March 1993 - Categories - categories.org.au

a paper
by pavlovic＠triples.Math.McGill.CA 01 Apr '93

01 Apr '93

A paper on logic and factorisations MAPS I: RELATIVE TO A FACTORISATIONS SYSTEM by Dusko Pavlovic is available by anonymous ftp from triples.math.mcgill.ca. The file is called mapsI-A4.dvi.Z (or mapsI-US.dvi.Z). It is in the directory pub/pavlovic. Please let me know if you have problems fetching or printing this file. Regards, Dusko Pavlovic Abstract Originally, the categorical calculus of relations was developed using the canonical factorisation in regular categories. More recently, relations restricted to a proper factorisation system have been studied by several authors. In the present paper, we consider the general situation, in which relations are induced by an arbitrary stable factorisation. This extension of the calculus of relations is necessary for a categorical development of strongly constructive (and computational) logic, where non-monic relations come about naturally. In this setting, we analyze the correspondence of the maps, i.e. the total, single-valued relations, and the functions, as given by the arrows in the underlying category. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

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Fall Meeting at McGill
by fox＠triples.Math.McGill.CA 19 Mar '93

19 Mar '93

C --- R | / | CENTRE de RECHERCHE en THEORIE des CATEGORIES | / | CATEGORY THEORY RESEARCH CENTER T --- C CATEGORY THEORY OCTOBERFEST: FIRST ANNOUNCEMENT McGill University, Montreal Saturday-Sunday, October 9-10, 1993 Dear Colleague, Once again this October the Category Theory Research Center will sponsor a weekend meeting at McGill University. This annual event brings together mathematicians interested in the categorical aspects of logic, computer science, combinatorics, universal algebra, homological algebra, topology, analysis, and theoretical physics. If you wish to speak, please contact Michael Barr. We particularly wish to encourage advanced students and new PhDs to use this forum to disseminate their work. A list of hotels and tourist rooms will be distributed in the Fall, along with a preliminary list of speakers. The final schedule of talks be drawn up the morning of Oct 9. If you have any further questions, please contact Tom Fox. CRTC Dept of Mathematics and Statistics McGill University 805 Sherbrooke West Montreal, Quebec CANADA H3A 2K6 Michael Barr barr(a)triples.math.mcgill.ca Tom Fox fox(a)triples.math.mcgill.ca

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New address
by Francois Lamarche 16 Mar '93

16 Mar '93

Category theorists of the world, I am informing you that my new address is Francois Lamarche Department of computing Imperial College (of Science and Technology) 180 Queen's Gate London SW7 2BZ UK e-mail gfl(a)doc.ic.ac.uk ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

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TEMPUS SUMMER SCHOOL
by TEMPUS of Dept. of Algebra and Geometry 12 Mar '93

12 Mar '93

Tempus Summer School for Algebraic and Categorical Methods in Computer Science First Announcement Brno, June 28 - July 3, 1993 Sponsored by the European Community TEMPUS office the organizers are pleased to announce an intensive course designed to serve its students as a forum for exchange of ideas between the disciplines of mathematics and computer science. In particular, to carry out the broad mission of the TEMPUS program, the Summer School will provide some of the ablest young scholars in Central Europe with an opportunity to learn from and speak directly with world renowned experts as well as to exchange ideas with the partici- pants from Western Europe. Courses: P. J. Freyd (Philadelphia), Cartesian Logic and Cartesian Categories Y. Lafont (Paris), Linear Logic J. Lambek (Montreal), Categories and Deductive Systems C. P. Stirling (Edinburgh), Modal and Temporal Logics for Processes G. Winskel (Aarhus), Models and Logic for Concurrent Computation Special lecture: D. S. Scott (Linz), The Theory of Domains: Origin, Development, Future Lectures will be held starting Monday morning, June 28, to Saturday noon, July 3; Wednesday afternoon is reserved for social activities. Each course will consist of five lectures,one lecture per day. Fees: Conference fee is 220 DM, (tuition 100 DM, accomodation 120 DM). Price includes accomodation in double bedrooms, breakfast and lunch. Registration: Please send name, address (including e-mail, if available) and gender to the organising office by April 30, 1993.Please indicate if you plan to bring a guest or indicate the name of participant with whom you wish to share accommodation. Scholarships: Under sponsorship of the TEMPUS project, there are 40 scholar- ships available for students of partner universities. These will cover travel, accommodation and tuition. The recipients will be selected by the responsible persons at these universities. Organizing Committee: Jiri Rosicky Anna Sekaninova Jan Slovak Address: TEMPUS SUMMER SCHOOL Department of algebra and geometry Masaryk Univerzity Janackovo nam. 2a 662 95 BRNO Czech Republic e-mail: tempus(a)adelard.dcs.muni.cs fax: 42-5-74 55 10 (from April 42-5-41 21 03 37) phone: 42-5-74 56 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

