening, and no arguing can deny it. E) This does not do justice to my work, and does not corresponds to the true history of the subject. As an starting point to remedy it, I request all workers that need to use the topos G, to refer to it as "Dubuc Topos". After all, it is a long tradition in mathematics to associate proper names to important concepts or constructions when it is justified, as I believe it is the case here. Eduardo J. Dubuc Buenos Aires, September 2000.

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Dave Harrison
by Michael Barr 20 Sep '00

20 Sep '00

I have just received from Ann Harrison the sad news that Dave died last Dec. 21. I suspect that most of the younger practitioners of category theory are not aware of Dave's contributions to the subject. Not in the sense of having actively worked on it, but of having encouraged it in the very early days. When he came to Penn he taught a course in homological algebra that used categories extensively. In point of fact, I had never heard of a category before taking that course. Then he was one of the main organizers of the La Jolla conference in 1965 that was the first ever major international conference in categories. (The first conference that I am aware of was the midwest category meeting that Saunders Mac Lane organized in April (I think) of the same year, a few months earlier. But the participants consisted only of a handful of people from Urbana and Chicago.) For anyone who wishes to write Ann, her address is 12 Striper Lane, Chatham, MA 02633. Michael

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