Date: Tue, 5 Apr 1994 11:28:25 +0500 (GMT+4:00) Subject: Re: local homeomorphisms Date: Tue, 5 Apr 94 08:53:53 EDT From: Peter Freyd In my last posting I had written: Peter Selinger, a student here at Penn, observes that the category of topological spaces and local homeomorphisms fails to be complete only because it fails to have a terminator. That is, every _non-empty_ small diagram has a limit. Who knows a reference for this? What I didn't realize is that he was correcting an error in "Categories, Allegories." On page 50 (1.461) we wrote that the category in question fails to have binary products. Wrong. I'm concluding that this was not known before. It's a nice example of a product that's very much not preserved by the forgetful functor. The product of the space of rational numbers with itself is uncountably large. (And for every infinite cardinal there's a space whose product with itself has the next power-cardinal as its size.) Date: Tue, 5 Apr 1994 11:27:34 +0500 (GMT+4:00) Subject: PSSL Date: Tue, 5 Apr 94 12:56:14 BST From: Lorraine Edgar PERIPATETIC SEMINAR ON SHEAVES AND LOGIC 55th Meeting---Preliminary Announcement The 55th meeting of the seminar will be held at the University of Edinburgh's Computer Science Department over the weekend of 28-29 May 1994. As usual, we welcome talks near the triple point linking category theory, geometry and logic. We will send further information on the location of the seminar, along with local travel details, on receipt of registration forms. A list of guest houses/hotels available from lme@dcs.ed.ac.uk on request. It is easiest for us if UK participants make their own arrangements for accommodation, but we will be happy to try and help anyone who has any difficulties. Edinburgh, as one of the world's prettiest cities, is a tourist haven in summer, so it would be advisable to secure accommodation well in advance. John Power Marcelo Fiore Lorraine Edgar ------------------------------------------------------------------------------- Please return to Lorraine Edgar, Dept of Computer Science, University of Edinburgh, The King's Buildings, Edinburgh EH9 3JZ. I intend to come to the 55th meeting of the PSSL. * I intend to give a talk entitled * Please reserve accommodation for Friday/Saturday/Sunday night(s). Name Address Email Tel No Fax No (* Delete if inapplicable) Date: Wed, 6 Apr 1994 16:11:10 +0500 (GMT+4:00) Subject: Re: local homeomorphisms Date: Wed, 6 Apr 1994 13:33:00 -0400 (EDT) From: D_FELDMAN@UNHH.UNH.EDU Allow me please to muse on Peter Freyd's two postings concerning observations of Peter Selinger and himself on the category of topological spaces and local homeomorphisms. Is the product of X_1 and X_2 identical to the etale space of the sheaf that associates to an open set U of X_1 all the local homeomorphisms from U to X_2? Of course if this is right, then the roles of X_1 and X_2 can be reversed. Indeed, both etale spaces consist of germs of homeomorphisms between X_1 and X_2. The advantage of taking this point of view, besides that fact that perhaps the sheaf is easier to thing about than its etale space, is that it suggests persuing a more general construction. In a sense that I don't yet know how to make precise, X_1 x X_2 is a schizophrenic object because it lives in both toposes of sheaves, over X_1 and X_2, and it is in some sense the universal such schizophrenic object. So my question is, can this be made precise so that one could ask for a universal schizophrenic given any two toposes. My guess is that the analogous construction given the topos of M_1-sets and M_2-sets, M_1 and M_2 being monoids, would be to construct the free product M_1 * M_2, which also lives naturally in both categories. Moreover all M_1 * M_2-sets live in both categories, just as all sheaves over X_1 x X_2 induce sheaves over X_1 and over X_2. I don't know much about toposes. Is there already some well-known construction that fits the bill? David Feldman University of New Hampshire Date: Wed, 6 Apr 1994 16:09:43 +0500 (GMT+4:00) Subject: Re: local homeomorphisms Date: Wed, 6 Apr 1994 3:21:43 -0400 (EDT) From: D_FELDMAN@UNHH.UNH.EDU Would the category of topological spaces and partial local homeomorphisms be complete? I mean, partial maps which are local homeomorphism on their locus of definition. David Date: Wed, 6 Apr 1994 16:15:05 +0500 (GMT+4:00) Subject: Workshop on foundational methods in Computer Science Date: Thu, 31 Mar 94 14:52:15 -0800 From: John MacDonald Preliminary Announcement: Third Annual Workshop on Foundational Methods in Computer Science A workshop on applications of categories in compouter science Dates: June 3-5, 1994 Location: University of British Columbia, Vancouver, B. C. Overview: This will be the third year of the workshop on foundational methods in computer science. It is an "informal, even casual", workshop bringing together mathematicians and computer scientists with an interest in category theory and its applications to computer science. The workshop will have approximately the same format as last year, with a one day tutorial on June 3 and short research presentations on June 4 and 5. There will not be a formal proceedings. Guests: We are still in the process of contacting distinguished visitors and guests. Participation: People wishing to participate should send me email at fmcs@math.ubc.ca. We hope to encourage the participation of researchers at all levels in this workshop, including graduate students. Fees: I have made arrangements for accomodations on the UBC campus. The budget has not been completed so I don't yet have a registration fee calculated. I hope to keep the fees to an absolute minimum. An application for dormitory accomodation as well as the amount of registration fee will come in a further communication. Email address: fmcs@math.ubc.ca -------------------------------------------------------------------- John MacDonald, Department of Mathematics, UBC, Vancouver, B.C., Canada V6T 1Y4 johnm@math.ubc.ca Phone: (604) 822-3627 --------------------------------------------------------------------- Art Stone stone@math.ubc.ca Phone: (604) 421-3054 Date: Wed, 6 Apr 1994 21:57:30 +0500 (GMT+4:00) Subject: LICS'94 Program and Registration Date: Wed, 6 Apr 94 19:41 EDT From: Amy Felty [This announcement is being sent to email lists. Our apologies for multiple copies.] LOGIC IN COMPUTER SCIENCE (LICS) ******************************** Ninth Annual IEEE Symposium July 3-7, 1994, Paris, France ADVANCE REGISTRATION AND PROGRAM INFORMATION ============================================ [This information is available on the world-wide web at http://www.research.att.com/lics/ Postscript, dvi, latex and plain text versions of the conference brochure are available via anonymous ftp from research.att.com in directory /dist/lics.] CONFERENCE OFFICE. ================= Please address registration form and inquiries to LICS'94 Secretariat Claudie Thenault INRIA-Rocquencourt Relations Exterieures Domaine de Voluceau BP 105 78153 Le Chesnay Cedex FRANCE Phone: 33 (1) 39 63 56 75 Fax: 33 (1) 39 63 56 38 E-mail: symposia@inria.fr REGISTRATION ============ The registration form should be sent to the conference office. Registration without payment (or purchase order) enclosed will not be considered. For early registration, payment must be received by June 5. Fees will be returned in full for any written cancellation received before June 24. No refund will be made after this date. A table of registration fees can be found on the registration form. The member rate applies to members of ACM, IEEE, EATCS and INRIA, members of the organizing and program committees and authors of accepted papers. The student rate applies to full time students; a copy of the registrant's 1993-94 student card should be included with the registration form. The registration fee includes conference participation, a copy of the proceedings, coffee breaks and an invitation to the welcome reception. There is a separate charge for the banquet. Payment must be in French currency, and can be made by bank cheque, postal cheque, or foreign draft made payable to "Agent Comptable de l'INRIA", by bank transfer to Tresorerie Generale des Yvelines, Versailles, account number 