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CTCS93 Announcement
by David Rydeheard 09 Mar '93

09 Mar '93

Full details to be posted soon, here are the dates and venue for your diary. ----------------------------------------------------------------------------- 1993 *************** Announcement **************** * * * CATEGORY THEORY AND COMPUTER SCIENCE * * ------------------------------------ * * * * Fifth Biennial Meeting * * * ********************************************** CTCS-5 Dates: 7th-10th September 1993. Venue: CWI, Amsterdam, The Netherlands. The fifth of the biennial conferences on category theory and computer science is to be held in Amsterdam in 1993. The purpose of the conference series is the advancement of the foundations of computing using the tools of category theory, algebra, geometry and logic. Whilst the emphasis is upon applications of category theory, it is recognised that the area is highly interdisciplinary and the organising committee welcomes submissions in related areas. Topics central to the conference include: * The semantics of computation * Program logics and specification * Type theory and its semantics * Domain theory * Linear logic and its semantics * Categorical programming Submissions purely on category theory are also acceptable as long as the applicability to computing is evident. Previous meetings have been held in Guildford (Surrey), Edinburgh, Manchester and Paris. The format of this fifth meeting is to differ from previous meetings. Abstracts of talks are to be submitted to the organiser (details below). These will undergo a preliminary selection procedure and authors will be notified of the result. Proceedings of the conference will appear in a special issue of the journal Mathematical Structures in Computer Science. All contributors to the conference will be invited to submit full papers to the special issue. Submissions will undergo the usual refereeing process for MSCS, which accepts only very high standard contributions. Organising and program committee: S. Abramsky, P.-L. Curien, P. Dybjer, G. Longo, G. Mints, J. Mitchell, E. Moggi, D. Pitt, A.Pitts, A. Poigne, D. Rydeheard, F-J. de Vries, E. Wagner. IMPORTANT DATES Submission of abstracts of talks 25th May 1993 Notification of acceptance 1st July 1993 Submission of Abstracts. Authors should send 3 hard copies of an abstract and a cover page (preferably in 11pt LaTeX format) to: Dr. David Pitt, Department of Mathematics University of Surrey, Guildford, Surrey GU2 XH United Kingdom. email: d.pitt(a)mcs.surrey.ac.uk Authors without access to reproduction facilities may submit a single copy of their submission. The cover page of the submission should include the title, authors, a brief synopsis, and the corresponding author's name, address, phone number, fax number, and e-mail address if available. Abstracts should consist of no more than 3 (three) A4 sides (not including references). They must be in English, clearly written, and provide sufficient detail to allow the program committee to assess the merits of the paper. Each submission should make clear the advances made by the authors, the relevance to the subject, the background involved and the relationship to other work in the area. If the authors believe that more details are essential to substantiate the main claims of the paper, they may include a clearly marked appendix to be read at the discretion of the committee. Late abstracts, or those departing significantly from these guidelines, run a high risk of rejection. Local Arrangements: These will be notified later. The local co-ordinator is: Dr. Fer-Jan de Vries Department of Software Technology CWI Kruislaan 413 1098 SJ Amsterdam The Netherlands email: F.J.de.Vries(a)cwi.nl ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

