From MAILER-DAEMON Sat Oct 29 09:36:54 2005 Date: 29 Oct 2005 09:36:54 -0300 From: Mail System Internal Data Subject: DON'T DELETE THIS MESSAGE -- FOLDER INTERNAL DATA Message-ID: <1130589414@mta.ca> X-IMAP: 1128349647 0000000027 Status: RO This text is part of the internal format of your mail folder, and is not a real message. It is created automatically by the mail system software. If deleted, important folder data will be lost, and it will be re-created with the data reset to initial values. From rrosebru@mta.ca Mon Oct 3 11:14:47 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Mon, 03 Oct 2005 11:14:47 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EMR1Q-0006yI-Hw for categories-list@mta.ca; Mon, 03 Oct 2005 11:10:28 -0300 From: Colin McLarty To: categories@mta.ca Date: Sun, 02 Oct 2005 23:00:18 -0400 MIME-Version: 1.0 Content-Language: en Subject: categories: Phreilambud at Bowdoin 1969 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: 7bit Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: O X-Status: X-Keywords: X-UID: 1 I am interested in any stories about the 1969 Summer Institute at Bowdoin. Who was there? In particular,the Reports of the Midwest Category Seminar IV (SLN 137) has a humor piece written as a ``final exam'' for the Institute. It is signed ``Phreilambud.'' Who is this? I can make it up out of various people's names, but I don't know who was there. Colin From rrosebru@mta.ca Mon Oct 3 16:54:10 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Mon, 03 Oct 2005 16:54:10 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EMWDu-000606-Jc for categories-list@mta.ca; Mon, 03 Oct 2005 16:43:42 -0300 Message-ID: <434144AE.9090306@inf.u-szeged.hu> Date: Mon, 03 Oct 2005 16:48:14 +0200 From: Computer Science Logic '06 Conference User-Agent: Mozilla Thunderbird 1.0 (Windows/20041206) X-Accept-Language: en-us, en MIME-Version: 1.0 To: categories@mta.ca Subject: categories: CSL'06 workshops and Ackermann Award Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: X-Keywords: X-UID: 2 ------------------------------------------------------------------- CSL 2006 Call For Workshop Proposals ------------------------------------------------------------------- Computer Science Logic (CSL) is the annual conference series of the European Association for Computer Science Logic (EACSL). The 15th Annual Conference, CSL 2006, will take place in Szeged, Hungary, from September 25 to September 29, 2006. It will be organized by the Department of Foundations of Computer Science at the University of Szeged. Workshops affiliated to CSL 2006 will be held before and after the main conference, on September 23 and 24, and on September 30 and October 1, 2006. Researchers and practitioners are invited to submit proposals for workshops on topics relating logic to computer science. Proposals should include: * A short scientific summary and justification of the proposed topic. * Proposed format and agenda. * Proposed duration. * Procedures for selecting participants and papers. * Expected number of participants. * Potential invited speakers. * Plans for dissemination (e.g. proceedings, journal special issue). Workshop organizers are expected to be present during their workshops. Full proposals are due November 15, 2005 and will be evaluated by the CSL 2006 Workshop Committee on the basis of their assessed benefit for prospective participants of CSL 2006. Acceptance decisions will be made by December 1, 2005. The members of the Workshop Committee are: Matthias Baaz (Vienna), Damian Niwinski (Warsaw) and Sandor Vagvolgyi (Szeged, chair). Proposals and/or enquiries should be submitted by electronic mail in ASCII, PDF or postscript format to: Sandor Vagvolgyi CSL 2006 Workshop Chair Email: vagvolgy at inf.u-szeged.hu The titles and brief information related to accepted workshop proposals will be included in the conference program and advertised in the Call for Participation. Workshop organizers will be responsible for producing a Call for Papers, web site, reviewing and making acceptance decisions on submitted papers, collecting funds for invited speakers, and scheduling workshop activities in consultation with the local organizers. Important dates : November 15, 2005: Workshop proposals December 1, 2005: Acceptance decisions CSL 2006 Web site: http://www.inf.u-szeged.hu/~csl06/ ------------------------------------------------------------------- AA06 ------------------------------------------------------------------- Ackermann Award 2006 --------------------- Nominations are solicted for the Ackermann Award 2006. The EACSL Outstanding Dissertation Award for Logic in Computer Science (The Ackermann Award) will be presented to the recipients at the annual conference of the EACSL (CSL'06). The jury is entitled to give more than one award per year. The first Ackermann Award was presented at CSL'05. The 2005 recipients were Mikolaj Bojanczyk Konstantin Korovin Nathan Segerlind Eligible for the 2006 Ackermann Award are PhD dissertations in topics specified by the EACSL and LICS conferences, which were formally accepted as PhD theses at a university or equivalent institution between 1.1.2004 and 31.12. 2005. ----------------------------------------- The deadline for submission is 31.1.2006. ----------------------------------------- Submission details are available at www.dimi.uniud.it/~eacsl/award.html www.cs.technion.ac.il/eacsl The award consists of * a diploma, * an invitation to present the thesis at the CSL conference, * the publication of the abstract of the thesis and the laudation in the CSL proceedings, * travel support to attend the conference. The jury consists of seven members: * The president of EACSL, J. Makowsky (Haifa); * The vice-president of EACSL, D. Niwinski (Warsaw); * One member of the LICS organizing committee, S. Abramnsky (Oxford); * B. Courcelle (Bordeaux); * E. Graedel (Aachen); * M. Hyland (Cambridge); * A. Razborov (Moscow and Princeton). From rrosebru@mta.ca Mon Oct 3 16:54:10 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Mon, 03 Oct 2005 16:54:10 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EMWFu-0006At-HJ for categories-list@mta.ca; Mon, 03 Oct 2005 16:45:46 -0300 Date: Mon, 3 Oct 2005 11:58:38 -0400 (EDT) From: Peter Freyd Message-Id: <200510031558.j93Fwc1Q018960@saul.cis.upenn.edu> To: categories@mta.ca Subject: categories: Re: Phreilambud at Bowdoin 1969 Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: X-Keywords: X-UID: 3 ``Phreilambud'' was written by me, a young student named Lambert who disappeared, I think, from mathematics and David Eisenbud, now paying for his sins as head of MSRI (Berkeley). Peter From rrosebru@mta.ca Mon Oct 3 16:54:11 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Mon, 03 Oct 2005 16:54:11 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EMWGd-0006Ei-Qo for categories-list@mta.ca; Mon, 03 Oct 2005 16:46:31 -0300 Date: Mon, 3 Oct 2005 10:37:29 -0700 (PDT) From: John MacDonald To: categories@mta.ca Subject: categories: Re: Phreilambud at Bowdoin 1969 In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: X-Keywords: X-UID: 4 This is from memory so there could be some inaccuracies. I first met John Isbell there since I shared office space with him. He said that he saw no need to get a room since he could just sleep in the office. Peter Freyd's daughters babysat my daughter Eleanor, aged 2, and son Lauchlin, aged 2 months and my first wife Dorinne often spoke with Pam. Phreilambud included David Eisenbud for sure, and possibly Eilenberg, Freyd and others. John On Sun, 2 Oct 2005, Colin McLarty wrote: > I am interested in any stories about the 1969 Summer Institute at > Bowdoin. Who was there? > > In particular,the Reports of the Midwest Category Seminar IV (SLN 137) > has a humor piece written as a ``final exam'' for the Institute. It is > signed ``Phreilambud.'' Who is this? I can make it up out of various > people's names, but I don't know who was there. > > Colin > > > From rrosebru@mta.ca Mon Oct 3 16:54:11 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Mon, 03 Oct 2005 16:54:11 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EMWF7-00065N-2y for categories-list@mta.ca; Mon, 03 Oct 2005 16:44:57 -0300 Mime-Version: 1.0 (Apple Message framework v733) From: Marco Grandis Subject: Categories: Re: Name of concept? Date: Mon, 3 Oct 2005 17:15:27 +0200 To: categories@mta.ca Content-Transfer-Encoding: 7bit Content-Type: text/plain;charset=US-ASCII;delsp=yes;format=flowed Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: RO X-Status: X-Keywords: X-UID: 5 Yes, I like this symmetric presentation. ____ As to "Notice..." (where you mean ... meet im(d), of course), I would add the following. The condition dd = 0 is linked with aspects whose relevance is often ignored. Without it, many systems of use in homological algebra would loose any reasonable notion of "canonical isomorphism", and one should be extremely prudent in working with induced morphisms and Noether isomorphisms. Let us start (in Ab, or any abelian category) with a sublattice L of subobjects of a given object (necessarily modular) and consider the subquotients having numerator and denominator in L. Then, the canonical isomorphisms among these subquotients (induced by the identity) are closed under composition *if and only if* L is distributive. - Within this restriction, being "canonically isomorphic subquotients" has a precise meaning: there is a well-determined canonical isomorphism linking them. - Without this restriction, composing canonical isomorphisms can yield different isomorphisms between two given subquotients. Working up to canonical isomorphism, as commonly done in homological algebra, could easily lead to errors. (For instance, it is easy to construct such a situation for subquotiens of Z^2 (pairs of integers) in Ab - the classical example of an object whose lattice of subobjects is not distributive.) Concretely, the main systems of homological algebra giving rise to spectral sequences (filtered differential object, filtered complex, exact pairs, double complex) DO produce distributive lattices. Essentially, the proof is generally based on a crucial Birkoff theorem: the free modular lattice generated by two chains is distributive. But all this is no longer true without assuming dd = 0 (or something similar) in such systems: distributivity would fail. [[ It is easy to see the role of dd = 0 in the simplest case, the filtered differential object. We have a differential object (A, d) equipped with a consistent filtration (F_p A), so that every d(F_p A) is contained in F_p A. Then, one can prove that the sublattice of Sub(A) generated by the filtration and closed under d-images and d-preimages (written d*) is generated by two filtrations, the original one and 0 -> ... d(F_p A) ... -> dA -> d*0 -> ... d*(F_p A) ... -> A, using the inclusion dA -> d*0. ]] Zeeman was probably the first to recognise the importance of this fact: