December 2025 - Categories - categories.org.au

Lecture notes by Bill Lawvere
by Michael Barr, Prof. 23 Apr '26

23 Apr '26

I got a request from someone named C. Muster who is searching for a set of lecture notes by Bill that he gave at U. Laval in 1974. Does anyone have a copy that they would be willing to send to him. Michael You're receiving this message because you're a member of the Categories mailing list group from Macquarie University. To take part in this conversation, reply all to this message. View group files<https://outlook.office365.com/owa/categories@mq.edu.au/groupsubscription.as…> | Leave group<https://outlook.office365.com/owa/categories@mq.edu.au/groupsubscription.as…> | Learn more about Microsoft 365 Groups<https://aka.ms/o365g>

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Subject: Dedicated to R. H. Street’s 80
by George Janelidze 16 Mar '26

16 Mar '26

Dear Colleagues, In honor of the 80th birthday of Professor Ross Howard Street, we are pleased to announce a special issue of Journal of Pure and Applied Algebra dedicated to celebrating his remarkable contributions to category theory and mathematics in general. Topics of interest include (but are not limited to) all areas of pure and applied category theory. The Guest Editors are: Jiří Adámek Maria Manuel Clementino Marino Gran George Janelidze Stephen Lack We are sending this message now so that you can begin to plan for possible submissions. The deadline will be 31 July 2026, and we will write again with further information about submissions once the journal’s website is ready. George Janelidze, on behalf of the Guest Editors Disclaimer - University of Cape Town This email is subject to UCT policies and email disclaimer published on our website at https://www.uct.ac.za/main/email-disclaimer or obtainable from +27 21 650 9111. If this email is not related to the business of UCT, it is sent by the sender in an individual capacity. Please report security incidents or abuse via https://csirt.uct.ac.za/report-incident You're receiving this message because you're a member of the Categories mailing list group from Macquarie University. To take part in this conversation, reply all to this message. View group files<https://outlook.office365.com/owa/categories@mq.edu.au/groupsubscription.as…> | Leave group<https://outlook.office365.com/owa/categories@mq.edu.au/groupsubscription.as…> | Learn more about Microsoft 365 Groups<https://aka.ms/o365g>

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7th Workshop on Formal Topology (7WFTop)-( first annoucement)
by Maria Emilia Maietti 12 Feb '26

12 Feb '26

================================== 7th Workshop on Formal Topology (7WFTop). >From topology to dynamic constructivism, and back. (first announcement) > ------------------------------ The 7th Workshop on Formal Topology will take place in Venice, Italy, on April 13-17, 2026 at Convento di San Francesco della Vigna. This is the seventh of a series of successful meetings on the development of Formal Topology and its connections with related approaches. The first six have been held in Padua (1997), Venice (2002), Padua (2007), Ljubljana (2012), Stockholm (2015), and Birmingham (2019). The meeting is supported by Dipartimento di Matematica “Tullio Levi-Civita” (Università di Padova). ------------------------------ Dynamic constructivism is a new approach to the foundation of mathematics proposed by Giovanni Sambin starting from the 90s and whose forthcoming book is a first organic exposition. The main claim is that mathematics is the result of a dynamic, human process, which stems from the interplay between the construction of mathematical entities, by abstraction and by idealization, and their selection according to their effectiveness in applications to reality and in the organization of mathematics itself. Pointfree topology in the form of Formal Topology and the more recent Positive Topology provides a key tool to link the effective content of mathematics with its ideal one, and thus achieve a synthesis of computation and visual intuition. A careful management of information within a dynamic view "back and forth" from mathematics to its foundation inevitably leads to accepting a plural vision of mathematics, thus enlightening connections between different constructive or even classical approaches to it. INVITED SPEAKERS: Steve Awodey, Andrej Bauer, Ingo Blechschmidt, Francesco Ciraulo, Maria Manuel Clementino, Thierry Coquand, Laura Crosilla, Tom de Jong, Martín Escardó, Hugo Herbelin, Hajime Ishihara, Tatsuji Kawai, Ansten Klev, Takako Nemoto, Michael Rathjen, Giovanni Sambin, Göran Sundholm, Mark van Atten, Steve Vickers, David Wärn, Joshua Wrigley. CONTRIBUTED TALKS There will be room for some contributed talks. Information about abstract submission will appear soon in the website of the workshop. ACCOMODATION The organizers will be happy to help you find accommodation, given the peculiarities of the city of Venice, and are making agreements with some facilities to guarantee partecipants a convenient price for their stay. If you are interested, please write to the workshop email address 7wftop(a)math.unipd.it<mailto:7wftop@math.unipd.it> as soon as possible, indicating "accommodation" in the subject. Finding accommodation at a reasonable price will be difficult or virtually impossible after June-July 2025. REGISTRATION The registration form will be available soon on the workshop website https://events.math.unipd.it/7wftop/. Participation will require a registration fee. SCIENTIFIC COMMITTEE Ingo Blechschmidt (University of Antwerp) Thierry Coquand (Gothenburg University) Martín Escardó (University of Birmingham) Maria Emilia Maietti (University of Padua) Per Martin-Löf (Stockholm University) ORGANIZING COMMITTEE Cipriano Junior Cioffo (University of Pisa) Francesco Ciraulo (University of Padua) Maria Emilia Maietti (University of Padua) Samuele Maschio (University of Padua) Pietro Sabelli (Czech Academy of Science) Giovanni Sambin (University of Padua) CONTACTS For inquiries, please send an e-mail to: 7wftop(a)math.unipd.it<mailto:7wftop@math.unipd.it> You're receiving this message because you're a member of the Categories mailing list group from Macquarie University. To take part in this conversation, reply all to this message. View group files<https://outlook.office365.com/owa/categories@mq.edu.au/groupsubscription.as…> | Leave group<https://outlook.office365.com/owa/categories@mq.edu.au/groupsubscription.as…> | Learn more about Microsoft 365 Groups<https://aka.ms/o365g>

