February 2020 - Categories - categories.org.au

Re: "First" use of 'Category theory' to describe our field
by David Roberts 24 Feb '24

24 Feb '24

Dear Ross, no, that's pretty good! It's mildly surprising that it took ~20 years for the name to 'stick', but maybe less so given that the field grew slowly to start. Thanks, David David Roberts Webpage: https://ncatlab.org/nlab/show/David+Roberts Blog: https://thehighergeometer.wordpress.com On Thu, 11 Jul 2019 at 08:21, Ross Street <ross.street(a)mq.edu.au> wrote: > > Dear David > > From memory, the Pure Mathematics Honours (USyd) course that Max Kelly taught in 1965 > was called ``Category Theory''. It concentrated on different kinds of morphisms > and factorizations in a category, and finished with adjoint functors. > Also John Gray's (UIllinois) 1968-69 graduate course had that name. > > From Eilenberg I heard that each person using categories should have their own category of expertise. > I told this to John Gray who said that was fine; the time had come for that category to be Cat. > > I would suggest that the first category theorists to think of themselves as such were Eilenberg's students at Columbia. > However, Mac Lane was definitely a category theorist. > > This is probably not the verifiable stuff you were seeking. > > Ross > > > On 10 Jul 2019, at 10:01 PM, David Roberts <droberts.65537(a)gmail.com> wrote: > > Hi all, > > the (idle) question is: when did the phrase 'category theory' catch on > for the field? Clearly it didn't leap from either of the heads of > Eilenberg or Mac Lane full-grown, since they used the phrase 'General > theory of natural equivalences'. There are the old 'Reports of the > Midwest Category Seminar' lecture notes (the first in 1967), which > hints that 'category theory' wasn't quite the name in use. > > Even more interesting: who was the first "category theorist", by that name? > > Answers referring to verifiable sources would be best. > > Thoughts? > > David > > > > David Roberts > Webpage: https://ncatlab.org/nlab/show/David+Roberts > Blog: https://thehighergeometer.wordpress.com > [For admin and other information see: http://www.mta.ca/~cat-dist/ ]

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Mario Bunge
by Marco Grandis 01 Mar '20

01 Mar '20

Mario Bunge, the celebrated philosopher and physicist, passed away on February 24th. His Centenary Festschrift was held a few months ago, in September 2019. One can have an idea of his deep, astounding production from this obituary, by Michael Matthews - https://www.hpsst.com/uploads/6/2/9/3/62931075/bunge_obituary.pdf With my wife, we remember with great pleasure his company, his conversation, his friendship, while he stayed in Genoa with Marta in 1993-94, and more recently a few years ago. Our affection and participation to Marta, Eric and Silvia Marco and Maria Teresa Grandis [For admin and other information see: http://www.mta.ca/~cat-dist/ ]

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CMCS 2020: Call for Short Contributions
by Henning Basold 27 Feb '20