E.C. Zeeman, On the filtered differential group, Ann. Math. 66 (1957), 557-585. _____ The theory I am referring to can be seen in three papers of mine: M.G., On distributive homological algebra, I-III, Cahiers 25 (1984), 259-301; 25 (1984), 353-379; 26 (1985), 169-213. Recently, Francis Borceux and I have extended part of these results to a larger setting, including Grp (groups): F. Borceux - M. Grandis, Jordan-Holder, modularity and distributivity in non-commutative algebra, Dip. Mat. Univ. Genova, Preprint 474 (Feb 2003). http://www.dima.unige.it/~grandis/BGwe.dvi Marco Grandis On 30 Sep 2005, at 20:37, Michael Barr wrote: Incidentally, did you know that if Z and Z' are defined so that a d a' 0 --> Z ---> C ---> C ---> Z' ---> 0 is exact, then the homology is the image (= coimage) of a'.a: Z --> Z'? This is a triviality, but it gives a symmetric definition of homology. Notice that it defines something even when d.d is not 0. I guess it is Z mod Z meet ker(d). Mike From rrosebru@mta.ca Mon Oct 3 21:27:04 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Mon, 03 Oct 2005 21:27:04 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EMaa0-0000bf-2l for categories-list@mta.ca; Mon, 03 Oct 2005 21:22:48 -0300 Message-ID: <007d01c5c853$eb6d8070$9800a8c0@david> From: "David Ellerman" To: References: Subject: categories: Re: Phreilambud at Bowdoin 1969 Date: Mon, 3 Oct 2005 12:51:59 -0700 MIME-Version: 1.0 Content-Type: text/plain;format=flowed;charset="iso-8859-1";reply-type=original Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 Sender: cat-dist@mta.ca Precedence: bulk Status: RO X-Status: X-Keywords: X-UID: 6 I attended the Bowdoin Summer Seminar as a 2nd year math grad student with some training in math logic and none in category theory. MacLane gave the principal lectures (later developed into his CWM) and others (Eilenberg, Isbell) weighed in with lectures on special topics. A few points stick in memory. For instance, Eilenberg lectured on his categorical treatment of abstract machine theory. At one point he was analyzing the words generated by a set of symbols A, and he derived that I+A+A^2+... = [I-A]^-1 with such flourish that a spontaneous applause broke out in the audience. Otherwise, Eilenberg along with Lawvere and Tierney played poker and smoked cigars with great relish. In one lecture on some of Linton's results, MacLane presented a picture of an Australian road sign for the town of "Colinton" which MacLane said was named after Linton's antipodal dual. Foreign (i.e., non-North-American) category theorists were represented by (at least) Eduardo Dubuc and Sabah Fakir. I don't know about "Phreilambud" but I suspect the "bud" is from Eisenbud who mentions in his Preface to MacLane's mathematical autobiography that Bowdoin was the only time he saw "Saunders and Sammy" together and that all gathered around when they discussed the origins of the subject one evening after dinner. These were early days in the so-called 'foundations' debate with set theory where the latter was represented at Bowdoin by Feferman. I suspect that many of the arguments expressed in Feferman's 1977 article (which Colin recently described as "the most sustained critique of categorical foundations to date" [Phil. Math. 2005]) were hammered out at Bowdoin. The last session of the seminar was called the "prayer meeting" where various people were asked to "let their hair down" and talk informally about the future of CT and foundations. I was the symbolic grad student asked to say a few words and I was so nervous I don't remember what the others said! I made a few (certainly elementary and perhaps incoherent) remarks on the difference between sets as (non-self-participating) universals for a property in contrast with the (self-participating) universals (UMPs) of CT which in some sense exemplify the property they represent (ideas developed years later in an article on "concrete universals" and CT in Erkenntnis 1988). The final social event was a feast of Maine lobsters at a nearby beach presided over by MacLane and Dorothy. As we were devouring our lobsters, I particularly remember MacLane shouting out to all assembled: "Don't eat the green stuff, don't eat the green stuff!" (a reference to lower part of the lobster's alimentary canal). _____________________ David Ellerman Visiting Scholar University of California at Riverside Mailing address: 4044 Mt Vernon Ave Riverside, CA 92507 Email: david@ellerman.org Webpage: www.ellerman.org View my research on my SSRN Author page: http://ssrn.com/author=294049 ----- Original Message ----- From: "Colin McLarty" To: Sent: Sunday, October 02, 2005 8:00 PM Subject: categories: Phreilambud at Bowdoin 1969 >I am interested in any stories about the 1969 Summer Institute at > Bowdoin. Who was there? > > In particular,the Reports of the Midwest Category Seminar IV (SLN 137) > has a humor piece written as a ``final exam'' for the Institute. It is > signed ``Phreilambud.'' Who is this? I can make it up out of various > people's names, but I don't know who was there. > > Colin > From rrosebru@mta.ca Tue Oct 4 12:04:53 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Tue, 04 Oct 2005 12:04:53 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EMoJ2-0006Ue-So for categories-list@mta.ca; Tue, 04 Oct 2005 12:02:13 -0300 Message-ID: <43426ABC.2030700@cs.stmarys.ca> Date: Tue, 04 Oct 2005 08:42:52 -0300 From: "Robert J. MacG. Dawson" User-Agent: Mozilla Thunderbird 1.0.2 (Windows/20050317) X-Accept-Language: en-us, en MIME-Version: 1.0 To: categories@mta.ca Subject: categories: Re: Phreilambud at Bowdoin 1969 References: <007d01c5c853$eb6d8070$9800a8c0@david> In-Reply-To: <007d01c5c853$eb6d8070$9800a8c0@david> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Checker-Version: SpamAssassin 3.0.4 (2005-06-05) on mx1.mta.ca X-Spam-Level: X-Spam-Status: No, score=0.1 required=5.0 tests=FORGED_RCVD_HELO autolearn=disabled version=3.0.4 Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: X-Keywords: X-UID: 7 David Ellerman wrote: > The final social event was a feast of Maine lobsters at a nearby beach > presided over by MacLane and Dorothy. As we were devouring our lobsters, I > particularly remember MacLane shouting out to all assembled: "Don't eat the > green stuff, don't eat the green stuff!" (a reference to lower part of the > lobster's alimentary canal). The "green stuff" is not the lower part of the lobster's alimentary canal (a barely visible black "string"); it is the lobster's liver. While the texture & flavor take more getting used to than those of the white meat, the liver (known slightly confusingly as "tomalley") is perfectly wholesome, and should certainly be eaten. So, of course, should the immature eggs (bright red & known as "coral") if present. -Robert Dawson From rrosebru@mta.ca Tue Oct 4 12:04:53 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Tue, 04 Oct 2005 12:04:53 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EMoHI-0006Mb-Lk for categories-list@mta.ca; Tue, 04 Oct 2005 12:00:24 -0300 References: Mime-Version: 1.0 (Apple Message framework v733) X-Priority: 3 Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Message-Id: <16659D0E-8A3E-4D49-9178-E5DC5002D09C@math.mq.edu.au> Content-Transfer-Encoding: 7bit From: Ross Street Subject: categories: Re: Phreilambud at Bowdoin 1969 Date: Tue, 4 Oct 2005 11:27:35 +1000 To: X-Mailer: Apple Mail (2.733) X-Spam-Checker-Version: SpamAssassin 3.0.4 (2005-06-05) on mx1.mta.ca X-Spam-Level: X-Spam-Status: No, score=0.0 required=5.0 tests=none autolearn=disabled version=3.0.4 Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: X-Keywords: X-UID: 8 > a picture of an Australian road sign for the town of "Colinton" which > MacLane said was named after Linton's antipodal dual. Foreign (i.e., > non-North-American) category theorists were represented by (at least) > Eduardo Dubuc and Sabah Fakir. Presumably I was considered North American at the time as the Bowdoin Seminar came between a postdoc at U Illinois (Champ-Urb) and a assistant professorship at Tulane. Sammy commented that I began the summer as an Australian and ended up an all American boy. Sammy was prone to exaggeration. I have wonderful memories of that summer: Mac Lane's incredible lectures (every morning -- 2 hours I think -- for the whole summer), freezing water at the beach although the weather was hot, the "pro-seminars" run by new postdocs that were organized after Mac Lane's first lecture, becoming marooned when the tide came in and Eduardo Dubuc (up to his chest in water) carried Joan Machez (sp?) while I supported her broken leg in its cast, the tall dormitory with 16 bedrooms per level and Sammy at the top in the penthouse, that clam and lobster bake, buying beer at the supermarket where the under-aged checkout girl had to get an older person to punch in the price of the beer! and many other things mathematical and non. Mac Lane, Dubuc, Duskin and I moved down to Tulane after that for its "Year on Category Theory 1969-70". --Ross From rrosebru@mta.ca Tue Oct 4 12:04:53 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Tue, 04 Oct 2005 12:04:53 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EMoIH-0006R3-Go for categories-list@mta.ca; Tue, 04 Oct 2005 12:01:25 -0300 Mime-Version: 1.0 (Apple Message framework v622) To: categories@mta.ca Message-Id: <20d4094d36b3d9761f700b750f35697d@di.uminho.pt> Content-Type: multipart/mixed; boundary=Apple-Mail-11--214302673 From: Luis Barbosa Subject: categories: FACS'05: Call for Participation Date: Tue, 4 Oct 2005 10:05:52 +0100 Content-Transfer-Encoding: 7bit Content-Type: text/plain;charset=US-ASCII;delsp=yes;format=flowed Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: X-Keywords: X-UID: 9 [apologies for cross-posting] ------------------------------------------------------------------------ - Please find attached the Call for Participation on FACS'05 2nd International Workshop on Formal Aspects of Component Software to be held at UNU-IIST, Macao, 24-25, October, 2005. The workshop programme, on-line registration and further information on travel and accommodation is available from www.iist.unu.edu/facs05/ From rrosebru@mta.ca Wed Oct 5 11:40:59 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Wed, 05 Oct 2005 11:40:59 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1ENALc-0004Ty-Fp for categories-list@mta.ca; Wed, 05 Oct 2005 11:34:20 -0300 Message-ID: <4343A71F.3050901@mcs.le.ac.uk> Date: Wed, 05 Oct 2005 11:12:47 +0100 From: Alexander Kurz User-Agent: Debian Thunderbird 1.0.2 (X11/20050817) X-Accept-Language: en-us, en MIME-Version: 1.0 To: categories@mta.ca Subject: categories: PhD Studentship available References: <42AF4D88.50505@mcs.le.ac.uk> In-Reply-To: <42AF4D88.50505@mcs.le.ac.uk> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: X-Keywords: X-UID: 10 Apologies for multiple postings ------------------------------- Please distribute to potential candidates ----------------------------------------- Recently, I advertised a postdoc position on the EPSRC-funded project "Coalgebras, Modal Logic, Stone Duality". Additionally, there is now a departmentally funded PhD studentship (GTA) available. The GTA scheme involves some teaching and runs for 4 years. Unfortunately, the position is probably only of interest to students with an EU nationality: the university seems to be unwilling to waive the fees for non-EU nationals. The topic of the PhD will be in the area of "Coalgebras, Modal Logic, Stone Duality". Repeating from my previous mail: >From the point of view of computer science, the project is about logics for transition systems (coalgbras). From the mathematical point of view, the project will explore the dualities arising from extending basic, Stone-type dualities via an algebra-coalgebra duality. This draws on results and concepts from modal logic, domain theory, universal algebra and category theory. A background in one (or more) of the above areas is desirable. The official announcement and application form is available at (Ref E2275) http://www.le.ac.uk/personnel/jobs/a&r.html The applications should be submitted no later than 18 October 2005. If you have any questions please contact me via email. Best wishes, Alexander From rrosebru@mta.ca Wed Oct 5 11:40:59 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Wed, 05 Oct 2005 11:40:59 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1ENAKU-0004JW-BL for categories-list@mta.ca; Wed, 05 Oct 2005 11:33:10 -0300 Message-ID: <4343A79E.7080409@bangor.ac.uk> Date: Wed, 05 Oct 2005 11:14:54 +0100 From: Tim Porter User-Agent: Mozilla/5.0 (Windows; U; Win98; en-US; rv:1.4) Gecko/20030624 Netscape/7.1 (ax) X-Accept-Language: en, en-us, fr MIME-Version: 1.0 To: categories@mta.ca Subject: categories: New and newish Bangor preprints. Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: X-Keywords: X-UID: 11 Dear all, Some of you may be interested in some recent preprints from us at bangor http://www.informatics.bangor.ac.uk/public/mathematics/research/preprints/05/05prep.html HEALTH WARNING As usual these are still drafts so may change. They even might contain errors! I will put some of them on the Arxiv later on when I have a bit of time. Tim From rrosebru@mta.ca Thu Oct 6 16:28:39 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Thu, 06 Oct 2005 16:28:39 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1ENbIz-0004tE-57 for categories-list@mta.ca; Thu, 06 Oct 2005 16:21:25 -0300 X-Authentication-Warning: triples.math.mcgill.ca: barr owned process doing -bs Date: Thu, 6 Oct 2005 11:56:30 -0400 (EDT) From: Michael Barr X-X-Sender: barr@triples.math.mcgill.ca To: Categories list Subject: categories: preserving homology Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: cat-dist@mta.ca Precedence: bulk Status: RO X-Status: X-Keywords: X-UID: 12 At my ftp site ftp.math.mcgill.ca/pub/barr/pdffiles is a note called preservinghomology.pdf that raises (but does not satisfactorily answer) the question of what it means for an additive functor between abelian categories to preserve homology. It does work for functors that are either right or left exact. If anyone has solved (or even looked seriously at the question) I would appreciate hearing from them. Michael From rrosebru@mta.ca Mon Oct 10 12:43:49 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Mon, 10 Oct 2005 12:43:49 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EOzhY-0003jR-N8 for categories-list@mta.ca; Mon, 10 Oct 2005 12:36:32 -0300 Date: Mon, 10 Oct 2005 04:42:13 -0700 (PDT) Message-Id: <200510101142.j9ABgDpx004565@fast.ucsd.edu> From: Joseph Goguen To: categories@mta.ca Subject: categories: Re: Phreilambud at Bowdoin 1969 X-Spam-Flag: Spam NO Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: X-Keywords: X-UID: 13 Hi Colin, I was there as a freshly minted PhD about to go to my first academic job at University of Chicago. What i most vividly remember was Eilenberg, sitting in the center near the front, constantly asking smart questions, which did not necessarily help the speaker; and in particular, of course, i remember this during my talk on automata and recursion in cartesian closed categories. Frankly, i was a bit shocked at the level of competitiveness that i felt in the institute, no doubt my naivety showing, after spending laid back years at Berkeley. Joseph Goguen > From: Colin McLarty > Date: Sun, 02 Oct 2005 23:00:18 -0400 > Content-Language: en > Content-Disposition: inline > Precedence: bulk > X-Greylisting: NO DELAY (Relay+Sender autoqualified); > processed by UCSD_GL-v2.1 on mailbox6.ucsd.edu; > Mon, 03 October 2005 07:27:33 -0700 (PDT) > X-Spam-Level: Level > X-Spamscanner: mailbox6.ucsd.edu (v1.6 Aug 4 2005 15:27:38, -2.6/5.0 3.0.4) > X-MailScanner: PASSED (v1.2.8 22150 j93ERW3p026939 mailbox6.ucsd.edu) > X-Spam-Flag: Spam NO > X-Scanned-By: milter-spamc/0.15.245 (fast.ucsd.edu [132.239.15.4]); pass=YES; Mon, 03 Oct 2005 07:27:36 -0700 > X-Spam-Status: NO, hits=-0.80 required=5.00 > > I am interested in any stories about the 1969 Summer Institute at > Bowdoin. Who was there? > > In particular,the Reports of the Midwest Category Seminar IV (SLN 137) > has a humor piece written as a ``final exam'' for the Institute. It is > signed ``Phreilambud.'' Who is this? I can make it up out of various > people's names, but I don't know who was there. > > Colin > From rrosebru@mta.ca Tue Oct 11 08:22:23 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Tue, 11 Oct 2005 08:22:23 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EPI8c-000043-KR for categories-list@mta.ca; Tue, 11 Oct 2005 08:17:42 -0300 Message-ID: <1129019359.434b77df950e3@mail.inf.ed.ac.uk> Date: Tue, 11 Oct 2005 09:29:19 +0100 From: ajp@inf.ed.ac.uk To: cmcs06@cs.nott.ac.uk Subject: CMCS 2006 MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit User-Agent: Internet Messaging Program (IMP) 3.2.3 Sender: cat-dist@mta.ca Precedence: bulk Status: RO X-Status: X-Keywords: X-UID: 14 CMCS 2006 8th International Workshop on Coalgebraic Methods in Computer Science http://conferences.inf.ed.ac.uk/cmcs06/cmcs06.html Vienna, Austria March 25-27, 2006 The workshop will be held in conjunction with the 9th European Joint Conferences on Theory and Practice of Software ETAPS 2006 March 25 - April 2, 2006 Aims and Scope During the last few years, it has become increasingly clear that a great variety of state-based dynamical systems, like transition systems, automata, process calculi and class-based systems, can be captured uniformly as coalgebras. Coalgebra is developing into a field of its own interest presenting a deep mathematical foundation, a growing field of applications and interactions with various other fields such as reactive and interactive system theory, object oriented and concurrent programming, formal system specification, modal logic, dynamical systems, control systems, category theory, algebra, analysis, etc. The aim of the workshop is to bring together researchers with a common interest in the theory of coalgebras and its applications. The topics of the workshop include, but are not limited to: the theory of coalgebras (including set theoretic and categorical approaches); coalgebras as computational and semantical models (for programming languages, dynamical systems, etc.); coalgebras in (functional, object-oriented, concurrent) programming; coalgebras and data types; (coinductive) definition and proof principles for coalgebras (with bisimulations or invariants); coalgebras and algebras; coalgebraic specification and verification; coalgebras and (modal) logic; coalgebra and control theory (notably of discrete event and hybrid systems). The workshop will provide an opportunity to present recent and ongoing work, to meet colleagues, and to discuss new ideas and future trends. Previous workshops of the same series have been organized in Lisbon, Amsterdam, Berlin, Genova, Grenoble, Warsaw and Barcelona. The proceedings appeared as Electronic Notes in Theoretical Computer Science (ENTCS) Volumes 11,19, 33, 41, 65.1, 82.1 and 106. You can get an idea of the types of papers presented at the meeting by looking at the tables of contents of the ENTCS volumes from those workshops ENTCS Location CMCS 2006 will be held in Vienna on March 25-27, 2006. It will be a satellite workshop of ETAPS 2006, the European Joint Conferences on Theory and Practice of Software. Programme Committee John Power (chair,Edinburgh), Luis Barbosa (Minho), Neil Ghani (Nottingham), H. Peter Gumm (Marburg), Marina Lenisa (Udine), Stefan Milius (Braunschweig), Larry Moss (Bloomington), Jan Rutten (Amsterdam), Hendrik Tews (Dresden), Tarmo Uustalu (Tallinn), Hiroshi Watanabe (Osaka). Keynote Speaker: Peter O'Hearn (Queen Mary, University of London) Invited Speakers: Corina Cirstea (University of Southampton) Alexander Kurz (University of Leicester) Submissions Two sorts of submissions will be possible this year: Papers to be evaluated by the programme committee for inclusion in the ENTCS proceedings: These papers must be written using ENTCS style files and be of length no greater than 20 pages. They must contain original contributions, be clearly written, and include appropriate reference to and comparison with related work. If a submission describes software, software tools, or their use, it should include all source code that is needed to reproduce the results but is not publicly available. If the additional material exceeds 5 MB, URL's of publicly available sites should be provided in the paper. Short contributions: These will not be published but will be compiled into a technical report of the University of Nottingham. They should be no more than two pages and may describe work in progress, summarise work submitted to a conference or workshop elsewhere, or in some other way appeal to the CMCS audience. Both sorts of submission should be submitted in postscript or pdf form as attachments to an email to cmcs06@cs.nott.ac.uk. The email should include the title, corresponding author, and, for the first kind of submission, a text-only one-page abstract. After the workshop, we expect to produce a journal proceedings of extended versions of selected papers to appear in Theoretical Computer Science. Important Dates Deadline for submission of regular papers: January 8, 2006. Notification of acceptance of regular papers: February 6, 2006. Final version for the preliminary proceedings: February 13, 2006. Deadline for submission of short contributions: February 28, 2006. Notification of acceptance of short contributions: March 6, 2006. For more information, please write to cmcs06@cs.nott.ac.uk. From rrosebru@mta.ca Wed Oct 12 14:28:09 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Wed, 12 Oct 2005 14:28:09 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EPkGA-00004R-Ul for categories-list@mta.ca; Wed, 12 Oct 2005 14:19:22 -0300 Date: Tue, 11 Oct 2005 11:30:37 -0400 (EDT) From: Richard Blute