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Algebras of the partial-map classifier monad in 1-toposes
by Martin Escardo 16 Jan '26

16 Jan '26

Dear 1-topos theorists, Anders Kock has a nice paper from the last millennium (1990), about Algebras for the partial map classifier monad https://link.springer.com/chapter/10.1007/BFb0084225 https://tildeweb.au.dk/au76680/jonna5.pdf As he remarks and is well known, and also trivial, in a boolean topos, all algebras are free. Then he goes on to say many interesting things that hold in all 1-toposes. Jon Sterling recently conjectured that, in an arbitrary topos, not all algebras are free. I came up with an example. My question is whether this example is well known, and, moreover, whether more examples are known. First of all, the subobject classifier Ω is a free algebra on one generator. If you think of Ω as the powerset of the terminal object 𝟙, then the structure map of Ω as a free algebra is *union*. (†) But, you can check, also *intersection* exhibits Ω = 𝓟 𝟙 as an algebra. I have proved that this algebra is free if and only if the principle of excluded middle holds, that is, the topos is boolean. Is this known? Then I wanted to find more counter-examples to "every algebra is a free algebra". I tried, first, exponential powers of Ω. But they are free in all toposes. Then I tried, more generally, arbitrary products of free algebras. But, again, they are free in all toposes. Does anybody know a source of more counter-examples? At the moment, the only counter-example I know is (†). It is embarrasing to know only one counter-example. Best wishes, Martin PS. I have written my proofs (on paper and) in a proof assistant, namely Agda (and this is publicly available and advertised in various forums). So this gives some confidence regarding the above claims. I still have to write a human-readable version for public consumption, but here I am more interested in knowning what people already know about this. You're receiving this message because you're a member of the Categories mailing list group from Macquarie University. To take part in this conversation, reply all to this message. View group files<https://outlook.office365.com/groups/groupsubscription?source=EscalatedMess…> | Leave group<https://outlook.office365.com/groups/groupsubscription?source=EscalatedMess…> | Learn more about Microsoft 365 Groups<https://aka.ms/o365g>

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abstract submissions for CT2026; due January 20th, 2026
by Emily Riehl 23 Dec '25