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Announcement PSSL
by bjacobs＠math.ruu.nl 09 Mar '93

09 Mar '93

\documentstyle[12pt,a4]{article} \pagestyle{empty} \begin{document} \begin{center} {\Large\bf Announcement 52$^{\mbox{\small\bf nd}}$ PSSL} \end{center} The 52$^{\mbox{\scriptsize nd}}$ {\em Peripatetic Seminar on Sheaves and Logic} will be held in the weekend of 8 and 9 May 1993 at the University of Utrecht, The Netherlands. As usual, we welcome talks on topics in logic, category theory and related areas. The meeting will be sponsered by NWO and the Faculty of Mathematics and Computer Science. The possibility of a partial refund of local expenses (but not travel) is offered to those who are unable to participate without such support. Both this support and hotel accomodation in Utrecht is limited, so we urge partipants to return the form below as soon as possible, but in any case before April 10. Please publicise this meeting among your colleagues. \medskip We like to point out that Andre Scedrov will be visiting Utrecht in the second week of May and will give a talk on Friday May 7 on computational aspects of linear logic. \medskip Return, preferably by email, to \begin{tabbing} aaaaaa\=aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\=\kill \> Jaap van Oosten, \> Tel. ++31 - 30 - 53.14.78\\ \> Mathematical Institute, RUU, \> Fax ++31 - 30 - 51.83.94\\ \> P.O. Box 80.010, \> Email {\tt oosten(a)math.ruu.nl} \\ \> 3508 TA Utrecht, \> \\ \> The Netherlands. \> \end{tabbing} We look forward to seeing you in Utrecht. The local organizers, \\ Bart Jacobs, \\ Ieke Moerdijk, \\ Jaap van Oosten. \medskip \noindent\hrulefill \medskip \noindent Name \dotfill \noindent Return adress \dotfill \noindent\mbox{}\dotfill \noindent Email \dotfill \medskip \begin{itemize} \item[$\Box$] I wish to give a talk entitled \noindent\mbox{}\dotfill \noindent of 20 / 30 / 45 minutes. \item[$\Box$] I wish hotel accomodation for the nights of 6 / 7 / 8 / 9 May. Please indicate which. \item[$\Box$] I am prepared to share a room (with $\ldots\ldots\ldots\ldots\ldots\ldots$). \item[$\Box$] I do not have access to support covering local expenses. \end{itemize} \end{document} ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

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enriched categories info?
by amnell＠cc.helsinki.fi 08 Mar '93

08 Mar '93

Can anyone recommend good introductions to enriched category theory? I have Kelly's "Basic concepts of enriched category theory", but would like to know about work after 1981 too. Thanks, Marko Amnell amnell(a)klaava.helsinki.fi ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

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mirror database for papers by ftp
by Paul Taylor 04 Mar '93