To: categories@mta.ca Subject: categories: Octoberfest schedule Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: cat-dist@mta.ca Precedence: bulk Status: RO X-Status: X-Keywords: X-UID: 15 The final schedule for Octoberfest '05 is now available, and can be found on the website: http://aix1.uottawa.ca/~scpsg/Octoberfest05/Octoberfest.final1.htm As you can see, we have a busy schedule. Rather than having a banquet, we will provide lunch on both Saturday and Sunday. Ottawa has many fine restaurants for dinner, and a dining guide will be provided. As is traditional for Octoberfest, we have managed to keep costs to a minimum. Registration will be 25 dollars, and students may attend for free. We remind you that if you need parking for the weekend, you must contact us right away. Look forward to seeing you all soon, Rick Blute Phil Scott -- From rrosebru@mta.ca Sat Oct 15 10:35:04 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Sat, 15 Oct 2005 10:35:04 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EQm3M-0000Ow-2C for categories-list@mta.ca; Sat, 15 Oct 2005 10:26:24 -0300 Date: Sat, 15 Oct 2005 08:10:14 +0200 From: Santocanale Luigi User-Agent: Mozilla Thunderbird 1.0.2 (X11/20050317) X-Accept-Language: fr, en MIME-Version: 1.0 To: categories@mta.ca Subject: categories: GEOMETRY OF COMPUTATION 2006 (Geocal06) Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: O X-Status: X-Keywords: X-UID: 16 Apologies for multiple posting. Remark: deadline for preregistration: 30 October 2005 ----------------------------------------------------------------------- SECOND ANNOUNCEMENT AND CALL FOR PARTICIPATION TO THE SESSION GEOMETRY OF COMPUTATION 2006 (Geocal06) Monday January 30 - Friday March 3 CIRM(1), Luminy, Marseille, France INFORMATION AND PREREGISTRATION ON http://iml.univ-mrs.fr/geocal06/ PREREGISTRATION WILL BE CLOSED ON Sunday October 30th 2005 The session is organised by the GEOCAL(2) project and intends to gather researchers interested in various topics of theoretical computer science including logic, realisability, algorithmic complexity, semantics of programming languages, algebraic methods for concurrency, probabilistic transition systems, modelisation of biological networks... The session will consist of a series of events: 4 winter school lectures during the first 2 weeks followed by 9 thematic workshops. A detailed description including a provisional programme and the preregistration form are available on the Geocal06 home page(3). Participants will lodge at the CIRM(1). There is no registration fee but = the CIRM will charge about 65 euros a day for a full board stay. A number of fundings for students will be available as well. If you would like to participate to one ore more events, please fill in the form before October 30th. Note that there is a large but finite number of places at the CIRM; in case we have too many preregistrations for the same period, late ones will be canceled. Thomas Ehrhard and Laurent Regnier Institut de Math=E9matiques de Luminy ------------------------------------------ (1) http://www.cirm.univ-mrs.fr/ (2) http://iml.univ-mrs.fr/~ehrhard/geocal/ (3) http://iml.univ-mrs.fr/geocal06/ From rrosebru@mta.ca Wed Oct 19 11:30:25 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Wed, 19 Oct 2005 11:30:25 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1ESEpi-0007k7-DG for categories-list@mta.ca; Wed, 19 Oct 2005 11:22:22 -0300 Date: Tue, 18 Oct 2005 16:30:33 +0100 From: Corina Cirstea Organization: University of Southampton User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7a) Gecko/20040219 X-Accept-Language: en-us, en MIME-Version: 1.0 To: categories@mta.ca Subject: categories: Research position in Coalgebras and Formal Verification at Southampton Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: O X-Status: X-Keywords: X-UID: 17 *Research position in Coalgebras and Formal Verification* School of Electronics and Computer Science University of Southampton Declarative Systems and Software Engineering Group http://www.dsse.ecs.soton.ac.uk Closing date: 31 October 2005 Applications are invited for a Research Fellow in the Declarative=20 Systems and Software Engineering Group, in the School of Electronics and=20 Computer Science. The School is the largest of its kind in the UK, and=20 has internationally acknowledged research excellence in Electronics and=20 Computer Science (RAE 2001 Grade 5*/5*). The successful applicant will work on the EPSRC-funded research project=20 "Towards a Modular Approach to Model-Based Verification: logical,=20 semantical and algorithmic support". The project aims to develop modular=20 model-based verification techniques for state-based dynamical systems,=20 by using the mathematical theory of coalgebras as a unifying framework. Applicants should have (or be nearing the completion of) a PhD in=20 Computer Science or a related subject, and have a proven research record=20 in theoretical computer science/formal methods. Experience in one or=20 more of the following areas: logic, universal coalgebra, category=20 theory, formal specification, model checking is desirable. The salary=20 will be in the range =A322,774 - =A328,009. The post is available for two= =20 years, from 01/01/2006. Informal enquiries should be addressed to Dr Corina C=EErstea, Tel: +44=20 (0)23 8059 3625, e-mail: cc2@ecs.soton.ac.uk. An application form and further particulars may be obtained from the=20 Human Resources Department (R), University of Southampton, Highfield,=20 Southampton, SO17 1BJ, Tel: 023 8059 2750, e-mail: recruit@soton.ac.uk=20 or minicom: 023 8059 5595, alternatively visit our website at=20 www.jobs.soton.ac.uk. Closing date for applications 31/10/2005. Please=20 quote reference number 05R0160C. ----------------------------------------------------------------------- Dr Corina Cirstea Electronics and Computer Science University of Southampton Southampton, SO17 1BJ United Kingdom Tel: +44 (0)23 8059 3625 ----------------------------------------------------------------------- From rrosebru@mta.ca Thu Oct 20 17:30:29 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Thu, 20 Oct 2005 17:30:29 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1ESgxS-0007gd-AT for categories-list@mta.ca; Thu, 20 Oct 2005 17:24:14 -0300 Date: Thu, 20 Oct 2005 10:52:05 -0400 (EDT) From: Peter Freyd Message-Id: <200510201452.j9KEq5h6018666@saul.cis.upenn.edu> To: categories@mta.ca Subject: categories: Ottawa weather Sender: cat-dist@mta.ca Precedence: bulk Status: RO X-Status: X-Keywords: X-UID: 18 Friday Scattered Clouds. High: 48F / 9C Wind WNW 4 mph / 7 km/h Friday Night Scattered Clouds. Low: 30F / -1C Wind North 4 mph / 7 km/h Saturday Scattered Clouds. High: 51F / 11C Wind NE 6 mph / 10 km/h Saturday Night Scattered Clouds. Low: 32F / 0C Wind NE 8 mph / 14 km/h Sunday Scattered Clouds. High: 48F / 9C Wind NE 15 mph / 25 km/h Sunday Night Rain. Low: 37F / 3C Wind ENE 15 mph / 25 km/h Monday Overcast. High: 41F / 5C Wind ENE 13 mph / 21 km/h From rrosebru@mta.ca Mon Oct 24 10:29:28 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Mon, 24 Oct 2005 10:29:28 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EU2Go-0001wb-Us for categories-list@mta.ca; Mon, 24 Oct 2005 10:21:46 -0300 Date: Fri, 21 Oct 2005 09:26:48 +0200 To: event@in.tu-clausthal.de Message-ID: <20051021072648.GY24862@in.tu-clausthal.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline From: event@mail.in.tu-clausthal.de Subject: categories: FM'06: CFP Reply-To: event-owner@in.tu-clausthal.de Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: X-Keywords: X-UID: 19 ========================================================================= FM'06: 14TH INTERNATIONAL SYMPOSIUM ON FORMAL METHODS 21 - 27 August 2006 McMaster University, Hamilton, Ontario, Canada http://fm06.mcmaster.ca/ ANNOUNCEMENT AND CALL FOR SUBMISSIONS FM'06 is the fourteenth in a series of symposia organized by Formal Methods Europe, http://www.fmeurope.org, an independent association whose aim is to stimulate the use of, and research on, formal methods for software development. The symposia have been notably successful in bringing together innovators and practitioners in precise mathematical methods for software development, industrial users as well as researchers. Submissions are welcomed in the form of original papers on research and industrial experience, proposals for workshops and tutorials, entries for the exhibition of software tools and projects, and reports on ongoing doctoral work. FM'06 welcomes all aspects of formal methods research, both theoretical and practical. We are particularly interested in the experience of applying formal methods in practice. The broad topics of interest of this conference are: * Tools for formal methods: tool support and software engineering, environments for formal methods. * Theoretical foundations: specification and modelling, refining, static analysis, model-checking, verification, calculation, reusable domain theories. * Formal methods in practice: experience with introducing formal methods in industry, case studies. * Role of formal methods: formal methods in hardware and system design, method integration, development process. TECHNICAL PAPERS Full papers should be submitted via the web site. Papers will be evaluated by the Program Committee according to their originality, significance, soundness, quality of presentation and relevance with respect to the main issues of the symposium. Accepted papers will be published in the Symposium Proceedings, to appear in Springer's Lecture Notes in Computer Science series, http://www.springeronline.com/lncs . Submitted papers should have not been submitted elsewhere for publication, should be in Springer's format, (see Springer's web site), and should not exceed 16 pages including appendices. A prize for the best technical paper will be awarded at the symposium. INDUSTRIAL USAGE REPORTS One day will be dedicated to sharing the experience -- both positive and negative -- with using formal methods in industrial environments. The Industry Day is organized by ForTIA, the Formal Techniques Industry Association, http://www.fortia.org . This year's Industry Day investigates the use of formal methods in security and trust. Invited papers on organizational and technical issues will be presented. Inquiries should be directed to the Industry Day Chairs; see the web site for details. WORKSHOPS We welcome proposals for one-day or one-and-a-half-day workshops related to FM'06. In particular, but not exclusively, we encourage proposals for workshops on various application domains. Proposals should be directed to the Workshop Chair. TUTORIALS We are soliciting proposals for full-day or half-day tutorials. The tutorial contents can be selected from a wide range of topics that reflect the conference themes and provide clear utility to practitioners. Each proposal will be evaluated on importance, relevance, timeliness, audience