10071-78000-00044009 15389, by postal transfer to CCP Paris---30041-00001-09099 45 B 020-31, or by institutional purchase order. We have applied for permission to allow registration by credit card, and hope to have confirmation of this possibility by May 1. Participants wishing to use this facility should contact our office at that time, preferably by email addressed to symposia@inria.fr. Bank transfers should specify registrant's name and "Conference reference LICS94". ACCOMMODATION ============= Reservations can be made through the Wagonlit Travel Agency. The accommodation form should be sent with deposit before June 1 to: Wagonlit Travel Departement Congres & Evenements 50 Rue de Londres 75008 Paris FRANCE Tel: 33 (1) 44 90 33 10 Fax: 33 (1) 44 90 33 15 There are two categories of hotels available, as well as inexpensive student lodging (no age limit) in an international center in Clichy (north Paris). Paris is very popular in the summer, so reservations should be made as soon as possible. A deposit is compulsory for hotel reservations, and student lodging must be entirely prepaid. Payment must be in French currency, and can be made by bank cheque, Eurocheque, or foreign draft made payable to "Wagonlit Travel", by bank transfer to the account 00021935201/61 B.N.P. Paris Saint Lazare, bank code 30004, branch code 0819, "Wagonlit Travel---code comptable 04/670", or by credit card. Hotel deposits will be forwarded to the hotel less 60FF for reservation fees. The participant's bank charges must be added to the amount transferred. For cancellations made before June 1, payments will be refunded less 60FF for fees; no refunds will be made after June 1. LOCATION ======== The Conference is being hosted by the Conservatoire National des Arts et Metiers (CNAM) and will be part of its Bicentennial celebration. CNAM is a well-known engineering school where professionals are taught by professionals. It houses the famous Musee National Des Arts et Techniques, and is located at 292 Rue Saint Martin in the old center of Paris, on the right bank of the river Seine. It is walking distance from Les Halles, the Centre National d'Art et de Culture Georges-Pompidou (Beaubourg), the Hotel de Ville (City Hall) and the cathedral Notre-Dame de Paris. The nearest Metro station is Arts et Metiers. Paris normally enjoys pleasant summer weather in early July. Days are warm, but nights may be cool. For general information on Paris, contact the Paris Tourist Information Office, 127 Champs Elysees, 75008 Paris, phone number 33 (1) 49 52 53 54. RECEPTIONS ========== A Welcome Reception will be held on Sunday evening (17:00-19:00) in a gallery of CNAM. The Conference Banquet will be held in the palace housing the Senate, the upper chamber of the French Parliament. The palace was built in the beginning of the 17th century for Marie de Medicis, widow of King Henry IV. It is located in the well-known Jardins du Luxembourg. To reserve a place at the banquet, the appropriate column on the registration form must be marked; a banquet reservation on site will not be possible. LOCAL ARRANGEMENTS ================== Lunches are at the participants' own expense. Participants may eat in cafes and restaurants in CNAM's vicinity. Telephone messages will be delivered to participants during breaks. Access to email will be possible from CNAM. The organizers cannot be held liable to conference participants for injury, damage or loss of their personal property. It is suggested that participants make their own insurance arrangements. REGISTRATION DESK ================= A registration and information desk located at the conference site will operate on Sunday, July 3, from 15:00 to 18:00, and on the remaining conference days from 8:00 to 18:00. TRAVEL ====== Paris has two airports, Roissy-Charles de Gaulle, 30km north of Paris, and Orly, 20km south of Paris. A frequent Air France bus service goes from Roissy to Place Charles de Gaulle-Etoile or Porte Maillot in central Paris (the cost is about 48FF); from Orly the bus goes to Invalides and stops on demand at Montparnasse (32FF). There is also train service. From Roissy, the RER B line goes to Gare du Nord or Chatelet; from Orly, the Orlyval goes to Antony where there is a connection to the RER B (32FF). A taxi from Orly to central Paris costs about 150FF; from Roissy, 200FF. The Metro offers a convenient way to get around the city. Each trip (with unlimited transfers) costs one ticket. Tickets can be bought individually, but a carnet of 10 is more practical. RER lines to the suburbs connect with the Metro and cost more. Both Metro and RER tickets can be purchased from ticket booths or machines. A 40-45% discount may be obtained from AIR INTER for French domestic blue and white flights, depending on the days of departure. A voucher can be requested on the registration form. Participants requiring a visa for entry into France are strongly advised to make their application in their home countries at least two months prior to departure date. LICS'94 REGISTRATION FORM ************************* Last Name __________________________________________________ First Name _________________________________________________ Affiliation ________________________________________________ Street Address _____________________________________________ _______________________________________________________ City _______________________________________________________ State/Zip __________________________________________________ Country ____________________________________________________ Phone(s) ___________________________________________________ Fax ________________________________________________________ E-mail _____________________________________________________ REGISTRATION RATES. The fees below are in French currency and include 18.6% VAT. Please circle the applicable fees. through June 5 from June 6 Regular 2200 2600 Member 1700 2100 Student 1000 1200 Banquet 300 300 Total Fee ___________________________________________________ Rate justification __________________________________________ Full-time student at ________________________________________ I need an AIR INTER discount form: Yes / No Payment (circle one): Cheque (Bank/Foreign Draft) / Purchase Order / Bank Transfer (include copy) LICS'94 ACCOMMODATION FORM ************************** to be returned before Jun 1 Last Name __________________________________________________ First Name _________________________________________________ Company ____________________________________________________ Street Address _____________________________________________ _______________________________________________________ City _______________________________________________________ State/Zip __________________________________________________ Country ____________________________________________________ Phone(s) ___________________________________________________ Fax ________________________________________________________ 1A. HOTEL. Please reserve: *...twin bed room shared by 2 persons *...single room in a hotel of ________ stars, for ________ nights, from _________________ to _________________(a.m.). Average rates in French currency, per room and per night, room only, taxes and service included: Category Single/Twin Deposit 2** 385/500 460 3*** 550/700 760 1B. YOUTH HOSTEL. Please reserve: *...bed in a twin bed room, bathroom and toilets outside the room, compulsory stay of 4 nights (July 3 to 7, 1994), continental breakfast included, full prepayment compulsory, fixed rate per person 4 nights: 600FF. 2. PAYMENT. Deposit/prepayment of ____________ FF Circle one: Visa / Eurocard / Mastercard / Cheque (Bank/Euro/Foreign Draft) / Bank Transfer (include copy) Credit card # __________________________ Exp. __________ Signature _____________________________ Date ___________ CONFERENCE PROGRAM ****************** SUNDAY, July 3 ============== REGISTRATION (15:00-18:00) WELCOME RECEPTION (17:00-19:00) MONDAY, July 4 ============== REGISTRATION (8:00-9:00) OPENING ADDRESSES (9:00-9:25) INVITED LECTURE I (9:25-10:25) Chair: Robert Constable (Cornell) Rod Burstall (Edinburgh), Lambda-terms, proofs and refinement SESSION 1: FINITE MODEL THEORY (10:50-12:30) Chair: Daniel Leivant (Indiana) 10:50 McColm's Conjecture, Yuri Gurevich (Michigan), Neil Immerman (U Mass) & Saharon Shelah (Hebrew U & Rutgers) 11:15 The expressive power of finitely many generalized quantifiers, Anuj Dawar (Swansea) & Lauri Hella (Helsinki) 11:40 Generalized quantifiers for simple properties, Martin Otto (RWTH Aachen) 12:05 How to define a linear order on finite models, Lauri Hella (Helsinki), Phokion Kolaitis (UC Santa Cruz), & Kerkk Luosto (Helsinki) LUNCH (12:30-14:00) SESSION 2: CONCURRENCY (14:00-15:15) Chair: Vaughan Pratt (Stanford) 14:00 Finitary fairness, Rajeev Alur (Bell Labs) & Thomas Henzinger (Cornell) 14:25 Bisimulation is not (first-order) equationally axiomatisable, Peter Sewell (Edinburgh) 14:50 Foundations of timed concurrent constraint programming, Vijay Saraswat (Xerox PARC), Radha Jagadeesan (Loyola) & Vineet Gupta (Stanford) SESSION 3: SEMANTICS I (15:40-16:55) Chair: Achim Jung (Darmstadt) 15:40 A fully abstract semantics for concurrent graph reduction, Alan Jeffrey (Sussex) 16:05 An axiomatization of computationally adequate domain-theoretic models of FPC, Marcelo Fiore & Gordon Plotkin (Edinburgh) 16:30 On strong stability and higher-order sequentiality, Loic Colson & Thomas Ehrhard (Marne-la-Vallee) SESSION 4: DOMAIN THEORY (17:10-18:00) Chair: Carl Gunter (U Penn) 17:10 Linear types, approximation and topology, Michael Huth, Achim Jung & Klaus Keimel (Darmstadt) 17:35 Domain theory and integration, Abbas Edalat (Imperial Coll.) BUSINESS MEETING (20:00) TUESDAY, July 5 =============== TUTORIAL I (8:30-9:45) Chair: Moshe Vardi (Rice) Ed Clarke (CMU), Model Checking SESSION 5: CONSTRAINTS (10:00-10:50) Chair: Harald Ganzinger (MPI Saarbrucken) 10:00 Negative set constraints with equality: an easy proof of decidability, Witold Charatonik (Wroclaw) & Leszek Pacholski (Polish Academy of Sciences) 10:25 Systems of set constraints with negative constraints are NEXPTIME-complete, Kjartan Stefansson (Cornell) SESSION 6: MODAL AND TEMPORAL LOGICS I (11:15-12:30) Chair: Dexter Kozen (Cornell) 11:15 A compositional proof system for the modal mu-calculus, Hendrik Reif Andersen (TU Denmark), Colin Stirling (Edinburgh) & Glynn Winskel (Aarhus) 11:40 On the parallel complexity of model-checking in the modal mu-calculus, Shipei Zhang, Oleg Sokolsky & Scott Smolka (SUNY Stony Brook) 12:05 Complexity transfer for modal logic, Edith Hemaspaandra (Le Moyne) LUNCH (12:30-14:00) SESSION 7: TYPES I (14:00-15:15) Chair: Paris Kanellakis (Brown) 14:00 Typability and type-checking in the second-order lambda-calculus are equivalent and undecidable, J.B. Wells (Boston U) 14:25 Efficient inference of object types, Jens Palsberg (Northeastern) 14:50 Type inference and extensionality, Adolfo Piperno (Roma) & Simona Ronchi della Rocca (Torino) SESSION 8: CONSTRUCTIVE MATHEMATICS (15:40-16:55) Chair: Daniel Leivant (Indiana) 15:40 A groupoid model refutes uniqueness of identity types, Martin Hofmann (Edinburgh) & Thomas Streicher (LMU Muenchen) 16:05 A non-elementary speed-up in proof length by structural clause form transformation, Matthias Baaz, Christian Fermueller & Alexander Leitsch (TU Wien) 16:30 Upper and lower bounds for tree-like cutting planes proofs, Russell Impagliazzo (UC San Diego), Toniann Pitassi (UC San Diego) & Alasdair Urquhart (Toronto) SESSION 9: COMPLEXITY AND DATABASES (17:10-18:00) Chair: David McAllester (MIT) 17:10 The power of reflective relational machines, Serge Abiteboul (INRIA), Christos Papadimitriou (UC San Diego) & Victor Vianu (UC San Diego) 17:35 A syntactic characterization of NP-completeness, J. Antonio Medina & Neil Immerman (U Mass) EVENING LECTURE (19:30-20:30) Chair: Jean-Pierre Jouannaud (Paris Sud & CNRS) Corrado Boehm (Roma), An algebraic view of the lambda-calculus WEDNESDAY, July 6 ================= TUTORIAL II (8:30-9:45) Chair: Samson Abramsky (Imperial Coll.) Gerard Berry (CMA), The semantics of synchronous concurrent languages SESSION 10: LOGIC PROGRAMMING (10:00-10:50) Chair: Krzysztof Apt (CWI) 10:00 The declarative semantics of the Prolog selection rule, Robert Staerk (U Muenchen) 10:25 Semantics of meta-logic in an algebra of programs, Antonio Brogi & Franco Turini (Pisa) SESSION 11: LINEAR LOGIC (11:15-12:30) Chair: Samson Abramsky (Imperial Coll.) 11:15 A multiple-conclusion meta-logic, Dale Miller (U Penn) 11:40 Proof search in first-order linear logic and other cut-free sequent calculi, Patrick Lincoln & N. Shankar (SRI) 12:05 Linear logic, totality and full completeness, Ralph Loader (Oxford) LUNCH (12:30-14:00) SESSION 12: TYPES II (14:00-15:15) Chair: Frank Pfenning (CMU) 14:00 The emptiness problem for intersection types, Pawel Urzyczyn (Warsaw) 14:25 Subtyping and parametricity, Gordon Plotkin (Edinburgh), Martin Abadi (DEC SRC) & Luca Cardelli (DEC SRC) 14:50 On the Church-Rosser property for expressive type systems and its consequences for their metatheoretic study, Herman Geuvers (Nijmegen) & Benjamin Werner (Cornell & INRIA) SESSION 13: SEMANTICS II (15:40-16:55) Chair: Prakash Panangaden (McGill) 15:40 A semantics of object types, Martin Abadi & Luca Cardelli (DEC SRC) 16:05 Passivity and independence, Uday Reddy (Illinois) 16:30 A general semantics for evaluation logic, Eugenio Moggi (Genova) SESSION 14: CATEGORY THEORY (17:10-18:00) Chair: Glynn Winskel (Aarhus) 17:10 Reflexive graphs and parametric polymorphism, Edmund Robinson (Sussex) & Giuseppe Rosolini (Genova) 17:35 Categories, allegories and circuit design, Carolyn Brown (Sussex) & Graham Hutton (Chalmers) BANQUET THURSDAY, July 7 ================ INVITED LECTURE II (9:00-10:00) Chair: Gerard Huet (INRIA) Henk Barendregt (Nijmegen), Results and problems related to proof-checking SESSION 15: REWRITING (10:00-10:50) Chair: Jean-Pierre Jouannaud (Paris Sud & CNRS) 10:00 Rewrite techniques for transitive relations, Leo Bachmair & Harald Ganzinger, (Max-Planck-Institut) 10:25 Normalised rewriting and normalised completion, Claude Marche (CNRS & INRIA) SESSION 16: LAMBDA-CALCULUS (11:15-12:30) Chair: Jean-Jacques Levy (INRIA) 11:15 Modularity of strong normalization and confluence in the algebraic lambda-cube, Franco Barbanera (Torino), Maribel Fernandez (Paris Sud & CNRS), & Herman Geuvers (Nijmegen) 11:40 Cyclic lambda graph rewriting Zena Ariola (U Oregon) & Jan Willem Klop (CWI) 12:05 Paths in the lambda-calculus, Andrea Asperti (Bologna), Vincent Danos (CNRS & Paris 7), Cosimo Laneve (INRIA & CMA), & Laurent Regnier (CNRS) LUNCH (12:30-14:00) SESSION 17: MODAL AND TEMPORAL LOGIC II (14:00-15:15) Chair: Colin Stirling (Edinburgh) 14:00 A trace based extension of linear time temporal logic, P.S. Thiagarajan (SPIC Madras) 14:25 Axioms for knowledge and time in distributed systems with perfect recall, Ron van der Meyden (NTT Tokyo) 14:50 Compositional verification of real-time systems, Edward Chang (Stanford), Zohar Manna (Stanford), & Amir Pnueli (Weizmann Institute) SESSION 18: LOGIC IN ARTIFICIAL INTELLIGENCE (15:40-16:55) Chair: Peter Schroeder-Heister (Tuebingen) 15:40 Logical bilattices and inconsistent data, Ofer Arieli & Arnon Avron (Tel Aviv) 16:05 A modal logic for subjective default reasoning, Shai Ben-David & Rachel Ben-Eliyahu (Technion) 16:30 Language completeness of the Lambek calculus, Mati Pentus (Moscow State) SESSION 19: AUTOMATED DEDUCTION} (17:10-18:00) Chair: Gerard Huet (INRIA) 17:10 Rigid E-unifiability is NEXPTIME-complete, Jean Goubault (Bull) 17:35 Higher-order narrowing, Christian Prehofer (TU Muenchen) END OF CONFERENCE CONFERENCE ORGANIZATION *********************** LICS General Chair: Robert L. Constable 1994 Conference Co-chairs: Gerard Huet & Jean-Pierre Jouannaud 1994 Program Chair: Samson Abramsky Publicity Co-chairs: Amy Felty & Douglas Howe 1994 Local Arrangements: A. Theis-Viemont & C. Thenault PROGRAM COMMITTEE: ================== S. Abramsky, K. Apt, H. Ganzinger, C. Gunter, A. Jung, P. Kannelakis, D. Kozen, D. Leivant, J.-J. Levy, D. McAllester, P. Panangaden, F. Pfenning, V. Pratt, P. Schroeder-Heister, C. Stirling, G. Winskel. ORGANIZING COMMITTEE: ===================== M. Abadi, S. Abramsky, S. Artemov, A. Borodin, A. Bundy, S. Buss, E. Clarke, R. Constable (Chair), A. Felty, U. Goltz, Y. Gurevich, S. Hayashi, D. Howe, G. Huet, J.