04 Mar '93

"mirror" DATABASE FOR PAPERS IN FTP ARCHIVES (1 March 1993) Thank you to those people who replied to Charles Wells' and my request for information about FTP archives of papers. He has handed his information over to me, and everything I have is in /theory/FTP-sites at theory.doc.ic.ac.uk Here again is my own entry in the database by way of a template. The meaning of the fields will be explained further down this message. package=TaylorP comment=Papers by Paul Taylor at Imperial site=theory.doc.ic.ac.uk remote_dir=/theory/papers/Taylor local_dir+papers/TaylorP # email=<pt(a)doc.ic.ac.uk> # phone=+44 71 589 5111 x 5057 # fax=+44 71 581 8024 # address=Dept of Computing, Imperial College, London SW7 2BZ, UK There follow some answers (not necessarily definitive) to some of the questions people have asked me about this. MACHINE READABLE. I would like to stress first the importance of observing the syntax. It is proposed that this database should be used by a program in batch mode, so if the syntax isn't right the program will choke - at night. Even when data is to be used by me as a human, I find it increasingly hard to keep track of its volume unless people make an effort to set apprpriate "Subject:" lines on their mail, keep information on one line, etc, so that I can use "grep" to search for things in my 6Mb of email per year. WHAT IS FTP? Having a personal FTP archive for your papers is like having a personal journal with no referees and immediate publication. This means that the constraints on publication, though very loose, are like those on publishers: if you make it hard for people to subscribe (eg by allowing your filespace to become disorganised or too large) then they'll stop. Subscribers can get single issues by manual interactive use of FTP, or standing orders by using the mirror program. MY SITE DOESN'T HAVE AN ARCHIVE. Then use someone else's. There are people from Cambridge, Darmstadt, Aarhus and other places who use the IC archive. WHAT'S THE DATABASE FOR? Even if automatic mirroring is not used, having a database in a machine readable format will make it much easier to find files. Maybe you will want to keep track of your immediate colleagues' work: in this case you can extract their entries from the database and set just those up to be mirrored. Although the information is of no use to the mirror program, this is also a sensible place to keep address information. A TYPICAL FTP SESSION. Here's how you can get my Cambridge PhD thesis, for example. machine% ftp theory.doc.ic.ac.uk Connected to beauty.doc.ic.ac.uk. 220 beauty FTP server (Version 6.14 Mon Nov 18 17:45:21 GMT 1991) ready. Name (theory.doc.ic.ac.uk:pt): anonymous ["ftp" will often do] 331 Guest login ok, send e-mail address as password. Password:pt@doc.ic.ac.uk 230-<some welcome message> 230-<put "-" at the beginning of your password> 230-<if these messages cause problems> 230- 230 Guest login ok, access restrictions apply. ftp> cd theory/papers/Taylor [set directory on remote machine] 250 CWD command successful. ftp> bin [binary mode for dvi (etc) files] 200 Type set to I. ftp> lcd ftp-imports/Taylor [set directory of your machine] ftp> hash [tells you how it's going] Hash mark printing on (8192 bytes/hash mark). ftp> get thesis.dvi [the file to fetch] 200 PORT command successful. 150 Opening BINARY mode data connection for thesis.dvi (907024 bytes). ##################### [five lines of these] 226 Transfer complete. local: thesis.dvi remote: thesis.dvi 907024 bytes received in 4.1 seconds (2.1e+02 Kbytes/s) ftp> quit 221 Goodbye. machine% WHAT ABOUT SOFTWARE? A lot of mirroring of software already goes on; for example the program which I propose to use was written to maintain a large archive of general software at Imperial (not to be confused with the TeX & Computing Theory archive which I maintain). For this reason I don't really consider it my job to get into the business of archiving software. Nevertheless, it does seem a good idea to add "papers/" to the local directory entries, so that there can also be a "software/" tree and a "conferences/" tree. CONFERENCE ANNOUNCEMENTS? It does seem reasonable to include those too, so I have added "papers/" to the local directory names for papers, so that we can have "conferences/" and "software/" too. Use the conference name where the author's name is appropriate for papers. JOINT PAPERS? Where do you put joint papers in your filing cabinet? I suggest choosing one of the authors, and then putting a cross reference (ie a short file which says "see BloggsJ for Bloggs & Smith") in the other directories. Personal bibliography databases should have complete entries under each individual author. If most of your work is done within a particular stable group, that can have an entry in the database as if it were a single person. ACCENTS & NAME CLASHES? It's not a good idea to use punctuation in filenames, or to make them too long. Clashes of both surname and initials within our community should be resolved by personal negotiation, ie agreeing to adopt initials, if necessary fictitious ones. Choose a mixed case alphabetic version of your surname and initials and stick to it. WHAT IS THE "mirror" PROGRAM? It was written by Lee McLoughlin in perl and uses the FTP protocol in much the same way as you would interactively, except that it's automatic and should be run outside the normal working hours of the sites concerned. You can get it from src.doc.ic.ac.uk as /packages/mirror/. It runs under Unix and is a bit shy of non-Unix FTP archives. Nevertheless, if some Unix site near you is maintaining an FTP archive of a wide range of papers and software, this is still of benefit to you even though you can't maintain your own copy on your non-Unix machine. HOW WILL THE DATA BE MAINTAINED? In the first instance I shall maintain it in the directory /theory/FTP-sites at theory.doc.ic.ac.uk. You may wish to mirror this directory, but I would advise against setting up anything too automatic for the time being. When I am satisfied that the database format is suitable and the data is correct for the mirror program, I shall ask the sites concerned to maintain their own databases, and use mirror to keep them up to date in my archive. In the long run, however, I think it would be better for each author to maintain this information in his/her own bibtex bibliography file (see /theory/bibliography/TaylorP.bib for instance) and then the mirror database can be extracted from this automatically. WHY THIS FORMAT? Per-author entries mean that you can mirror just the people you want rather than whole sites. As long as site managers make up their minds about directory names and stick to them, the information should only change radically when people move to other institutions (though phone extension numbers may change). It's sorted by site so that sites can maintain it and to make mirror/FTP mor efficient (it only logs in to each site once). A version sorted by author would be possible if someone wrote the program. Sorting by topic is completely impractical, though if people maintained their own bibtex files it would be possible to use "grep" to search by keyword. WHAT DO THE FIELDS MEAN? See "mirror" itself and the "defaults" at the end of the Imperial database for further explanation. "package" is a handle for the mirror program: you can ask it just to get a particular piece of software or, in this case, author's files. "comment" is copied to the mirror program log "site" is the Internet address of the FTP archive "remote_dir" is the directory on that archive "local_dir" is the directory into which you want to copy. I made a mistake in my original message: there should be a "+" instead of an "=". This means that this field is appended to the "local_dir" setting in the defaults so that you can set the root of your own archive (copy) tree as you think appropriate. Also, in order to allow conferences and software in the same databse, I've added "papers/" to these settings. The remaining fields are not recognised by "mirror" and so are commented out. "# email" is your email address in Internet format. Please put the actual address in angle brackets <> then you can add your name or whatever in front. "# phone" is your direct office phone number including extension and, where appropriate, secretary's name and extension. Please use international and not America format, for example London, New York and Paris are +4471, +1212 and +331 respectively, not 071, (212) or (1). "# fax" likewise. PLease specify if this is in a public area. "# address" postal address including country & code. Paul Taylor ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