appeal and past experience and qualification of the instructors. Proposals should be directed to the Tutorial Chair. POSTER AND TOOL EXHIBITION An exhibition of both research projects and commercial tools will accompany the technical symposium, with the opportunity of holding scheduled presentations of commercial tools. Proposals should be directed to the Poster and Tools Exhibition Chair. DOCTORAL SYMPOSIUM For the first time, FM'06 will feature a doctoral symposium. Students are invited to submit work in progress and to defend it in front of "friendly examiners". Participation for students who are accepted will be subsidized. Submissions should be directed to the Doctoral Symposium Chair. SUBMISSION DATES Technical Papers, Workshops, Tutorials: Friday, February 24, 2006 Posters and Tools, Doctoral Symposium: Friday, May 26, 2006 NOTIFICATION DATES Technical Papers: Friday, April 28, 2006 Workshops, Tutorials: Friday, March 10, 2006 Posters and Tools, Doctoral Symposium: Friday, June 9, 2006 ORGANIZATION General Chair: Emil Sekerinski (McMaster) Program Chairs: Jayadev Misra (U. Texas, Austin), Tobias Nipkow (TU Munich) Workshop Chair: Tom Maibaum (McMaster) Tutorial Chair: Jin Song Dong (NUS) Tools and Poster Exhibition Chair: Marsha Chechik (U. Toronto) Industry Day Chairs: Volkmar Lotz (SAP France), Asuman Suenbuel (SAP US) Doctoral Symposium Chair: Augusto Sampaio (U. Pernambuco) Sponsorship Chair: Juergen Dingel (Queens U.) PROGRAM COMMITTEE Jean-Raymond Abrial (ETH Zurich) Alex Aiken (Stanford U.) Keijiro Araki (Kyushu U.) Ralph Back (Abo Akademi) Gilles Barthe (INRIA) David Basin (ETH Zurich) Ed Brinksma (U. Twente) Michael Butler (U. Southampton) Rance Cleaveland (U. Stony Brook) Jorge Cuellar (Siemens) Werner Damm (U. Oldenburg) Frank de Boer (U. Utrecht) Javier Esparza (U. Stuttgart) Jose Fiadeiro (U. Leicester) Susanne Graf (VERIMAG) Ian Hayes (U. Queensland) Gerard Holzmann (JPL) Cliff Jones (U. Newcastle) Gary T. Leavens (Iowa State U.) Rustan Leino (Microsoft) Xavier Leroy (INRIA) Dominique Mery (LORIA) Carroll Morgan (UNSW) David Naumann (Stevens) E.-R. Olderog (U. Oldenburg) Paritosh Pandya (TIFR) Sriram Rajamani (Microsoft) John Rushby (SRI) Steve Schneider (U. Surrey) Vitaly Shmatikov (U. Texas, Austin) Bernhard Steffen (U. Dortmund) P.S. Thiagarajan (NUS) Axel van Lamsweerde (U. Louvain) Martin Wirsing (LMU Munich) Pierre Wolper (U. Liege) LOCAL ORGANIZATION Publicity: Wolfram Kahl, Alan Wassyng, Jeff Zucker Tools, Posters, Book Exhibition: Spencer Smith Social Events: Ridha Khedri Local Arrangements:: William Farmer, Mark Lawford Events Co-ordinator: Ryszard Janicki ------------------------------------------------------------------------ This e-mail was delivered to you by event@in.tu-clausthal.de, what is a moderated list runned by Computational Intelligence Group of Clausthal University of Technology, Germany. All event announcements sent through this list are also listed in our conference planner at http://cig.in.tu-clausthal.de/index.php?id=planner. In the case of any requests, questions, or comments, do not hesitate and contact event-owner@in.tu-clausthal.de ASAP. ****************************************************** * CIG does not take any responsibility for validity * * of content of messages sent through this list. * ****************************************************** Computational Intelligence Group Department of Computer Science Clausthal University of Technology Germany http://cig.in.tu-clausthal.de/ From rrosebru@mta.ca Wed Oct 26 15:25:26 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Wed, 26 Oct 2005 15:25:26 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EUpor-0006Kx-Ky for categories-list@mta.ca; Wed, 26 Oct 2005 15:16:13 -0300 Date: Tue, 25 Oct 2005 14:19:38 +0200 Message-Id: <200510251219.j9PCJcM01488@www.lmcs-online.org> From: Logical Methods in CS Subject: categories: Journal "Logical Methods in CS" To: Theory interrested people MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: cat-dist@mta.ca Precedence: bulk Status: RO X-Status: X-Keywords: X-UID: 20 ---------------------------------------------------------------------- year 1 of a new journal year 1 of a new journal year one of a new journal -------------------------EXCUSE MULTIPLE COPIES----------------------- Dear Colleague: We are writing to inform you about the progress of the open-access, online journal "Logical Methods in Computer Science," which has recently benefited from a freshly designed web site, see: http://www.lmcs-online.org In the first year of its existence, the journal received 75 submissions: 21 were accepted and 22 declined (the rest are still in the editorial process). The first issue is complete, and we anticipate that will be three in all by the end of the calendar year. Our eventual aim is to publish four issues per year. We also publish Special Issues: to date, three are in progress, devoted to selected papers from LICS 2004, CAV 2005 and LICS 2005. The average turn-around from submission to publication has been 7 months. This comprises a thorough refereeing and revision process: every submission is refereed in the normal way by two or more referees, who apply high standards of quality. We would encourage you to submit your best papers to Logical Methods in Computer Science, and to encourage your colleagues to do so too. There is a flier and a leaflet containing basic information about the new journal on the homepage; we would appreciate your posting and distributing them, or otherwise publicising the journal. We would also appreciate any suggestions you may have on how we may improve the journal. Yours Sincerely, Dana S. Scott (editor-in-chief) Gordon D. Plotkin and Moshe Y. Vardi (managing editors) Jiri Adamek (executive editor) From rrosebru@mta.ca Thu Oct 27 17:30:40 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Thu, 27 Oct 2005 17:30:40 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EVEI7-0001JV-6G for categories-list@mta.ca; Thu, 27 Oct 2005 17:24:03 -0300 Subject: categories: weak double categories? To: categories@mta.ca (categories) Date: Wed, 26 Oct 2005 13:08:41 -0700 (PDT) From: "John Baez" X-Mailer: ELM [version 2.5 PL6] MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: O X-Status: X-Keywords: X-UID: 21 Dear Categorists - If you weaken the notion of 2-category you get the notion of bicategory. Has anyone tried to correspondingly weaken the notion of double category, so that a bicategory is a special sort of "weak double category" in analogy to the ways in which a 2-category is a special sort of double category? Did anyone succeed? Best, jb From rrosebru@mta.ca Thu Oct 27 17:30:40 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Thu, 27 Oct 2005 17:30:40 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EVEJD-0001OI-Am for categories-list@mta.ca; Thu, 27 Oct 2005 17:25:11 -0300 Date: Thu, 27 Oct 2005 14:02:57 +0300 Message-Id: Subject: categories: Coalgebras Conference in Cairo MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable From: "mhebert" To: "categories" Sender: cat-dist@mta.ca Precedence: bulk Status: O X-Status: X-Keywords: X-UID: 22 Dear all, This is to announce the Conference Algebras and Coalgebras, Tools for Geometry, Physics and Computer Science to be held in Cairo, Egypt March 25-30, 2006. Conference page: http://develop.aucegypt.edu/maths/index.html The aim of the conference is to gather mathematicians, mathematical physicists, and computer scientists working in areas closely related to the theory and applications of algebras and coalgebras. Besides exchanging information about the traditional applications of algebras to geometry, physics and computer science in this conference we want to highlight the usefulness of coalgebraic structures in these fields. They appear, for example, in quantum group theory, in symplectic geometry and quantum field theory, in non-commutative geometry, and in computer science. Main Speakers: Prof. Tomasz Brzezinski, University of Wales, Swansea, UK Prof. Heinz-Peter Gumm, University of Marburg, Germany Prof. Pavel Kolesnikov, Sobolev Institute, Novosibirsk, Russia Prof. Juergen Fuchs, Karlstad University, Sweden Prof. Dirk Kreimer, IHES, Paris, France Prof. Shahn Majid, Queen Mary University, London, UK Prof. Robert Wisbauer, University of Duesseldorf, Germany Prof. Farahat Ali, Al-Azhar University, Egypt Organizing Committee: Ismail A. Amin (Cairo) Tomasz Brzezinski (Swansea) Mohamed Fahmy (Cairo) Robert Wisbauer (Duesseldorf) Mohamed Yousif (Cairo and Ohio) Contact: algebra@aucegypt.edu From rrosebru@mta.ca Fri Oct 28 16:28:01 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Fri, 28 Oct 2005 16:28:01 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EVZrc-0001a8-ON for categories-list@mta.ca; Fri, 28 Oct 2005 16:26:08 -0300 References: Content-Type: multipart/alternative; boundary=Apple-Mail-6--279414351 Message-Id: <633CF610-8823-4F2D-BF2F-63911C9E13A9@dima.unige.it> From: Marco Grandis Subject: categories: Re: weak double categories? Date: Fri, 28 Oct 2005 13:32:04 +0200 To: categories@mta.ca Content-Transfer-Encoding: quoted-printable Content-Type: text/plain;charset=ISO-8859-1;delsp=yes;format=flowed Sender: cat-dist@mta.ca Precedence: bulk Status: RO X-Status: X-Keywords: X-UID: 23 Dear John, The definition of weak (or pseudo) double category is what you would =20 expect, once you know the strict case and the definition of =20 bicategory; think of a "pseudocategory object in Cat". It has =20 probably been in the categorical folklore since quite a while. You can find it (including the machinery of lax double functors, =20 horizontal and vertical transformations, etc.) in two papers in =20 Cahiers, where part of the general theory of weak double categories =20 has been developed M. Grandis - R. Pare, Limits in double categories, Cah. Topol. =20 Geom. Diff. Categ. 40 (1999), 162-220, - -, Adjoints for double categories, Cah. Topol. Geom. Diff. =20 Categ. 45 (2004), 193-240. Other papers on (weak) double categories, many of them by Bob Pare et =20= al., are referred to in the articles above. In book form Tom Leinster, Higher operads, higher categories, Cambridge Un. =20 Press 2004, has Section 5.2, devoted to weak double categories. Best regards Marco Marco Grandis Dipartimento di Matematica Universit=E0 di Genova Via Dodecaneso, 35 16146 Genova Italy e-mail: grandis@dima.unige.it tel: +39 010 353 6805 http://www.dima.unige.it/~grandis/ On 26 Oct 2005, at 22:08, John Baez wrote: > Dear Categorists - > > If you weaken the notion of 2-category you get the notion of > bicategory. Has anyone tried to correspondingly weaken the > notion of double category, so that a bicategory is a special > sort of "weak double category" in analogy to the ways in which > a 2-category is a special sort of double category? Did anyone > succeed? > > Best, > jb > > > > > > --Apple-Mail-6--279414351 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=ISO-8859-1
Dear John,