23 Dec '25

The abstract submission portal is now open for contributed talks to CT2026. Participants – both in person and remote – may contribute talks, to be selected by the scientific committee for plenary, parallel, and lightning talk sessions. Abstracts are due on mathprograms.org on January 20th, 2026 by 11:59PM EST. Further instructions, including a LaTeX template for use when preparing abstracts, are available on the conference website: https://ct2026.com/ct/submit/ Questions may be directed to: categorytheory2026(a)gmail.com Attached to this message are posters advertising CT2026 and its satellite conference DV60, in two slightly different aspect ratios (11" x 17" vs A3 standard). -- As a reminder, the 2026 International Category Theory Conference (CT2026) will be held from July 13 – 18, 2026. Invited one-hour lectures will be given by: Geoff Cruttwell, Mount Allison University Tobias Fritz, University of Innsbruck Michael Hoefnagel, Stellenbosch University Ieke Moerdijk, Utrecht University Susan Niefield, Union College Chelsea Walton, Rice University The conference Discoveries and Vistas: Life, the universe, and higher categories (DV60) celebrates the 60th birthday of Dominic Verity, honoring his significant contributions to category theory and homotopy theory. This conference will be held from July 20 – 22, 2026 and will feature one-hour talks from the following invited speakers: John Bourke, Masaryk University Nick Gurski, Case Western Reserve University Mike Hopkins, Harvard University Steve Lack, Macquarie University Félix Loubaton, Max Planck Institute for Mathematics Yuki Maehara, Tokyo Metropolitan University Valeria de Paiva, Topos Institute Martina Rovelli, University of Ottawa Paula Verdugo, Max Planck Institute for Mathematics Dominic Verity, Australian National University We hope many of you will be able to join us in Baltimore or online. CT2026 Organizers Nick Gurski, Case Western Reserve University Philip Hackney, University of Louisiana at Lafayette Angélica Osorno, Reed College Emily Riehl, Johns Hopkins University Maru Sarazola, University of Minnesota CT2026 Scientific Committee Kristine Bauer (Chair), University of Calgary Zurab Janelidze, Stellenbosch University JS Lemay, Macquarie University Ignacio López Franco, Universidad de la República Noah Snyder, Indiana University Todd Trimble, Western Connecticut State University Christina Vasilakopoulou, National Technical University of Athens Noson Yanofsky, Brooklyn College, CUNY DV60 Organizing and Scientific Committee Yuki Maehara, Tokyo Metropolitan University Emily Riehl, Johns Hopkins University Paula Verdugo, Max Planck Institute for Mathematics Jonathan Weinberger, Chapman University You're receiving this message because you're a member of the Categories mailing list group from Macquarie University. To take part in this conversation, reply all to this message. View group files<https://outlook.office365.com/groups/groupsubscription?source=EscalatedMess…> | Leave group<https://outlook.office365.com/groups/groupsubscription?source=EscalatedMess…> | Learn more about Microsoft 365 Groups<https://aka.ms/o365g>

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FLOC 2026 Call for Papers
by Sam Staton 22 Dec '25

22 Dec '25