-P. Jouannaud, D. Kapur, C. Kirchner, P. Kolaitis, R. Kosaraju, D. Kozen, D. Leivant, A.R. Meyer, D. Miller, J. Mitchell, Y. Moschovakis, M. Okada, P. Panangaden, A. Pitts, G. Plotkin, J. Remmel, S. Ronchi della Rocca, G. Rozenberg, A. Scedrov, D. Scott, J. Tiuryn, M.Y. Vardi. Date: Thu, 7 Apr 1994 15:37:53 +0500 (GMT+4:00) Subject: ftp papers Date: Thu, 7 Apr 1994 07:52:04 -0400 From: Jim Otto ~ftp/pub/otto/README One can get here by ftp triples.math.mcgill.ca cd pub cd otto Currently here is compressed postscript -r--r--r-- 1 otto 137111 Apr 6 10:18 k-ls-p.ps.Z -r--r--r-- 1 otto 52987 Apr 6 09:43 linti.ps.Z of the papers Kalmar, linear space, and P The linear time hierarchy via tiers and monoidal categories The 1st paper has recently been lightly revised. But some of the ideas there have evolved past what is written there. The 2nd paper is more recent and hasn't been here before. ghostview, version 1.5, can preview these, when uncompressed, and save marked pages. For comments or help please contact Jim Otto otto@math.mcgill.ca Date: Thu, 7 Apr 1994 15:54:50 +0500 (GMT+4:00) Subject: local homeomorphisms Date: Thu, 7 Apr 1994 17:07:35 +0200 From: kock@mi.aau.dk Re: local homeomorphisms, and etendues Comment on Feldman's description of binary products in the category of spaces and local homeomorphisms. The product of an object X with itself is always the (object of arrows of) a groupoid, usually a rather uninteresting one. But in the category of spaces and local homeomorphisms, it is a very interesting groupoid, usually denoted \Gamma X (the pseudogroup of (germs of) local automorphisms of X, considered by Haefliger (and others?) back in the 1950's. It is also a groupoid in the category of spaces and all continuous maps, since pull-backs are preserved by the forgetful functor. For similar reasons, X times Y is a principal bundle over the groupoid \Gamma X (acting from the left), and \Gamma Y (acting from the right). Similar considerations apply in the category of locales. The corresponding localic groupoids were in essence considered by Ehresmann in "Gattungen von lokalen Strukturen", under the name of _local_ groupoids. I presented an expose about this, and its relatinship to etendue theory at the PSSL in Sussex in March, and the manuscript I circulated, may be picked up by ftp from theory.doc.ic.ac.uk, directory papers/Kock. It is called sussex.dvi. Anders Kock Date: Thu, 7 Apr 1994 15:53:19 +0500 (GMT+4:00) Subject: colloquium Date: Thu, 7 Apr 94 14:32:45 +0200 From: Giuseppe.Longo@ens.fr LOGICAL RATIONALITY AND GEOMETRIC INTUITION "Rationalite' logique et intuition geometrique" Paris, 9 and 10 June 1994 Ecole Normale Superieure, 45, rue d'Ulm, Salle Dussane 75005 Paris Jointly organised by the Departement Mathematiques et Informatique de l'ENS, CREA (Ecole polytechnique - CNRS) and the Institut d'histoire et de philosophie des sciences et des techniques (Paris I - CNRS) Organizers: Daniel Andler (CREA & Paris X - Nanterre), Giuseppe Longo (CNRS, ENS) et Hourya Sinaceur (CNRS, IHPST) Thursday June 9, 1994 9h30 Ouverture du colloque: E. Guyon (Directeur, ENS) 10h Rene Thom (IHES) : L'efficacite' pragmatique des mathematiques est-elle due a` la logique ou a` l'intutition geometrique? 10h50 Repondant : Giuseppe Longo (ENS) 11h15 Discussion 12h Aperitif 14h Alain Berthoz (College de France) : La geometrie euclidienne a-t-elle des fondements dans l'organisation des systemes sensoriels et moteurs ? 14h50 Repondant : Frederic Nef (Universite de Rennes) 15h15 Discussion 15h50 Pause 16h10 Jean Petitot (EHESS) : Logique geometrique et statut modal de l'espace 17h Repondant : Bernard Teissier (ENS) 17h25 Discussion Friday June 10 9h Dana Scott (Carnegie Mellon University) : Infinitesimals 9h50 Repondant : David Miller (Warwick College) 10h15 Discussion 10h50 Pause 11h10 Pierre Cartier (ENS)Algebrisation de la geometrie (et vice versa) 12h Repondant : Marie-FranIoise Roy (universite de Rennes) 12h25 Discussion 14h30 Lamberto Maffei (Scuola Normale Superiore, Pise) : What Galileo's brain told Galileo's eye 15h20 Repondant : Jacques Ninio (ENS) 15h45 Discussion 16h20 Pause 16h30 Daniel Andler (CREA) : Synthese des journees Information: auffray@dmi.ens.fr Date: Thu, 7 Apr 1994 23:08:35 +0500 (GMT+4:00) Subject: Workshop on Log., Lang., Inf. & Comp. Date: Thu, 07 Apr 1994 16:31:48 -0500 (EST) From: Ruy de Queiroz (PLEASE NOTE NEW DEADLINE, AND NEW INVITED SPEAKER) Workshop on Logic, Language, Information and Computation WoLLIC '94 July 28--30, 1994 Recife, Brazil A Workshop on Logic, Language, Information and Computation, will be held in Recife, on the northeastern coast of Brazil, from 28th to 30th July 1994. Contributions are invited in the form of one page (300 words) abstract in all areas related to logic, language, information and computation, including: pure logical systems, proof theory, model theory, type theory, constructive mathematics, lambda and combinatorial calculi, program logic and program semantics, nonclassical logics, nonmonotonic logic, logic and language, discourse representation, logic and AI, automated deduction, foundations of logic programming, logic and computation, and logic engineering. There will be a number of guest speakers, including some who are already part of the advanced seminars of the parallel event (see below): J. Barwise (Indiana), J. Cunha (Porto), J. Fiadeiro (Lisbon), D. Gabbay (London), J. Lambek (McGill), T. Maibaum (London). Four others have confirmed their participation: N. da Costa (Sao Paulo), H. J. Ohlbach (Saarbruecken), U. Reyle (Stuttgart), K. Segerberg (Uppsala). Submission: One page abstracts (preferably by e-mail to the address *** wollic94@di.ufpe.br ***) must be RECEIVED by **MAY 15, 1994**. Authors will be notified of acceptance by June 5, 1994. WoLLIC '94 is sponsored by the Interest Group in Pure and Applied Logics (IGPL) and The European Foundation for Logic, Language and Information (FoLLI). Abstracts from members of the IGPL will be published in the Bulletin of the IGPL (ISSN 0945-9103) as part of the meeting report. Selected contributed papers will be invited for submission to a special issue of the Bulletin. The Workshop will be part of a bigger event being held in Recife during the last week of July 1994: the (Brazilian) IXth School of Computing, a large biennial event in computer science in the context of Latin America. As some of the invited speakers for the Workshop will be giving advanced seminars (in the form of short courses) on logic and computation in the School, the Workshop will benefit from the fact that the School will attract a fair number of young researchers and students in computer science from all over Latin America. (The School is expected to have an audience of approx. 600 participants.) The location: Recife is the capital of the sun belt coast in the northeast of Brazil, just 8 degrees below Equator, bathed by 250+ days of sun/year (i.e. Caribbean-like climate). City population is around 2.5 million and the life style is quite relaxed. Recife is over 450 years old, has a number of interesting architectural samples of Portuguese colonial times (esp. XVII and XVIII centuries), and is neighbour to picturesque Olinda, whose architectural heritage is protected by UNESCO. Programme Chair: Prof P. A. S. Veloso, Attn: WoLLIC '94, Departmento de Informatica, PUC-Rio, Rua Marques de Sao Vicente, 225, Rio de Janeiro, RJ 22453-900, Brazil, veloso@inf.puc-rio.br, tel: +55 21 529 9524, fax: +55 21 511 5645. (Please send abstracts to wollic94@di.ufpe.br) Programme Committee: W. A. Carnielli (UNICAMP, Campinas), M. Costa (EMBRAPA, Brasilia), V. de Paiva (Cambridge, UK), R. de Queiroz (UFPE, Recife), A. Haeberer (PUC, Rio), T. Pequeno (UFC, Fortaleza), L. C. Pereira (PUC, Rio), A. M. Sette (UNICAMP, Campinas), P. Veloso (Chair, PUC, Rio). For further information, contact the Chair of Organising Committee: R. de Queiroz, Departamento de Informatica, Universidade Federal de Pernambuco em Recife, Caixa Postal 7851, Recife, PE 50732-970, Brasil, tel:+55 81 271 8430, fax +55 81 271 4925, ruy@di.ufpe.br. Co-Chair: Tarcisio Pequeno, LIA, Universidade Federal do Ceara, tarcisio@lia1.ufc.br, fax +55 85 223 1333. Date: Mon, 11 