The definition=A0of = weak=A0(or pseudo)=A0double category is what you would expect, once you = know the strict case and the definition of bicategory; think of a = "pseudocategory object in Cat". It has probably been in the categorical = folklore since quite a while.

You can find it=A0(including = the machinery of lax double functors, horizontal and vertical = transformations, etc.)=A0in two papers in Cahiers, where part of the = general theory of weak double categories has been = developed

=A0 =A0M. Grandis - R. Pare, Limits in double = categories, Cah. Topol. Geom. Diff. Categ. 40 (1999), = 162-220,

=A0 =A0- -, = Adjoints for double categories,=A0 Cah. Topol. Geom. Diff. Categ. = 45 (2004), 193-240.

Other papers = on (weak) double categories, many of them by Bob Pare et al., are = referred to in the articles above.
In book = form

=A0 =A0Tom = Leinster, Higher operads, higher categories, Cambridge Un. Press = 2004,

has=A0Section = 5.2, devoted to=A0weak double categories.

Best = regards


Marco = Grandis
Dipartimento di Matematica
Universit=E0 di = Genova
Via Dodecaneso, 35
16146 = Genova
Italy

= tel: +39 010 353 6805

On 26 Oct 2005, at 22:08, John Baez = wrote:

Dear Categorists -

If you = weaken the notion of 2-category you get the notion of
bicategory.=A0 = Has anyone tried to correspondingly weaken the
notion of double category, so that a bicategory is a = special
sort of "weak double category" = in analogy to the ways in which
a 2-category = is a special sort of double category?=A0 Did anyone
succeed?