27 Feb '20

Call for Short Contributions The 15th International Workshop on Coalgebraic Methods in Computer Science (CMCS'20) Dublin, Ireland, 25 - 26 April 2020 (co-located with ETAPS 2020) www.coalg.org/cmcs20 Objectives and scope -------------------- Established in 1998, the CMCS workshops aim to bring together researchers with a common interest in the theory of coalgebras, their logics, and their applications. As the workshop series strives to maintain breadth in its scope, areas of interest include neighbouring fields as well. Topics of interest include, but are not limited to, the following: - the theory of coalgebras (including set theoretic and categorical approaches); - coalgebras as computational and semantical models (for programming languages, dynamical systems, term rewriting, etc.); - coalgebras in (functional, object-oriented, concurrent, and constraint) programming; - coalgebraic data types, type systems and behavioural typing; - coinductive definition and proof principles for coalgebras (including "up-to" techniques); - coalgebras and algebras; - coalgebras and (modal) logic; - coalgebraic specification and verification; - coalgebra and control theory (notably of discrete event and hybrid systems); - coalgebra in quantum computing; - coalgebra and game theory; - tools exploiting coalgebraic techniques. Venue and event --------------- CMCS'20 will be held in Dublin, Ireland, co-located with ETAPS 2020 on 25 - 26 April 2020. Keynote Speaker --------------- Yde Venema (ILLC, University of Amsterdam, The Netherlands) Invited Speakers ---------------- Nathanaël Fijalkow (CNRS, LaBRI, University of Bordeaux, France) Koko Muroya (RIMS, Kyoto University, Japan) Invited Tutorial Speakers ------------------------- There will be a special session on probabilistic couplings, with invited tutorials by: Marco Gaboardi (University at Buffalo, US) Justin Hsu (University of Wisconsin-Madison, US) Important dates --------------------------- Submission short contributions 4 March 2020 Notification short contributions 11 March 2020 Programme committee ------------------- Henning Basold, Leiden University, The Netherlands Nick Bezhanishvili, University of Amsterdam, The Netherlands Corina Cirstea, University of Southampton, United Kingdom Mai Gehrke, CNRS and Université Côte d'Azur, France Helle Hvid Hansen, Delft University of Technology, The Netherlands Shin-Ya Katsumata, National Institute of Informatics, Japan Bartek Klin, Warsaw University, Poland Ekaterina Komendantskaya, Heriot-Watt University, United Kingdom Barbara König, University of Duisburg-Essen, Germany Dexter Kozen, Cornell University, USA Clemens Kupke, University of Strathclyde, United Kingdom Alexander Kurz, Chapman University, USA Daniela Petrisan, Université Paris 7, France Andrei Popescu, Middlesex University London, United Kingdom Damien Pous, CNRS and ENS Lyon, France Jurriaan Rot, UCL and Radboud University, The Netherlands Davide Sangiorgi, University of Bologna, Italy Ana Sokolova, University of Salzburg, Austria David Sprunger, National Institute of Informatics, Japan Henning Urbat, University of Erlangen-Nuremberg, Germany Fabio Zanasi, University College London, United Kingdom Publicity chair --------------- Henning Basold, Leiden University, The Netherlands PC co-chairs -------------- Daniela Petrisan, Université Paris 7, France Jurriaan Rot, UCL and Radboud University, The Netherlands Steering committee ------------------ Filippo Bonchi, University of Pisa, Italy Marcello Bonsangue, Leiden University, The Netherlands Corina Cirstea, University of Southampton, United Kingdom Ichiro Hasuo, National Institute of Informatics, Japan Bart Jacobs, Radboud University Nijmegen, The Netherlands Bartek Klin, University of Warsaw, Poland Alexander Kurz, Chapman University, USA Marina Lenisa, University of Udine, Italy Stefan Milius (chair), University of Erlangen-Nuremberg, Germany Larry Moss, Indiana University, USA Dirk Pattinson, Australian National University, Australia Lutz Schröder, University of Erlangen-Nuremberg, Germany Alexandra Silva, University College London, United Kingdom Submission guidelines --------------------- Short contributions may describe work in progress, or summarise work submitted to a conference or workshop elsewhere. Accepted short contributions will be bundled in a technical report, and are to be presented at the workshop. They do not appear in the LNCS postproceedings (which only contain regular papers). Short contributions should be submitted electronically as a PDF file via the Easychair system at http://www.easychair.org/conferences/?conf=cmcs2020. [For admin and other information see: http://www.mta.ca/~cat-dist/ ]

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Call for Workshop Proposal - 36th International Conference on Logic Programming (ICLP2020)
by Laura Pandolfo 26 Feb '20