Apr 1994 16:26:44 +0500 (GMT+4:00) Subject: postdoctorate stay Date: Fri, 8 Apr 1994 11:26:24 +0200 (MET DST) From: Jiri Rosicky Department of Mathematics, Masaryk University, Brno, Czech Republic offers a postdoctorate position for the period September (October) - December 1994. Send applications together with C.V. by May 10 to A.Sekaninova Department of Mathematics Masaryk University Janackovo nam. @a 66295 Brno Czech Republic fax: 425-41210337 e-mail: asekanin@math.muni.cz Date: Mon, 11 Apr 1994 16:27:58 +0500 (GMT+4:00) Subject: FMCS 94 Accomodation Date: Fri, 8 Apr 94 13:48:15 -0700 From: John MacDonald University of British Columbia REQUEST FOR ACCOMMODATION AT WALTER GAGE COMPLEX Foundational Methods in Computer Science, June 2-5, 1994 --------------------------------------------------------------------- last name: . . . . . . . . . . . . .first name: . . . . . . . . . . . address: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . city:. . . . . . . . . . state/province: . . . . . zip/postcode: . . country: . . . . . . . . . . . . . . telephone number: . . . . . . . Arrival Date, Month: . . . . . . . . . Day: . . . . . . . . . . . . CHECK IN after 2:00 pm Departure Date, Month: . . . . . . . . . Day: . . . . . . . . . . . . CHECK OUT before 11 am Shared Washroom [ ]Single room with shared washroom $32.00 room/night Private Washroom [ ]Single room (single bed) . . . .$52.00 room/night [ ] Suite (double bed) . . . . . . $70.00 room/night [ ] Deluxe suite (twin beds; living room with TV, telephone, sofa-bed; kitchenette) . . . . . . . . . $91.00 room/night If requesting a Suite, please advise number of people: [ ] PAYMENT INFORMATION. Full payment in Canadian funds is due at check-in by cash, travellers' cheques, VISA or MasterCard (no personal cheques). There is no guarantee required for shared washroom accommodation. However, private washroom accommodation has to be guaranteed with VISA or MasterCard or with deposit by bankdraft in Canadian funds for the equivalent of one night. A one-night cancellation charge applies if cancellation in writing is not received 48 hours prior to check-in-date. [ ] VISA [ ] MASTERCARD Expiry Date: (Month: Year: ) CARD NO: ____________________________________________________ CARDHOLDER'S SIGNATURE: _____________________________________ DATE SIGNED: _______________________________________________ Group Code G40602A ====================================================================== Please mail or fax the form above before May 2, 1994, to: Reservations Office, UBC Conference Centre, 5901 Student Union Blvd., Vancouver, BC, V6T 2C9, Canada. Tel: (604) 822-1010, Fax: (604) 822-1001 Single rooms with shared washroom will be substituted when requests for private washroom cannot be accommodated. All rates are quoted in Canadian funds and are subject to applicable taxes. ---------------------------------------------------------------------- Remarks from organizers: 1. Please send the above reservation form either by fax to the number given or by paper mail to the Reservations Office at the above address. 2. Please do not send reservation forms to the organizers. 3. Please note that accomodation should be booked before May 2, 1994. This accomodation is within easy walking distance of the talks and the student cafeteria. 4. Only a limited amount of accomodation has been booked. Thus if attendance is significantly higher than last year then available space may run out. Early reservations are recommended. 5. If you choose to stay in a Vancouver hotel then you will need to come in to the talks each day by bus or car. You should make such bookings yourself directly or through a travel agent since we will be unable to handle hotel bookings, due to the volume of other correspondence. John MacDonald & Art Stone, organizers Date: Thu, 14 Apr 1994 16:58:41 +0500 (GMT+4:00) Subject: postdoc Date: Wed, 13 Apr 94 18:02:13 EDT From: Michael Barr It turns out that despite my doubts, we did get the grant from the province that we had applied for and it seems we can support one postdoc. I forgot to check what the salary is, but it is probably in the vicinity of $30K and can be topped up a bit with some teaching, which the chairman says is still available. We have two applications already and I will consider others. Please send an application and two letters of reference to me if you are interested. I will be away from April 21 to May 1, so let me say that the letters should be in my hand by May 1. Fax and email accepted. The fax number is (514) 398-3800 and my name should be on it. Michael Barr Date: Thu, 14 Apr 1994 16:59:20 +0500 (GMT+4:00) Subject: change it Date: Thu, 14 Apr 94 17:03:10 BST From: Dusko Pavlovic In the last couple of weeks, I kept catching myself in --- uhm --- philosophical discussions re. category theory. They were a bit hectic, and didn't get very far... You know, for most mathematicians, philosophy is a no-go area; one takes care not to get too involved. But category theorists seem to be driven to it, somehow. (Sometimes, at least.) Anyway, hoping for comments from more experienced people, and apologizing to those who don't want to be bothered, I would like to put forward a couple of themes that keep coming back to me. The starting point for one of those discussions was my paper Maps II. Why is that simple characterisation so complicated in details? Doesn't that mean that the setting is wrong? In a more extreme and less serious form, I've heard a similar objection to somebody else's work: "It is too complicated to be of interest". Yes, category theory is the discipline of conceptual mathematics: it helps us extract the relevant structure and discard the contingent. "Mental hygiene" is a nice metaphor. Categories provide means for analyzing complex situations into conceptual parts. In a sense, they embody the first commandment of the Cartesian Method: DIVIDE. They are tools of understanding --- so they should at least be transparent and easy to understand themselves, shouldn't they? But they are not. The complexity issue arises on a rather general plan. For instance, in a recent issue of the Advances in Mathematics, in the review of our 1991 Montreal proceedings, Gian-Carlo Rota says that it's good that categories are still alive and well, but suggests that all those papers should be written in two versions --- the second one for people who might need some encouragement before "swallowing this morass of definitions". I don't suppose you need to hear the more extreme and less serious objections this time. Everybody knows that most mathematicians think of category theory just as their yoga instructors, their grandmothers and so on think of mathematics: it's complicated and useless. Of course, yoga instructors are less likely to be right about maths than mathematicians about categories; and those objections to my work are probably right, at least to some extent. So I am not trying to transform a criticism of me into a criticism of the State. They are quite different --- but somehow analogous, and I am trying to understand what lies behind. Is the complexity phenomenon just subjective (and more so in the narrower part of the telescope) or not? I mean, does the morass arise just from our wrong settings and overly complicated proofs --- feeding people's prejudice --- or is there more to it? Well, I think there is often less! I want to argue for the possibility that morass is at some places a natural state of ground, AND not always bad or dangerous. But let me try to put this in less extreme and more serious terms. (OK, I won't use this figure any more.) Categories are about understanding. Understanding is a process in time; but when it is achieved, it can often be summarized in a moment, captured by a picture. For instance, the periodic system of elements. In category theory, instead of wandering among equations, we draw a diagram to see what happens. Even for a hardest theorem, one often finds a crucial point or two, which can be retained in our mind's eye. Then we say we understand. Sometimes, however, understanding is essentially dynamical, and cannot be fixed. You may understand topology, but you can hardly survey it in a glimpse, compress it