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Two pages of Recoltes et Semailles
by cxm7＠pop.cwru.edu 03 Mar '93

03 Mar '93

------------- Can anyone send me a copy of pages 79 and 80 of Grothendieck's Recoltes et Semailles, premiere partie: Fatuite et Renouvellement? I would greatly appreciate it (and will forward a copy to David Feldman, who xeroxed his copy of F.et R. for me, but has these missing). Best regards, Colin McLarty Dept. of Philosophy Case Western Reserve Univ. Cleveland OH USA 44106 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

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note available by ftp
by dbenson%decserv2＠dns1.eecs.wsu.edu 01 Mar '93

01 Mar '93

The following short paper is available via ftp. The procedure follows the title and abstract Left Kan Extensions Over omega-Cat David B. Benson Electrical Engineering & Computer Science Washington State University Pullman, WA 99164-2752 dbenson(a)eecs.wsu.edu 1993 Feb 28 Abstract An existing procedure to compute left Kan extensions over the ground category Set also computes left Kan extensions over the ground categories Cat, 2-Cat, n-Cat for any n and indeed omega-Cat. Therefore extension data structured in this manner already can make use of the left Kan extension notion of a best possible approximation. Examples include systems of labeled transition systems and certain higher dimensional rewriting systems. -------------------- ftp ftp.eecs.wsu.edu login: anonymous password: <your email address> cd pub/papers/dbenson/kancat binary get Kan.dvi.Z (shortest file) -or- get Kan.dvi -or- get Kan.ps.Z -or- get Kan.ps (longest file) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

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