26 Feb '20

*** CALL FOR WORKSHOP PROPOSALS *** ICLP 2020 36th International Conference on Logic Programming September 18 - September 24, 2020 University of Calabria, Rende, Italy https://iclp2020.unical.it ICLP 2020, the 36th International Conference on Logic Programming, will be held at the University of Calabria, Rende, Italy, from September 18 to September 24, 2020. The ICLP conference series has a long standing tradition of hosting a rich set of co-located workshops. ICLP workshops provide a unique opportunity for the presentation and discussion of work that can be preliminary in nature, novel ideas, and new open problems to a wide and interested audience. Co-located workshops also provide an opportunity for presenting specialized topics and opportunities for intensive discussions and project collaboration. The topics of the workshops co-located with ICLP 2020 can cover any areas related to logic programming (e.g., theory, implementation, environments, language issues, alternative paradigms, applications), including cross-disciplinary areas. However, any relevant workshop proposal will be considered. The format of the workshop will be decided by the workshop organizers, but ample time should be allowed for general discussion. Workshops can vary in length, but the optimal duration will be half a day or a full day. Workshop Proposal: ================== Those interested in organizing a workshop at ICLP 2020 are invited to submit a workshop proposal. Proposals should be in English and about two pages in length. They should contain: * The title of the workshop. * A brief technical description of the topics covered by the workshop. * A discussion of the timeliness and relevance of the workshop. * A list of some related workshops held in the last years. * The estimated length of the workshop and an estimate of the number of expected attendees. * The names, affiliation and contact details (email, web page, phone) of the workshop organizers together with a designated contact person. * Previous experience of the workshop organizers in workshop/conference organization. Proposals are expected in text or PDF format. All proposals should be submitted to the Workshop Chair by email by April 13, 2020. Reviewing Process: ================== Each submitted proposal will be reviewed by the Workshop, Program and General Chairs. Proposals that appear well-organized and that fit the goals and scope of ICLP will be selected. The decision will be notified by email to the responsible organizer by April 27, 2020. The definitive length of the workshop will be planned according to the number of submissions received by the different workshops. For every accepted workshop, the ICLP local organizers will prepare a meeting room. The workshops and the conference organizers will collaborate in establishing a uniform approach to produce proficient and accessible proceedings for the workshops. Workshop Organizers' Tasks: =========================== * Producing a "Call for Papers" for the workshop and posting it on the Internet and other means. A web page URL should be provided by May 25, 2020, and will be published on the ICLP 2020 home page. * Providing a brief description of the workshop for the conference program. * Reviewing/accepting submitted papers. * Scheduling workshop activities in collaboration with the local organizers and the Workshop Chair. * Providing a workshop program in a format specified by the conference organizers for posting by August 31, 2020. * Coordinating the preparation of the workshop proceedings according to the specifications provided by the Workshop Chair. Location: ========= Workshops will be collocated with ICLP 2020 at the University of Calabria, Rende, Italy. See the ICLP 2020 web site (https://iclp2020.unical.it/) for location details. Important Dates (Tentative): ============================ April 13, 2020:Proposal submission deadline April 27, 2020:Notification May 25, 2020:Deadline for receipt of CfP and workshop web page URL August 18, 2020: Deadline for acceptance notification of paper authors August 31, 2020: Deadline for workshop program Submissions: ============ Please submit your workshop proposals by email to the Workshop Chair. Workshop Chair: =============== Martin Gebsermartin.gebser(a)aau.at -- -- *Dona il 5x1000* all'Università degli Studi di Sassaricodice fiscale: 00196350904 [For admin and other information see: http://www.mta.ca/~cat-dist/ ]

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SYCO 7 - Call for Participation
by Amar Hadzihasanovic 25 Feb '20