into a single idea. Or take natural language: we understand sentences as they go, without memorizing them or trying to capture the structure. In the morass of language, we move like centipedes, not worrying which leg comes after the 32nd. In mathematics and exact sciences, one tends to be sceptical towards this dialectical kind of understanding. The imperative of logical certainty seems to preclude it. "Clare et distincte", commanded Cartesius, and his voice still resounds very clearly. Mathematics takes good care not to become a natural language! Things should be cristal clear. Even a philosopher like me gets this. But when I look at our concrete mathematics --- there are all those strange phenomena, more and more of them, leading people to question the feasibility of the current criteria of logical certainty. Every month, an important new result is announced, with a proof that either just computers can check, or less than 7 people around the globe can hope to understand. Many of these proofs come with gaps --- but then there is this new branch of computational proof theory which measures how economic it is to allow such gaps. To a pure pure mathematician, this is ultimate horror, although it is perhaps better than the current practice of judging the validity of proofs by the concensus of experts. (However, some rather serious people argue that this practice cannot and should not be abolished: Deligne, Thomas Kuhn.) Experts usually agree whether a gap is easy to be filled or not, but for that long sought result about packing spheres like cannonballs, achieved three years ago by Hsiang (I think), the experts have not been able decide if there is a gap or not. Two equally large groups are still arguing that there is and that there ain't. So what can category theory hope for in this heavy-weight world of gaps and cannonballs? Not only in the granting sense, but also --- forgive me --- philosophically? Of course, I don't know the answer. What I wanted to say is that category theory might be some kind of a natural language, whether we like it or not. Hence the morass. But, like sentences in natural language, complicated categorical derivations are usually "simpler than they look", say I. Children make and understand long sentences, without being able to capture their structure. Laws of objective dialectics take care that they don't get lost in the morass. (Otherwise, they could never be careful enough anyway.) A very distinct experience that I had in categorical proof theory: derivations get lengthy, sometimes scary; you get surprised every once in a while --- but in the end, things always turn out to be tame and natural. I wish more people would visit the area. Simplicity, hygiene and logical certainty are, of course, good things when you can afford them, but "some books would be shorter if they were not so short", wrote Kant in the foreword of his first Critique. (Young Wittgenstein did not listen, and wrote that very hygienic book of his, which ended up in silence.) Ata ny rate, we should pay more attention to the dialectical contents of our science, as Lawvere and MacLane have been saying for a long time, more or less explicitly. This becomes even more important now, when it has become clear that the dream of powerful, problem-solving category theory won't come true. Complexities are not all due to a lack of category theory, and cannot be conceptualized away. We should not try to simplify the world, but... (But perhpaps I shouldn't philosophize it too much either.) Cordially, Dusko Pavlovic Date: Fri, 15 Apr 1994 16:28:23 +0500 (GMT+4:00) Subject: Re: change it Date: Fri, 15 Apr 94 9:54:10 CDT From: David Yetter A few brief thoughts on Dusko's discussion: First, almost all definitions in mathematics when done from the ground up are hopelessly complex. Ask your skeptical friends to define a continuous real-valued function on a topological space from first principles (for them, I suppose, from axiomatic set-theory alone). The only reason real numbers (pairs of subsets of the set of equivalence classes of formal ratios of formal differences of things satisfying the Peano axioms, modulo... and satisfying.... ) don't give the same impression is that we are used to them and have consequently forgotten the formal definition and the proceed to use only the properties. One way of making progress in mathematical understanding, indeed the way most congenial to categorists, is to get the definitions right so that one can forget the morass of quantifiers in the definition, and use only the essential properties of the objects under consideration. (Deep results, though, usually come from doing this, then briefly returning to the less abstract level to pull out an unexpected relation between the more abstract and the more concrete: e.g. the Atiyah-Singer Index Theorem, or Shum's freeness result for framed tangles.) It has been a persistent problem for category theory that we are interested in foundational questions (which most mathematicians abhor), and have not made it generally understood that we are really doing a kind of algebra (albeit a kind of algebra so potent that it can be applied to foundations). You might therefore turn aside much criticism by pointing out that category theory is no longer abstract in the sense of having no really interesting concrete examples: the work of Joyal/Street, Freyd/Yetter, Shum, Turaev, Reshtikhin, Majid, Lyubashenko, (the physicists) Moore/Seiberg, Kapranov/Voevodsky, and Fisher (to name but a few) are full of remarkable categories (with additional structure requiring yet more complex definitions!) with intimate connections to low-dimensional topology and Hopf algebra theory. Similarly, coming from the more foundational uses of category theory, the realizability topos is surely one of the most beautiful objects anywhere. (Indeed, topoi in general are quite beautiful.) --David Yetter Date: Fri, 15 Apr 1994 16:26:46 +0500 (GMT+4:00) Subject: Re: change it Date: Fri, 15 Apr 1994 11:08:38 -0400 (AST) From: RDAWSON@HUSKY1.STMARYS.CA Dusko Pavlovic raises some interesting points - I just want to comment quickly on a couple of them. Firstly, it may be that (like those annoying "semiconvergent" series in numerical analysis), attempts to clarify something pass through a point of maximum simplicity after which they get worse again. Given all the indications that we can't have the kind of foundations that were once sought after (Goedel and All That), perhaps we are just looking for that point? The other comment addresses the idea that children use complex grammatical structures without completely understanding them. Sure they do - but they don't always use them *correctly*. Neither, of course, do adults. The trouble with mathematics is that unlike most of what we use natural language for, its groundrules don't (despite certain recent articles) permit statements on the 'well, it's mostly right and everybody knows what I mean' level. Most natural language usage jumps out of the system all the time... which gets into the AI debate. In mathematics, the medium is much closer to being the message. We try not to get into situations similar to the old chestnut "Time flies like an arrow, while fruit flies like a banana." , supposed by some to show that computers can't parse English. (I'm not sure that it does, any more than if I say 'Professor Smith is visiting next week' and you don't know whether to ask 'Is he?' or 'Is she?' , that shows that *you* don't know how to parse English...) But natural languages do, because in "natural" situations there is something outside the linguistic universe that can be referred to usefully. -Robert Dawson Date: Fri, 15 Apr 1994 16:30:59 +0500 (GMT+4:00) Subject: position available Date: Fri, 15 Apr 94 17:41:01 METDST From: Peter Knijnenburg Leiden University - The Netherlands The Department of Computer Science invites applications for a position of Full Professor of Computer Science The department offers a master's program in computer science for both full-time and part-time students, as well as a Ph.D degree in computer science. It has 18 regular faculty members and a technical support staff. There are research groups in theoretical computer