Best,
jb






= --Apple-Mail-6--279414351-- From rrosebru@mta.ca Fri Oct 28 16:28:02 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Fri, 28 Oct 2005 16:28:02 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EVZok-0001KG-In for categories-list@mta.ca; Fri, 28 Oct 2005 16:23:10 -0300 Subject: categories: Re: weak double categories? From: Tom Leinster To: categories In-Reply-To: References: Content-Type: text/plain Date: Thu, 27 Oct 2005 22:55:51 +0100 Message-Id: <1130450151.13458.19.camel@tl-linux.maths.gla.ac.uk> Mime-Version: 1.0 X-Mailer: Evolution 2.2.1 Content-Transfer-Encoding: 7bit Sender: cat-dist@mta.ca Precedence: bulk Status: RO X-Status: X-Keywords: X-UID: 24 On Wed, 2005-10-26 at 13:08 -0700, John Baez wrote: > If you weaken the notion of 2-category you get the notion of > bicategory. Has anyone tried to correspondingly weaken the > notion of double category, so that a bicategory is a special > sort of "weak double category" in analogy to the ways in which > a 2-category is a special sort of double category? At least three parties have done this: - Bob Pare and collaborators - at least one Australian of the Sean Carmody/Dominic Verity/Steve Lack generation (calling them something like "double bicategories") - me (section 5.2 of book). There's the question of whether you weaken in just one direction or in both. I believe that parties 1 and 3 weaken in just one direction. But you write > in analogy to the ways [*plural!*] in which a 2-category is a special > sort of double category so I guess you're after weakening in both directions. Tom From rrosebru@mta.ca Fri Oct 28 16:28:02 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Fri, 28 Oct 2005 16:28:02 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EVZqc-0001US-1u for categories-list@mta.ca; Fri, 28 Oct 2005 16:25:06 -0300 Date: Fri, 28 Oct 2005 10:10:55 +0100 (BST) From: Richard Garner To: categories Subject: categories: Re: weak double categories? In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; CHARSET=ISO-8859-1; FORMAT=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Content-ID: Sender: cat-dist@mta.ca Precedence: bulk Status: RO X-Status: X-Keywords: X-UID: 25 --On 26 October 2005 13:08 John Baez wrote: > If you weaken the notion of 2-category you get the notion of > bicategory. Has anyone tried to correspondingly weaken the > notion of double category, so that a bicategory is a special > sort of "weak double category" in analogy to the ways in which > a 2-category is a special sort of double category? Did anyone > succeed? Yes, this has been done; I believe Dom Verity=20 is the first person to do this, in his thesis.=20 Grandis and Par=E9 are the only people to have=20 developed extensively aspects of their theory ([1]=20 & [2]). Tom Leinster mentions them in passing (in=20 [3] for example) -- they are the `representable'=20 fc-multicategories, standing in the same relation=20 to them as monoidal categories do to plain=20 multicategories. On my website [4] is my thesis "Polycategories"=20 which contains a fair bit more on weak double=20 categories, both further aspects of their theory=20 and some applications; for those of a terser=20 inclination, the edited highlights can be found in=20 the two preprints "Double clubs" and=20 "Polycategories via pseudo-distributive laws" on=20 the same page. Richard Garner ----- [1] Marco Grandis & Robert Par=E9 Limits in double categories Cah. Topol. G=E9om. Diff=E9r. Cat=E9g. 40 (1999), no. 3, 162--220; MR171677= 9 (2000i:18007) [2] Marco Grandis & Robert Par=E9 Adjoints for double categories Cah. Topol. G=E9om. Diff=E9r. Cat=E9g. 45 (2004), no. 3, 193--240. [3] Tom Leinster Higher operads, higher categories http://arxiv.org/abs/math.CT/0305049 [4] Richard Garner http://www.dpmms.cam.ac.uk/~rhgg2 From rrosebru@mta.ca Fri Oct 28 16:28:02 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Fri, 28 Oct 2005 16:28:02 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EVZsX-0001gg-MV for categories-list@mta.ca; Fri, 28 Oct 2005 16:27:05 -0300 Message-ID: <33740.213.84.47.100.1130515257.squirrel@www.west.nl> Subject: categories: FM'06 Announcement and Call for Submissions To: events@fmeurope.org User-Agent: SquirrelMail/1.4.4 MIME-Version: 1.0 Content-Type: text/plain;charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-Priority: 3 (Normal) Importance: Normal From: events-admin@fmeurope.org Reply-To: events@fmeurope.org List-Archive: Date: Fri, 28 Oct 2005 18:00:57 +0200 (CEST) Sender: cat-dist@mta.ca Precedence: bulk Status: RO X-Status: X-Keywords: X-UID: 26 FM'06: 14TH INTERNATIONAL SYMPOSIUM ON FORMAL METHODS 21 - 27 August 2006 McMaster University, Hamilton, Ontario, Canada http://fm06.mcmaster.ca/ ANNOUNCEMENT AND CALL FOR SUBMISSIONS FM'06 is the fourteenth in a series of symposia organized by Formal Methods Europe, http://www.fmeurope.org, an independent association whose aim is to stimulate the use of, and research on, formal methods for software development. The symposia have been notably successful in bringing together innovators and practitioners in precise mathematical methods for software development, industrial users as well as researchers. Submissions are welcomed in the form of original papers on research and industrial experience, proposals for workshops and tutorials, entries for the exhibition of software tools and projects, and reports on ongoing doctoral work. FM'06 welcomes all aspects of formal methods research, both theoretical and practical. We are particularly interested in the experience of applying formal methods in practice. The broad topics of interest of this conference are: * Tools for formal methods: tool support and software engineering, environments for formal methods. * Theoretical foundations: specification and modelling, refining, static analysis, model-checking, verification, calculation, reusable domain theories. * Formal methods in practice: experience with introducing formal methods in industry, case studies. * Role of formal methods: formal methods in hardware and system design, method integration, development process. TECHNICAL PAPERS Full papers should be submitted via the web site. Papers will be evaluated by the Program Committee according to their originality, significance, soundness, quality of presentation and relevance with respect to the main issues of the symposium. Accepted papers will be published in the Symposium Proceedings, to appear in Springer's Lecture Notes in Computer Science series, http://www.springeronline.com/lncs . Submitted papers should have not been submitted elsewhere for publication, should be in Springer's format, (see Springer's web site), and should not exceed 16 pages including appendices. A prize for the best technical paper will be awarded at the symposium. INDUSTRIAL USAGE REPORTS One day will be dedicated to sharing the experience -- both positive and negative -- with using formal methods in industrial environments. The Industry Day is organized by ForTIA, the Formal Techniques Industry Association, http://www.fortia.org . This year's Industry Day investigates the use of formal methods in security and trust. Invited papers on organizational and technical issues will be presented. Inquiries should be directed to the Industry Day Chairs; see the web site for details. WORKSHOPS We welcome proposals for one-day or one-and-a-half-day workshops related to FM'06. In particular, but not exclusively, we encourage proposals for workshops on various application domains. Proposals should be directed to the Workshop Chair. TUTORIALS We are soliciting proposals for full-day or half-day tutorials. The tutorial contents can be selected from a wide range of topics that reflect the conference themes and provide clear utility to practitioners. Each proposal will be evaluated on importance, relevance, timeliness, audience appeal and past experience and qualification of the instructors. Proposals should be directed to the Tutorial Chair. POSTER AND TOOL EXHIBITION An exhibition of both research projects and commercial tools will accompany the technical symposium, with the opportunity of holding scheduled presentations of commercial tools. Proposals should be directed to the Poster and Tools Exhibition Chair. DOCTORAL SYMPOSIUM For the first time, FM'06 will feature a doctoral symposium. Students are invited to submit work in progress and to defend it in front of "friendly examiners". Participation for students who are accepted will be subsidized. Submissions should be directed to the Doctoral Symposium Chair. SUBMISSION DATES Technical Papers, Workshops, Tutorials: Friday, February 24, 2006 Posters and Tools, Doctoral Symposium: Friday, May 26, 2006 NOTIFICATION DATES Technical Papers: Friday, April 28, 2006 Workshops, Tutorials: Friday, March 10, 2006 Posters and Tools, Doctoral Symposium: Friday, June 9, 2006 ORGANIZATION General Chair: Emil Sekerinski (McMaster) Program Chairs: Jayadev Misra (U. Texas, Austin), Tobias Nipkow (TU Munich) Workshop Chair: Tom Maibaum (McMaster) Tutorial Chair: Jin Song Dong (NUS) Tools and Poster Exhibition Chair: Marsha Chechik (U. Toronto) Industry Day Chairs: Volkmar Lotz (SAP France), Asuman Suenbuel (SAP US) Doctoral Symposium Chair: Augusto Sampaio (U. Pernambuco) Sponsorship Chair: Juergen Dingel (Queens U.) PROGRAM COMMITTEE Jean-Raymond Abrial (ETH Zurich) Alex Aiken (Stanford U.) Keijiro Araki (Kyushu U.) Ralph Back (Abo Akademi) Gilles Barthe (INRIA) David Basin (ETH Zurich) Ed Brinksma (U. Twente) Michael Butler (U. Southampton) Rance Cleaveland (U. Stony Brook) Jorge Cuellar (Siemens) Werner Damm (U. Oldenburg) Frank de Boer (U. Utrecht) Javier Esparza (U. Stuttgart) Jose Fiadeiro (U. Leicester) Susanne Graf (VERIMAG) Ian Hayes (U. Queensland) Gerard Holzmann (JPL) Cliff Jones (U. Newcastle) Gary T. Leavens (Iowa State U.) Rustan Leino (Microsoft) Xavier Leroy (INRIA) Dominique Mery (LORIA) Carroll Morgan (UNSW) David Naumann (Stevens) E.