25 Feb '20

======== CALL FOR PARTICIPATION SEVENTH SYMPOSIUM ON COMPOSITIONAL STRUCTURES (SYCO 7) Tallinn University of Technology, Estonia 30-31 March 2020 http://events.cs.bham.ac.uk/syco/7/ ======== The Symposium on Compositional Structures (SYCO) is an interdisciplinary series of meetings aiming to support the growing community of researchers interested in the phenomenon of compositionality, from both applied and abstract perspectives, and in particular where category theory serves as a unifying common language. Previous SYCO events have been held at University of Birmingham, University of Strathclyde, University of Oxford, Chapman University, and University of Leicester. The next SYCO, to be held at Tallinn University of Technology, will host 2 invited talks and 14 contributed talks. Topics range from logical methods in computer science, to higher category theory, through applications of categories in probability and linguistics. INVITED TALKS ======== * Bartek Klin (University of Warsaw) Monadic monadic second order logic * Christine Tasson (IRIF, Universite de Paris) The linear-non-linear substitution 2-monad CONTRIBUTED TALKS ======== * Sivert Aasnaess - Contextuality for circuits * Vikraman Choudhury - Tracking intensional resources using weighted sets and comonads * Elena di Lavore - A proposal for subgame perfection in compositional game theory * Tobias Fritz, Eigil Fjeldgren Rischel - The zero-one laws of Kolmogorov and Hewitt-Savage in categorical probability * Lukas Heidemann - Frames in pretriangulated dg-categories * Nick Hu - External traced monoidal categories * Maxime Lucas - Rewriting strategies as contracting homotopies * Violeta Martins de Freitas - Life in arrows: an introduction to applied category theory * Dylan McDermott, Alan Mycroft - On the relation between call-by-value and call-by-name * Michael Moortgat, Mehrnoosh Sadrzadeh, Gijs Wijnholds - A Frobenius algebraic analysis for parasitic gaps * Olivier Peltre - Homological algebra for message-passing algorithms * Alex Rice - Coinductive invertibility in higher categories * Julian Salamanca Tellez - Distributive laws over the powerset * Niels van der Weide - Constructing finitary 1-truncated higher inductive types as groupoid quotients REGISTRATION ======== Registration is open until Monday 23 March. Details are available on the conference website: http://events.cs.bham.ac.uk/syco/7/ PROGRAMME COMMITTEE ======== Miriam Backens, University of Birmingham Christoph Dorn, University of Oxford Ross Duncan, University of Strathclyde Brendan Fong, MIT Amar Hadzihasanovic, IRIF, Universite de Paris (PC chair) Chris Heunen, University of Edinburgh Alex Kavvos, Aarhus University Marie Kerjean, INRIA Bretagne Atlantique, Equipe Gallinette Kohei Kishida, University of Illinois at Urbana-Champaign Martha Lewis, ILLC, University of Amsterdam Samuel Mimram, Ecole Polytechnique Koko Muroya, RIMS, Kyoto University Jovana Obradovic, Institute of Mathematics CAS Viktoriya Ozornova, Ruhr-Universitaet Bochum Simona Paoli, University of Leicester Mehrnoosh Sadrzadeh, University College London Pawel Sobocinski, Tallinn University of Technology Christina Vasilakopoulou, University of Patras Jamie Vicary, University of Birmingham and University of Oxford Maaike Zwart, University of Oxford [For admin and other information see: http://www.mta.ca/~cat-dist/ ]

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FMCS 2020
by Richard Blute 24 Feb '20

24 Feb '20

28th Foundational Methods in Computer Science Workshop Dept. of Mathematics and Statistics University of Ottawa June 9-12, 2020 Foundational Methods in Computer Science is an annual workshop that brings together researchers in theoretical computer science and category theory. Past workshops have enjoyed talks in areas such as categorical quantum mechanics, restriction categories, database design, and the differential and resource logics. We will host tutorials and talks in several of these and related areas. We especially encourage graduate students to talk. We anticipate having talks and tutorials for the entire day on June 9,10 and 11, with the possibility of additional talks on the morning of the 12th, depending on how many talks are volunteered. This year, FMCS will immediately follow the 2020 Canadian Mathematical Society Summer Meeting, also held in Ottawa. We suggest attendees check out the schedule for that conference as there are a number of sessions of interest to category theorists. Support for graduate students: We particularly encourage graduate students to attend FMCS and to present their work. Some limited funding is available to support graduate students who wish to attend FMCS. To obtain the discounted registration and to apply for this funding you should contact one of the local organizers by April 1st, 2020. Talks: Anyone interested in giving a talk or tutorial should contact the local organizers, no later than May 15th. But earlier is better. Housing: We were unable to reserve housing in the campus dorms, but there will likely be some individual rooms available. Details can be found here: https://www.uottawa.ca/housing/summer-accommodation Some good hotels in the area are: 1-The Business Inn, 180 MacLaren Street. https://thebusinessinn.com/ (This is the best local option.) 2-The Swiss Hotel, 89 Daly Avenue. https://swisshotel.ca/ 3-Alt Hotel, Ottawa, 185 Slater Street. https://www.althotels.com/en/ottawa/ It is recommended not to wait until the last minute to book accommodations. Registration: There will be a small registration fee. It will help to cover refreshments and subsidize students. Local Organizers: Rick Blute (rblute at uottawa dot ca) Pieter Hofstra (phofstra at uottawa dot ca) Phil Scott (philip dot scott at uottawa dot ca) [For admin and other information see: http://www.mta.ca/~cat-dist/ ]