science, information systems and software engineering, high performance computing and computer graphics, CAD and geometric modelling. Hardware facilities include networks of SUN, HP, Silicon Graphics workstations, PC networks, a MasPar MP1 multiprocessor system, and a Parsytec MultiCluster system. Candidates must have a relevant Ph.D, a strong commitment to teaching, and a strong record of research accomplishment. Especially desired are candidates with a proven research record in areas such as programming languages, semantics, specification, verification, program transformation, logic, design and analysis of algorithms, and foundations of artificial intelligence. For more information please contact the chairman of the search committee, Professor G. Rozenberg, Department of Computer Science, Leiden University, Niels Bohrweg 1, NL-2333 CA Leiden, The Netherlands, (tel.: +31-71-277063, e-mail: rozenber@wi.Leidenuniv.nl, fax: +31-71-276985). Applications accompanied by a detailed c.v., list of publications, and the names of at least three references should reach Dr. J. Coremans, Managing Director, Huygens Laboratory, Niels Bohrweg 2, NL-2333 CA Leiden, The Netherlands, not later than May 15, 1994. Date: Fri, 15 Apr 1994 16:35:16 +0500 (GMT+4:00) Subject: LICS'94 registration and ASL members Date: Thu, 14 Apr 94 16:48 EDT From: Amy Felty LOGIC IN COMPUTER SCIENCE ******************************** Ninth Annual IEEE Symposium July 3-7, 1994, Paris, France Please note the following correction to the LICS'94 registration information: the member rate also applies to members of the Association for Symbolic Logic. [Complete program and registration information is available on the world-wide web at http://www.research.att.com/lics/ Postscript, dvi, latex and plain text versions of the conference brochure are available via anonymous ftp from research.att.com in directory /dist/lics.] Date: Mon, 18 Apr 1994 16:57:40 +0500 (GMT+4:00) Subject: Re: change it Date: Mon, 18 Apr 94 12:52:07 EDT From: Peter Freyd Dusko Pavlovic offers, in passing, several descriptions of category theory: Yes, category theory is the discipline of conceptual mathematics: it helps us extract the relevant structure and discard the contingent. Categories provide means for analyzing complex situations into conceptual parts. Categories are about understanding. We know how to respond to students who tell us that they understand the material but can't do the problems. So how does one respond to this? I would suggest that any branch of mathematics is justified finally only because it allows us to prove things previously unprovable. If we were restricted to doing things we understand I don't think we would have gotten very far. Indeed, the most conspicuous function of mathematics I know is that it allows us to do things we don't yet understand. In my experience the feeling of understanding doesn't come until after the problems are solved. And sometimes long after. I think there are strong cases to be made for the presence of categories in mathemamatics (beginning at least with the Adams operations). And I think there are good cases to made even for the _theory_ of categories in mathematics. But -- something none of us expected -- the best cases to be made for the theory of categories are not in mathematics but in applied areas. It is there that we are finding the refutation of Dusko's sad assertion "now when it has become clear that the dream of powerful, problem-solving category theory won't come true." Date: Thu, 21 Apr 1994 14:48:54 +0500 (GMT+4:00) Subject: European Colloquium of Category Theory Date: Wed, 20 Apr 1994 15:43:27 UTC+0200 From: damphous@univ-tours.fr EUROPEAN COLLOQUIUM on CATEGORY THEORY in Tours (France) July 25-29 1994 ---- ECCT ---- FIRST ANNOUNCEMENT (APRIL 20 1994) A European Colloquium on Category Theory (ECCT) will be held in TOURS (France) from July 25th to July 29th, the week before the International Congress of Mathematics in Z\"urich, under the honorary presidency of Professor Saunders MacLane, with Samuel Eilenberg as guest star. Mathematicians foreseeing to be present in Europe at that time who whish to attend or participate are most welcome to pre-registe in order to receive pertaining information. Paper may still be submitted for a limited period not exceeding June 1st. The scientific committee is composed of : J. Adamek (Prague); J. B\'enabou (Paris); F. Borceux (Louvain); A. Carboni (Genova); P. Damphousse (Tours); Y. Diers (Valenciennes); R. Guitart (Paris); J. Gray (Urbana); H. Herrlich (Bremen); P. Johnstone (Cambridge); M. Kelly (Sidney); I. Moerdijk (Utrecht); G. Reyes (Montreal). To pre-register, you must proceed as follows: send an e-mail to ECCT-request@univ-tours.fr, with the following line in the body of the message (with no subject in this e-mail): SUBSCRIBE For any further information, contact Pierre Damphousse at damphous@univ-tours.fr (Note : due to construction works, the computer center at the above address will close from april 25 to april 28.) Date: Fri, 22 Apr 1994 15:12:36 +0500 (GMT+4:00) Subject: Books on categories in computer science Date: Fri, 22 Apr 94 09:09:54 PDT From: "Michael J. Healy (206) 865-3123" I am asking for recommendations for a book. Some industrial mathematicians and computer scientists are forming a category theory study group, and want to use a book that gives an introduction to categories in computer science. We would like one that is self-contained in that it contains definitions and, if appropriate, examples for all categorical terms including those specialized to computer science. We're looking primarily at applications in specification-based software synthesis, and design synthesis in general. If you care to respond, my email address is mjhealy@atc.boeing.com. Thank you, Mike Healy Date: Mon, 25 Apr 1994 14:00:53 +0500 (GMT+4:00) Subject: What is a "principal fibration" ? Cc: cdl2 -- France Dacar , Robert Dawson , "Oege de.Moor" , "Valeria de.Paiva" , "Ruy de.Queiroz" , Gabriela DeVivo , "Fer-Jan De.Vries" , Kyung-Goo Doh , James Dolan , Xiaomin Dong , Winfried Drecmann , Dominic Duggan , Gerald Dunn , Hans Dybkjaer , Abbas Edalat , David Espinosa , Michel Eytan , Joe Fasel , David Feldman , Zbigniew Fiedorowicz , Juarez Muylaert Filho , Stacy Finkelstein , Kathleen Fisher , Maria Frade , Peter Freyd , Tom Fukushima , Jonathan Funk , Fabio Gadducci , Vijay Gehlot , Wolfgang Gehrke , Silvio Ghilardi , Paul Glenn , Joseph Goguen , Marek Golasinski , Al Goodloe , Bob Gordon , Francoise Grandjean , John Gray , Luzius Grunenfelder , Stefano Guerrini , Alessio Guglielmi , James Harland , Robert Harper , Magne Haveraaen , "Michael J. Healy" , Michel Hebert , Luis Javier Hernandez , Walt Hill , SATO Hiroyuki , Bernard Hodgson Date: Mon, 25 Apr 94 18:40:59 +0200 From: Thomas Streicher I have heard that in the Grothendieck school there has developed a notion of "principal fibration" which should generalize the notion of principal bundle ! Please, could anyone give me a reference ! Thomas Streicher Date: Mon, 25 Apr 1994 14:00:16 +0500 (GMT+4:00) Subject: Tortile tensor cats Date: Mon, 25 Apr 1994 07:52:29 -0400 From: James Stasheff Mei Chee Shum's `Tortile tensor cats' has appeared in the latest JPAA 93 (1994) 57-110. jim Date: Tue, 26 Apr 1994 15:29:47 +0500 (GMT+4:00) Subject: Diocletian Date: Tue, 26 Apr 94 09:19:01 EDT From: Peter Freyd It seems that somewhere between 284 and 305 Diocletian proclaimed: Artem geometriae discere atque exercere publice interest, ars autem mathematica damnabilis interdicta est omnino. Does that say what I think it does? Can someone supply an authoritative translation? Date: Tue, 26 Apr 1994 15:29:30 +0500 (GMT+4:00) Subject: RE: What is a "principal fibration" ? Date: Tue, 26 Apr 94 9:17 GMT From: MAS013@bangor.ac.uk I do not remember the notion in Grothendieck's work, but the term princial fibration was extensively used with simplicial sets. the theory is very pretty and can be found in the survey by Curtis in Adv. in Maths. 