The Federated Logic Conference (FLoC) unites the ten leading international conferences focused on mathematical logic and its applications in computer science. Since 1996, FLoC is organized every four years and counts with over 2,000 attendees. FLoC 2026 will be held at the Institut Universitaire de Lisbonne (ISCTE) in Lisbon, Portugal, on July 20-23 & July 26-29 (Conferences), July 18-19 & July 24-25 (Workshops), July 13-17 (FoPSS Summer School). FLoC 2026 welcomes original, high-quality contributions on all aspects of logic in computer science. # Important Dates (AoE) CAV - 38th International Conference on Computer Aided Verification https://conferences.i-cav.org/2026/ Paper Submission: January 28, 2026 Author Response Period: March 30 - April 1, 2026 Author Notification: April 17, 2026 Conference Dates: July 26-29, 2026 CP - 32nd International Conference on Principles and Practice of Constraint Programming https://cp2026.a4cp.org Abstract Submission: February 28, 2026 Paper Submission: March 7, 2026 Author Response Period: March 9-12, 2026 Author Notification: April 30, 2026 Conference Dates: July 20-23, 2026 CSF - 39th IEEE Computer Security Foundations Symposium https://csf2026.ieee-security.org Paper Submission: January 29, 2026 Author Notification: April 1, 2026 Conference Dates: July 26-29, 2026 FSCD - 11th International Conference on Formal Structures for Computation and Deduction https://fscd2026.github.io Abstract Submission: January 23, 2026 Paper Submission: January 30, 2026 Author Response Period: March 23–27, 2026 Author Notification: April 16, 2026 Conference Dates: July 20-23, 2026 ICLP - 42nd International Conference on Logic Programming https://www.semsys.aau.at/events/iclp2026/ Abstract Submission (Regular Papers): January 24, 2026 Paper Submission (Regular Papers): January 31, 2026 Author Notification (Regular Papers): March 5, 2026 Paper Submission (Short Papers): March 27, 2026 Revision Submission (Regular Papers): March 27, 2026 Final Author Notification: April 17, 2026 Conference Dates: July 20-23, 2026 IJCAR - 13th International Joint Conference on Automated Reasoning https://www.floc26.org/ijcar Abstract Submission: February 6, 2026 Paper Submission: February 13, 2026 Author Response Period: March 30-31, 2026 Author Notification: April 14, 2026 Conference Dates: July 26-29, 2026 ITP - 17th International Conference on Interactive Theorem Proving https://itp-conference-2026.github.io Abstract Submission: February 12, 2026 Paper Submission: February 19, 2026 Author Notification: April 26, 2026 Conference Dates: July 26-29, 2026 KR - 23rd International Conference on Principles of Knowledge Representation and Reasoning https://kr.org/KR2026/ Abstract Submission: February 8, 2026 (Main Track) Paper Submission: February 13, 2026 (Main Track) Author Response Period: March 24-28, 2026 (Main Track) Author Notification: April 13, 2026 (Main Track) Conference Dates: July 20-23, 2026 LICS - 41st Annual ACM/IEEE Symposium on Logic in Computer Science https://lics.siglog.org/lics26/ Abstract Submission: January 15, 2026 Paper Submission: January 22, 2026 Author Response Period: March 26–29, 2026 Author Notification: April 16, 2026 Conference Dates: July 20-23, 2026 SAT - 29th International Conference on Theory and Applications of Satisfiability Testing https://satisfiability.org/SAT26/ Abstract Submission: February 20, 2026 Paper Submission: February 27, 2026 Author Response Period: April 13-17, 2026 Author Notification: April 30, 2026 Conference Dates: July 20-23, 2026 In addition to the conferences there will be 86 workshops (including Mentoring Workshop, Olympic Games, tutorials, and doctoral consortia)! Learn more and find submission details: https://www.floc26.org/ #FLoC2026 #LogicInCS #Lisbon You're receiving this message because you're a member of the Categories mailing list group from Macquarie University. To take part in this conversation, reply all to this message. View group files<https://outlook.office365.com/groups/groupsubscription?source=EscalatedMess…> | Leave group<https://outlook.office365.com/groups/groupsubscription?source=EscalatedMess…> | Learn more about Microsoft 365 Groups<https://aka.ms/o365g>