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ICGT 2020: Final Call for Papers (Extended Deadlines)
by Fabio Gadducci 23 Feb '20

23 Feb '20

======================================================= 13th International Conference on Graph Transformation ICGT 2020 http://icgt2020.di.unipi.it <http://icgt2020.di.unipi.it/> co-located with STAF 2020, June 25-26 Bergen, Norway ======================================================= Aims and Scope ------------------------------------------------------- The use of graphs and graph-like structures as a formalism for specification and modelling is widespread in all areas of computer science as well as in many fields of computational research and engineering. Relevant examples include software architectures, pointer structures, state space graphs, control/data flow graphs, UML and other domain-specific models, network layouts, topologies of cyber-physical environments, and molecular structures. Often, these graphs undergo dynamic change, ranging from reconfiguration and evolution to various kinds of behaviour, all of which may be captured by rule-based graph manipulation. Thus, graphs and graph transformation form a fundamental universal modelling paradigm that serves as a means for formal reasoning and analysis, ranging from the verification of certain properties of interest to the discovery of fundamentally new insights. The International Conference on Graph Transformation aims at fostering exchange and collaboration of researchers from different backgrounds working with graphs and graph transformation, either in contributing to their theoretical foundations or by applying established formalisms to classical or novel areas. The conference not only serves as a well-established scientific publication outlet, but also as a platform to boost inter- and intra-disciplinary research and to leeway for new ideas. The 13th International Conference on Graph Transformation (ICGT 2020) will be held in Bergen, Norway, as part of STAF 2020 (Software Technologies: Applications and Foundations). The conference takes place under the auspices of EATCS and IFIP WG 1.3. Proceedings will be published by Springer in the Lecture Notes in Computer Science (LNCS) series. Topics of Interest ------------------------------------------------------- In order to foster a lively exchange of perspectives on the subject of the conference, the programme committee of ICGT 2020 encourages all kinds of contributions related to graphs and graph transformation, either from a theoretical point of view or a practical one. Topics of interest include, but are not limited to the following subjects: - General models of graph transformation (e.g. adhesive categories and hyperedge replacement systems) - Analysis and verification of graph transformation systems - Graph theoretical properties of graph languages - Automata on graphs and parsing of graph languages - Logical aspects of graph transformation - Computational models based on graphs - Structuring and modularization of graph transformation - Hierarchical graphs and decomposition of graphs - Parallel, concurrent, and distributed graph transformation - Term graph and string diagram rewriting - Petri nets and other models of concurrency - Business process models and notations - Bigraphs and bigraphical reactive systems - Graph databases and graph queries - Model-driven development and model transformation - Model checking, program analysis and verification, simulation and animation - Syntax, semantics and implementation of programming languages, including domain-specific and visual languages - Graph transformation languages and tool support - Efficient algorithms (e.g. pattern matching, graph traversal, network analysis) - Applications and case studies in software engineering (e.g. software architectures, refactoring, access control, and service-orientation) - Applications to computing paradigms (e.g. bio-inspired, quantum, ubiquitous, and visual) Important Dates ------------------------------------------------------- Abstract submission: February 28, 2020 (NEW) Paper submission: March 6, 2020 (NEW) Notification: April 10, 2020 Camera-ready: May 01, 2020 Conference: June 25-26, 2020 Submission Guidelines ------------------------------------------------------- Papers can be submitted at http://www.easychair.org/conferences/?conf=icgt2020 <http://www.easychair.org/conferences/?conf=icgt2020> using Springer's LNCS format (http://www.springer.com/lncs <http://www.springer.com/lncs>). For regular and tool demonstration papers, simultaneous submission to other conferences with proceedings or submission of