6 (1971) 107 - 209. Given the close connections between Simplicial sets and category theory this may provide a solution to your problem. Tim Porter mas013@uk.ac.bangor Date: Tue, 26 Apr 1994 22:37:39 +0500 (GMT+4:00) Subject: Re: What is a "principal fibration" ? Date: Tue, 26 Apr 1994 18:57:44 -0400 From: James Stasheff hadn't heard of that one but there is a notion of principal fibration in alg top/homotopy theory the based path space with loop space as fibre is the stereotypical example jim Date: Tue, 26 Apr 1994 22:41:35 +0500 (GMT+4:00) Subject: Re: Diocletian (times 3) Date: Tue, 26 Apr 94 13:44:46 PDT From: "Scott L. Burson" Date: Tue, 26 Apr 94 09:19:01 EDT From: Peter Freyd It seems that somewhere between 284 and 305 Diocletian proclaimed: Artem geometriae discere atque exercere publice interest, ars autem mathematica damnabilis interdicta est omnino. Does that say what I think it does? Can someone supply an authoritative translation? Yep, it means just what it looks like: To learn and practice the art of geometry is publicly of interest, but the damnable mathematical art is proscribed altogether. -- Scott ++++++++++++++++++++++++++++++ Date: Tue, 26 Apr 94 20:14:21 EDT From: Moez Alimohamed Peter Freyd's writes: It seems that somewhere between 284 and 305 Diocletian proclaimed: Artem geometriae discere atque exercere publice interest, ars autem mathematica damnabilis interdicta est omnino. Does that say what I think it does? Can someone supply an authoritative translation? ------------------------------- In translation, this reads: Learning the art of geometry and furthermore, using it on behalf of the state is of interest - nevertheless, mathematics is altogether worthy of condemnation and is forbidden. Very strongly worded. Date: Tue, 26 Apr 94 20:17:54 EDT From: Moez Alimohamed The translation of Diocletian contained in the previous posting is due to the mathematician and Latin scholar Raymond Thomas (rlt@cunyvms1.gc.cuny.edu) ++++++++++++++++++++++++++++++++++++++++++++++++++++ Date: Tue, 26 Apr 94 21:00:23 EDT From: Walter My translation would be: "To learn and (especially) to practice the art of geometry is generally of importance (or: is in the public interest) , the condemnable art of mathematics, however, is altogether forbidden." Walter Tholen. Date: Wed, 27 Apr 1994 13:15:19 +0500 (GMT+4:00) Subject: More on geometriae/mathematica Date: Wed, 27 Apr 94 14:54:11 +1000 From: Max Kelly The Latin of Peter Freyd's quotation from Diocletian may be translated: To teach and exercise the art of geometry is in the public interest; the damnable art of mathematics, however, is forbidden to every man. The point, surely, is that in those days "mathematics" meant "astrology". See Augustine, in The City of God, if I recall correctly. In the twelfth century "Play of Daniel", as performed at Beauvais, when the writing on the wall appears, the king says "Vocate mathematicos" - "call the soothsayers (or astrologers). Regards, Max Kelly. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Date: Wed, 27 Apr 94 01:49:18 EDT From: Peter Freyd The mysterious proclamation of Diocletian, Artem geometriae discere atque exercere publice interest, ars autem mathematica damnabilis interdicta est omnino. (To learn and -- especially -- to practice the art of geometry is in the public interest but the damnable mathematical art is proscribed altogether.) was found as a citation for the once common use of the word "mathematicus" to mean "wizard". Another citation is from England (from Shirley's 1642 comedy "The Sisters"): Giovanni: Master Steward, yonder are the rarest fellows! In such fantastical habits too; they call themselves mathematicians. Steward: What do they come for? Giovanni: To offer their service to my Lady and tell fortunes. ... Antonio: Her house is open for these mountebanks, Cheaters, and tumblers, that can foist and flatter My lady Gewgaw... What are you, sir? Strozzo: One of the mathematicians, noble Signior. Antonio: Mathematicians! mongrel, How durst thou take that learned name upon thee? You are one of those knaves that stroll the country, And live by picking worms out of fools' fingers. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Date: Wed, 27 Apr 1994 10:56:41 -0400 (EDT) From: MTHISBEL@ubvms.cc.buffalo.edu The three translations I have seen here are very nice except for the meaning. *Geometry* means pretty much #mathematics#. *Mathematics* is #divination#. John Date: Thu, 28 Apr 1994 16:33:27 +0500 (GMT+4:00) Subject: The last of Diocletian Date: Thu, 28 Apr 94 08:53:01 +0100 From: Gavin Wraith A propos the Diocletian quote, I support Max Kelly and John Isbell : I do not like to jump in with both feet without seeing the locus and its context, but I would say that the sense is "Surveying is generally acknowledged to be a social benefit but astrology is everywhere taken to be pernicious" "Geometria" at this time would have military overtones - design of fortifications, disposal of forces over terrain etc. "Mathematicus" almost certainly means "astrologer" or "soothsayer". Astrology was not respectable, being seen as a vulgar oriental import. Two centuries earlier, Juvenal in his sixth satire (line 562) says "Nemo mathematicus genium indemnatus habebit" (No astrologer gets a reputation until he is convicted) a line which the Diocletian quote could well be referring back to. Sorry if this is a disappointment - but a nice quote anyhow! -- Gavin Wraith ++++++++++++++++++++++++++++++++++++++ Date: Thu, 28 Apr 1994 11:30:58 +0200 From: France.Dacar@ijs.si > Date: Tue, 26 Apr 94 13:44:46 PDT > From: "Scott L. Burson" > > > Date: Tue, 26 Apr 94 09:19:01 EDT > From: Peter Freyd > > It seems that somewhere between 284 and 305 Diocletian proclaimed: > > Artem geometriae discere atque exercere publice interest, > ars autem mathematica damnabilis interdicta est omnino. > > Does that say what I think it does? Can someone supply an > authoritative translation? > > Yep, it means just what it looks like: > > To learn and practice the art of geometry is publicly of interest, but the > damnable mathematical art is proscribed altogether. > > -- Scott Appearances might be misleading. What precisely were the meanings of "geometria" and "mathematica" in Diocletian times? I suspect that "geometria" encompassed what we would call the whole of mathematics as known then, while "mathematica" was a branch of sorcery (benign as well as malign, ie. both white and black) that involved much high-fallutin' twiddling of symbols, mysterious diagrams and geometric figures, and such -- thus a kind of formalized abstract magick. (Some recent literature on uses of category theory in computer science in general and in AI in particular would be basic manuals, as it were, for those mathematically inclined sorcerers. They could use them quite effectively even if they would not understand what it's all about, since they could always pretend they do, and they were masters of illusionism.) Can somebody tell whether this is a good enough guess? ------------------------------------------------------------------------ France Dacar Email: france.dacar@ijs.si Computer Science Department Phone: +386 61 1-259-199 / 768 Jozef Stefan Institute Fax: +386 61 1-258-058 Jamova 39, 61000 Ljubljana, Slovenia Date: Thu, 28 Apr 1994 16:30:10 +0500 (GMT+4:00) Subject: Cubical monads Date: Thu, 28 Apr 1994 15:15:13 +0200 From: Marco Grandis The following preprint is available "Cubical homotopical algebra and cochain algebras" Marco Grandis. Abstract. Basic homotopical algebra is developed in a setting consisting of a cubical monad (*), i.e. a cylinder endofunctor I, equipped with connections g-, g+: I^2 -> I, and - possibly - with symmetries extending the reversion r: I -> I and the interchange s: I^2 -> I^2 of the standard topological case. Our study is mostly concerned with the Puppe sequence of a map f and its comparison with the sequence of iterated homotopy cokernels of f. As an application, the homotopy structure of cochain algebras is studied in the present frame, through the cubical co-monad of the path functor P and the left adjoint cylinder functor I. This paper is a sequel of (*) "Cubical monads and their symmetries", whose abstract appeared in "CATEGORIES", Mon, 4 Oct 1993. Regards, Marco Grandis Dipartimento di Matematica, Universita di Genova, Via L.B. Alberti 4, I - 16132 Genova, Italia e-mail: grandis@dima.unige.it