-R. Olderog (U. Oldenburg) Paritosh Pandya (TIFR) Sriram Rajamani (Microsoft) John Rushby (SRI) Steve Schneider (U. Surrey) Vitaly Shmatikov (U. Texas, Austin) Bernhard Steffen (U. Dortmund) P.S. Thiagarajan (NUS) Axel van Lamsweerde (U. Louvain) Martin Wirsing (LMU Munich) Pierre Wolper (U. Liege) LOCAL ORGANIZATION Publicity: Wolfram Kahl, Alan Wassyng, Jeff Zucker Tools, Posters, Book Exhibition: Spencer Smith Social Events: Ridha Khedri Local Arrangements:: William Farmer, Mark Lawford Events Co-ordinator: Ryszard Janicki _______________________________________________ events mailing list events@fmeurope.org http://www.fmeurope.org/mailman/listinfo/events From rrosebru@mta.ca Fri Oct 28 19:38:35 2005 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Fri, 28 Oct 2005 19:38:35 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EVcjt-0003FN-N8 for categories-list@mta.ca; Fri, 28 Oct 2005 19:30:21 -0300 From: Ross Street Subject: categories: Re: weak double categories? Date: Fri, 28 Oct 2005 10:13:24 +1000 To: Categories Content-Transfer-Encoding: 7bit Content-Type: text/plain;charset=US-ASCII Sender: cat-dist@mta.ca Precedence: bulk Message-Id: Status: O X-Status: X-Keywords: X-UID: 27 [Note from moderator: message resent, may have been transmitted incorrectly.] Dominic Verity's PhD thesis did that (amongst other things) for some very good reasons. ---Ross On 27/10/2005, at 6:08 AM, John Baez wrote: > If you weaken the notion of 2-category you get the notion of > bicategory. Has anyone tried to correspondingly weaken the > notion of double category, so that a bicategory is a special > sort of "weak double category" in analogy to the ways in which > a 2-category is a special sort of double category? Did anyone > succeed? From rrosebru@mta.ca Sat Oct 29 09:44:16 2005 -0300 Status: X-Status: X-Keywords: Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Sat, 29 Oct 2005 09:44:16 -0300 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EVpyy-0005ly-SU for categories-list@mta.ca; Sat, 29 Oct 2005 09:38:48 -0300 Message-Id: <200510282107.j9SL7qH13979@math-cl-n03.ucr.edu> Subject: categories: Re: weak double categories? To: categories@mta.ca (categories) Date: Fri, 28 Oct 2005 14:07:52 -0700 (PDT) From: "John Baez" X-Mailer: ELM [version 2.5 PL6] MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: cat-dist@mta.ca Precedence: bulk Dear Categorists - Thanks for all the helpful replies! Tom Leinster wrote: > I guess you're after weakening in both directions. Yes, I need weakening in both directions for my particular application (to quantum gravity, in fact). So, I need to get ahold of Dominic Verity's thesis. Best, jb From rrosebru@mta.ca Sun Oct 30 12:02:53 2005 -0400 Status: X-Status: X-Keywords: Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Sun, 30 Oct 2005 12:02:53 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EWFXg-0005WY-So for categories-list@mta.ca; Sun, 30 Oct 2005 11:56:21 -0400 Date: Sun, 30 Oct 2005 08:59:26 -0500 (EST) From: Peter Freyd Message-Id: <200510301359.j9UDxQFc018751@saul.cis.upenn.edu> To: categories@mta.ca Subject: categories: abelian stuff Sender: cat-dist@mta.ca Precedence: bulk At the recent Ottawa conference I repeated, in passing, something I've been saying for over 30 years: given a subcategory of an abelian category the finite bi-closure is, of course, obtainable by alternately adjoining limits and colimits countably often; remarkably enough, one need only do two cycles (assuming direct sums that's kernels, cokernels, kernels, cokernels). The proof is a consequence of of the construction of free abelian categories. Susan asked me later if I had ever actually worked out a direct proof. Nope. But it became apparent to me, thinking about what I had had to say about free abelian categories that I didn't know 30 years ago, that it shouldn't take two cycles, just one: In the abelian setting, adjoining finite limits commutes with adjoining finite colimits. (No -- for those old enough to remember -- this is not still 1969 and Ottawa is not Seattle.) There are some finicky points one must deal with when talking about images of functors (in the case at hand, functors such as those that assign kernels to maps), so let me just cut here to a critical little lemma that says, in effect, "a kernel of a map between cokernels is a cokernel of a map between kernels:" LEMMA: In an abelian category an exact diagram of the form (all vertical arrows are downwards): c B --> A --> F --> O b | a | | B'--> A'--> F'--> O c' may be enlarged to an exact diagram of the form: O --> K'--> A + B'+ B --> A + A' | | | O --> K ----> A + B'------> A' | c B --> A --> F --> O b | a | | B'--> A'--> F'--> O c' The exactness of K'--> K --> F --> F' says, precisely, that the kernel of F --> F' is the cokernel of K'--> K. The middle vertical K --> F is K --> A + B'--> A --> F where A + B'--> A is the projection map. (For present purposes a projection map is one given by a matrix in which each entry is 1 if such fits else 0.) The two top-right vertical maps are also projection maps. The two top-right horizontal maps are given (as luck would have it) by matrices in which each entry is 1 or a single letter (a,b,c,c') if such fits, else 0. It's not hard to verify this lemma in the category of abelian groups, which -- given the exact representation theorem -- suffices for all abelian categories. As if often the case, the proof of the dual of the lemma harder in the concrete case: CO-LEMMA: In an abelian category an exact diagram of the form (all vertical arrows are downwards): c' O --> K'--> A'--> B' | | a | b O --> K --> A --> B c may be enlarged to an exact diagram of the form: c' O --> K'--> A'--> B' | | a | b O --> K --> A --> B c | A'------> A + B'----> F --> O | | | A'+ A --> A + B'+ B --> F'--> O For the record, note that "a kernel of a map between kernels is a kernel," that is, the same initial exact diagram may be enlarged to a diagram:with exact rows and exact left column: O | O ---> K''--> A'--> A + B; | | | c' O ---> K'---> A'----> B' | | a | b O ---> K ---> A ----> B c The two upper-right verticals are projection maps and the upper right horizontal map is given by a matrix in which each entry is a single letter (a,c'). Also for the record: the finite bi-completion of an additive category is not abelian. Start with the additive closure of a single map f:A --> B. In the finite bi-completion the canonical map from Cok(Ker(f)) to Ker(Cok(f)) will not be an isomorphism. In the finite _abelian_ finite bi-completion, of course, it must be. (It is precisely this isomorphism, invoked at the end of the Lemma in the case f = K --> F, that delivers the commutativity of finite left and right completions.) From rrosebru@mta.ca Sun Oct 30 12:02:53 2005 -0400 Status: X-Status: X-Keywords: Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Sun, 30 Oct 2005 12:02:53 -0400 Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EWFVZ-0005Sa-RY for categories-list@mta.ca; Sun, 30 Oct 2005 11:54:09 -0400 Message-ID: <001f01c5ddba$44768240$ed91fea9@l1> From: "George Janelidze" To: Subject: categories: Generalizing bicategories Date: Mon, 31 Oct 2005 02:27:24 +0100 MIME-Version: 1.0 Content-Type: text/plain;charset="iso-8859-1" Content-Transfer-Encoding: 7bit Sender: cat-dist@mta.ca Precedence: bulk Dear All, In addition to all comments and references given to John Baez, I would like to mention MSc Thesis of my student Nelson Martins-Ferreira, and the paper N. Martins-Ferreira: "Weak categories in additive categories with kernels", Fields Institute Communications, Vol. 43, 2004, 387-410 (and its references). Nelson uses a notion of an internal weak category in a 2-category there (Page 391, Definition 6) and several related/more special notions to develop a convenient setting for 2-dimensional "abelianization". And I would like to use this opportunity to repeat few remarks on the story of abelianization of categorical structures, which I briefly made in my talk on CT1995 in Halifax: (i) It is well known (precise references to be found in various surveys of Ronnie Brown) for a long time that internal 2-categories in an additive category A with kernels can be identified with composable pairs (f,g) of morphisms in A with fg = 0, and that the same is true for n-categories, with n-sequences instead of pairs. Hence, whenever somebody comes up with, say, a new notion of a weak n-category, I would ask: what are the internal weak n-categories in YOUR sense in the category Ab of abelian groups? (Of course this question is "Yoneda invariant", and so there is no difference between considering the category Ab and considering an abstract additive category with kernels here) (ii) Why do we expect a simple answer to the question above? The point is, that most of higher categorical structures involve composition/coherence maps between pullbacks of split epimorphisms - and in the additive case, using kernels of those morphisms, one presents such pullbacks as direct sums and the composition/coherence maps as matrices. Therefore I expect an internal weak n-category in YOUR sense in the category of abelian groups to be nothing but an additive functor from a fixed finitely generated category X to Ab. The only question is: what is X? (iii) There are many examples showing that making comparisons between higher categorical structures might be highly nontrivial; so why not examining first what will happen to them in the simple additive/abelian world? Furthermore, and more generally, if T is a finite limit theory, then the free-forgetful adjunction between Sets and Ab "induces" an adjunction between Models(T) = Models(T,Sets) and Models(T,Ab), and the abelianization (=the left adjoint in that adjunction) Models(T) ---> Models(T,Ab) should help to study the category Models(T). Note that when T is the theory of groups, the abelianization functor becomes the usual one, and so it coincides with the first homology group functor (with coefficients in the additive group of integers). Answering the question from (i), one would certainly begin with bicategories, and, as far as I know, Nelson was the first who has described internal bicategories in additive categories with kernels, and I gave a talk on Nelson's work on Australian Category Seminar in March 2002 - before Nelson himself presented his more general results on the Meeting on Galois Theory, Hopf Algebras, and Semiabelian Categories at Field Institute (Toronto, September 2002). Now results: As shown by Nelson in the abovementioned paper (Section 5.2), an internal weak category in Mor(Ab) (=Cat(Ab)) (which is a special case of Nelson's more general result!) can be identified with a diagram in Ab consisting of morphisms d : A_1 ---> A_0, d' : B_1 ---> B_0, k : A_1 ---> B_1, k' : A_0 ---> B_0, l, r : A_0 ---> A_1, and h : B_0 ---> A_1 with k'd = d'k, kl = kr = 0 and kh = 0. It becomes (a) a bicategory, if B_1 = 0; (b) a double category if l = r = 0 and h = 0; (c) hence, a 2-category if B_1 = 0, l = r = 0 and h = 0. Nelson also examines what would happen without the coherence conditions, and then gets much more complicated formulas (See Proposition 6 in his paper). What Nelson has not done is what Tom Leinster calls "weakening in both directions". Another temptation is the (non-abelian) group case, hence generalizing crossed complexes. Let me also mention S. E. Crans: "Teisi in Ab", Homology, Homotopy and Applications 3, 2001, 87-100, although I do not know if anyone has considered a "double-" version of Crans' teisi. George Janelidze