material that has already been published elsewhere is not allowed. The page limits are strict and include references. Papers are solicited in three categories: - Regular papers (limited to 16 pages in Springer LNCS format) describe innovative contributions and are evaluated with respect to their originality, significance, and technical soundness. We also solicit case studies describing applications of graph transformation in any application domain. Additional material intended for reviewers but not for publication in the final version may be included in a clearly marked appendix. - Tool presentation papers (limited to 8 pages in Springer LNCS format) demonstrate the main features and functionality of graph-based tools. A tool presentation paper may have an appendix with a detailed demo description (up to 4 pages), which will be reviewed but not included in the proceedings. - New ideas papers (limited to 2 pages in Springer LNCS format) report on relevant contributions to the theory or applications of graph transformation, which may have been published (or accepted for publication) in a peer-reviewed conference other than ICGT, as a book chapter or journal article since 2018. Papers in this category will be selected for presentation at the conference according to their relevance to the graph transformation community, and they will be considered for the special issues. Submissions will consist of a 2-page abstract. In case of extended abstracts of published papers, the submission must refer to the published paper and include the original paper in PDF. Special Issues ------------------------------------------------------- We are pleased to confirm two special issues for ICGT2020, devoted to the theoretical and application-oriented sides of the conference, respectively. The former is going to appear in Theoretical Computer Science (https://www.journals.elsevier.com/theoretical-computer-science <https://www.journals.elsevier.com/theoretical-computer-science>), the latter has been accepted as special issue in Science of Computer Programming (https://www.journals.elsevier.com/science-of-computer-programming <https://www.journals.elsevier.com/science-of-computer-programming>). Keynote Speaker ------------------------------------------------------- Bob Coecke (University of Oxford, United Kingdom) Program Chairs ------------------------------------------------------- Fabio Gadducci (University of Pisa, Italy) Timo Kehrer (Humboldt-Universität zu Berlin, Germany) Program Committee ------------------------------------------------------- Paolo Baldan, Università degli Studi di Padova, Italy Gábor Bergmann, Budapest University of Technology and Economics, Hungary Paolo Bottoni, Sapienza Università di Roma, Italy Andrea Corradini, University of Pisa, Italy Juergen Dingel, Queen‘s University Kingston, Ontario, Canada Maribel Fernandez, King’s College London, United Kingdom Holger Giese, Hasso-Plattner-Institut Potsdam, Germany Reiko Heckel, University of Leicester, United Kingdom Thomas Hildebrandt, University of Copenhagen, Denmark Wolfram Kahl, McMaster University, Canada Barbara König, Universität Duisburg-Essen, Germany Jean Krivine, IRIF (Institut de recherche en informatique fondamentale, Université de Paris), France Leen Lambers, Hasso-Plattner-Institut Potsdam, Germany Yngve Lamo, Western Norway University of Applied Sciences Bergen, Norway Juan de Lara, Universidad Autónoma de Madrid, Spain Detlef Plump, University of York, United Kingdom Arend Rensink, University of Twente Enschede, Netherlands Leila Ribeiro, Federal University of Rio Grande do Sul (UFRGS) Porto Alegre, Brazil Andy Schürr, Technische Universität Darmstadt, Germany Pawel Maria Sobocinski, Taltech Tallinn University of Technology, Estonia Gabriele Taentzer, Philipps-Universität Marburg, Germany Matthias Tichy, Universität Ulm, Germany Uwe Egbert Wolter, University of Bergen, Norway Steffen Zschaler, King’s College London, United Kingdom Associated Workshops ------------------------------------------------------- We are pleased to announce a series of workshops, held in conjunction with STAF, covering novel aspects of the use of graphs and graph-like structures June 22 — DAMB: Diagrammatic and Algebraic Methods for Business June 23 — STRING: String Diagrams in Computation, Logic and Physics June 24 — GCM: Graph Computation Models (https://sites.google.com/view/gcm2020 <https://sites.google.com/view/gcm2020>) [For admin and other information see: http://www.mta.ca/~cat-dist/ ]

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Re: Interpreting category-valued presheaves
by Ross Street 21 Feb '20

21 Feb '20

Dear Keith Feeling sure that the quasicategory people would have such a result, I asked Alexander Campbell who kindly replied: ``I don't remember a reference for bicategories, but references for quasi-categories are easier to locate: Theorem 5.1.5.6 (on page 345) of Lurie's book 'Higher topos theory' and Theorem 6.3.13 (on page 288) of Cisinski's book 'Higher categories and homotopical algebra' both state that the functor (y_A)^* :Cocts(Psh(A),C) --> Fun(A,C) is an equivalence for any small simplicial set A and cocomplete quasi-category C. '' Now back to me: As far as bicategories are concerned, the fact that the 2-category Hom(C^{op},Cat) of pseudofunctors C^{op}\to Cat is the free cocompletion up to biequivalence of the small bicategory C is a fairly routine generalization of the category case. The basic ingredient is the notion of (bicategorical) colimit colim(J,F) of a pseudofunctor F : C \to K weighted by a pseudofunctor J : C^{op}\to Cat; see [14. Fibrations in bicategories, Cahiers de topologie et g\'eom\'etrie diff\'erentielle 21 (1980) 111--160] The extension of F to a weighted colimit preserving pseudofunctor is colim(-,F) : Hom(C^{op},Cat) \to K when K has small weighted colimits. Also of interest, a few years ago Ren\'e Guitart pointed out a lax cocompletion property of a familiar construction (not quite presheaves or prestacks) in his talk ``Sur le foncteur diagramme'' <http://archive.numdam.org/article/CTGDC_1973__14_2_153_0.pdf>. Ross On 20 Feb 2020, at 7:16 AM, Keith Harbaugh <keith.harbaugh(a)gmail.com<mailto:keith.harbaugh@gmail.com>> wrote: Dear Ross, can you recommend a good source for the extension of this result to the setting of weaker notions of categories and functors? On Wed, Feb 19, 2020, 13:35 Ross Street <ross.street(a)mq.edu.au<mailto:ross.street@mq.edu.au>> wrote: Dear Redi Haderi Max Kelly's book ``Basic concepts of enriched category theory'' generalises this whole Kan business to V-categories for a decent base V. So, for the case V = Cat, you obtain the result for 2-categories. I say ``the result'', but of course, for 2-categories there are versions for weaker structures (bicategories, pseudofunctors, and so on). The Cat-enriched version is the strict case which you seem to want. [For admin and other information see: http://www.mta.ca/~cat-dist/ ]

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YaMKittens: Introductory categories day 28 March, Birmingham. Please spread the word!
by Steve Vickers 20 Feb '20

20 Feb '20

This message is to ask your help in publicising a 1-day introductory categories meeting for undergraduate and masters students. You may know already about YaMCATS, the Yorkshire and Midlands Category Theory Seminar https://www2.le.ac.uk/departments/mathematics/extranet/staff-material/staff… This year’s Birmingham meeting on Saturday 28 March will be a junior “YaMKittens” version, aimed especially at undergraduates and masters students to give them a taster in category theory. Tom Leinster and Bob Coecke have agreed to be our two speakers, presenting an hour and a half each, and covering basic principles and abstractions as well as a good case study. We aim to cover students’ travel costs. If you know of any populations of students who might be interested, and live close enough to Birmingham, please encourage them to register (no fee) and come to the meeting. Further details are at https://www.cs.bham.ac.uk/~sjv/YaMKittens/ All the best, Steve Vickers [For admin and other information see: http://www.mta.ca/~cat-dist/ ]

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Interpreting category-valued presheaves
by Redi Haderi 19 Feb '20

19 Feb '20

Dear categorists, I could not find an answer to the following, so I need your help: Given a category C we know that the category of set-valued presheaves on C may be interpreted as a free cocompletion of C. More precisely, if we denote PSh(C) the presheaf category, then colimit-preserving functors from PSh(C) to a cocomplete category D correspond to functors from C to D (via Yoneda extension). I am interested in an interpretation of category-valued presheaves. Is there some sort of 2-categorical version of the above fact? Best regards, Redi Haderi [For admin and other information see: http://www.mta.ca/~cat-dist/ ]

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