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MFPS XLII: First Call for Papers
by Danel Ahman 19 Dec '25

19 Dec '25

# MFPS XLII: Mathematical Foundations of Programming Semantics https://ul-fmf.github.io/mfps-sstt-2026/ ## CALL FOR PAPERS We are delighted to announce the 42nd Conference on the Mathematical Foundations of Programming Semantics (MFPS XLII). It will take place at the Faculty of Mathematics and Physics, University of Ljubljana in Ljubljana, Slovenia, from June 1-3, 2026, where it will be colocated with the 3rd Workshop on Syntax and Semantics of Type Theory (SSTT 2026), which is held from June 4-5, 2026. MFPS conferences are dedicated to the areas of mathematics, logic, and computer science that are related to models of computation in general, and to semantics of programming languages in particular. This is a forum where researchers in mathematics and computer science can meet and exchange ideas. The participation of researchers in neighbouring areas is strongly encouraged. Topics include, but are not limited to, the following: bio-computation; concurrent qualitative and quantitative distributed systems; process calculi; probabilistic systems; constructive mathematics; domain theory and categorical models; formal languages; formal methods; game semantics; lambda calculus; programming language theory; quantum computation; security; topological models; logic; type systems; type theory; denotational and operational semantics; rewrite theory; proof theory. We also welcome contributions that address applications of semantics to novel areas. Participation in the meeting is expected to be in person; one author of every accepted paper has to attend the meeting and give the presentation. Exceptions might be in case there are unexpected problems with travel/visa. Joint website of MFPS XLII and SSTT 2026: https://ul-fmf.github.io/mfps-sstt-2026/ ## INVITED SPEAKERS AND SPECIAL SESSIONS As in previous years, MFPS will have several invited speakers and special sessions highlighting areas within programming languages semantics. We are pleased to announce the following invited speakers and special sessions. ### Invited speakers * Martín Escardó (University of Birmingham) * Cristina Matache (University of Edinburgh) * TBA * TBA ### Special sessions * Proofs and Semantics - in celebration of Alex Simpson’s 60th birthday (organised by Niels Voorneveld) * Quantitative, Graded, and Interactive Semantics (organised by Dominic Orchard) ## SUBMISSION ### Important dates * Paper submission: March 5, 2026 (AoE) * Author notification: April 23, 2026 * Conference: June 1-3, 2026 ### Submissions Submissions are made through EasyChair (https://easychair.org/conferences/?conf=mfps2026) Papers can be at most 15 pages long, excluding bibliography, and should be prepared using the MFPS macros (https://mfpsconf.org/submissions-to-mfps/) Proofs omitted due to space limitations may be included in a clearly marked appendix, to be consulted at the discretion of program committee members. ### Proceedings A preliminary version will be distributed at the meeting. Final proceedings will be published in Electronic Notes in Theoretical Informatics and Computer Science (ENTICS). This new open-access series is hosted by Episciences.org as an overlay for papers published by the CORR arXiv or HAL. ## PROGRAM COMMITTEE * Danel Ahman (University of Tartu) (co-chair) * Pierre Clairambault (CNRS and Aix-Marseille Université) * Nate Foster (Cornell University) * Helle Hvid Hansen (University of Groningen) * Tom de Jong (University of Nottingham) * Robin Kaarsgaard (University of Southern Denmark) * Ohad Kammar (University of Edinburgh) * Anja Petković Komel (Argot Collective) * Ugo Dal Lago (University of Bologna and INRIA Sophia Antipolis) * Paul Blain Levy (University of Birmingham) * Matteo Mio (CNRS/ENS-Lyon) * Max New (University of Michigan) * Valeria de Paiva (Topos Institute) * Paige Randall North (Utrecht University) * Mario Román (University of Oxford) * Jurriaan Rot (Radboud University) (co-chair) * Tarmo Uustalu (Reykjavik University and Tallinn University of Technology) * Jana Wagemaker (Radboud University) * Kazuki Watanabe (National Institute of Informatics) * Thorsten Wißmann (Friedrich-Alexander-Universität Erlangen-Nürnberg) * Noam Zeilberger (Ecole Polytechnique) ## LOCAL ORGANISER * Andrej Bauer (University of Ljubljana) ## CONTACT For any further information about MFPS 2026, please contact the PC co-chairs: Danel Ahman and Jurriaan Rot (mfps2026(a)easychair.org<mailto:mfps2026@easychair.org>) You're receiving this message because you're a member of the Categories mailing list group from Macquarie University. To take part in this conversation, reply all to this message. View group files<https://outlook.office365.com/groups/groupsubscription?source=EscalatedMess…> | Leave group<https://outlook.office365.com/groups/groupsubscription?source=EscalatedMess…> | Learn more about Microsoft 365 Groups<https://aka.ms/o365g>

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Funded PhD Position – University of Birmingham (UK Home Student Only)
by Sergey Goncharov 18 Dec '25

18 Dec '25

Dear all, a fully funded PhD position at the University of Birmingham is available under my supervision, with scholarship for one **UK home student**. The position is in theoretical computer science and will be hosted by the Theory of Computation group at the University of Birmingham. The intended research directions include category theory, type theory, and related areas. Prospective candidates are encouraged to contact me directly, asap and before Christmas. Please include a CV and a brief description of your research interests and motivation. - About me: https://sergey-goncharov.org/ - About Birmingham Theory Group: https://www.birmingham.ac.uk/research/centres-institutes/research-in-comput… Best regards, -- Sergey Goncharov The University of Birmingham https://sergey-goncharov.org School of Computer Science Edgbaston, Birmingham B15 2TT, UK You're receiving this message because you're a member of the Categories mailing list group from Macquarie University. To take part in this conversation, reply all to this message. View group files<https://outlook.office365.com/groups/groupsubscription?source=EscalatedMess…> | Leave group<https://outlook.office365.com/groups/groupsubscription?source=EscalatedMess…> | Learn more about Microsoft 365 Groups<https://aka.ms/o365g>

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Categories of indexed containers
by Neil Ghani 16 Dec '25

16 Dec '25

Aka dependent polynomials. Anyone got a good reference to structure in these categories, eg how much of containers/polynomial functors carries over Cheers Professor Neil Ghani Kodamai Ltd You're receiving this message because you're a member of the Categories mailing list group from Macquarie University. To take part in this conversation, reply all to this message. View group files<https://outlook.office365.com/groups/groupsubscription?source=EscalatedMess…> | Leave group<https://outlook.office365.com/groups/groupsubscription?source=EscalatedMess…> | Learn more about Microsoft 365 Groups<https://aka.ms/o365g>

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Funded PhD positions in Mathematically Structured Programming, Strathclyde (UK), deadline: asap / 22 December 2025
by Vikraman Choudhury 15 Dec '25

15 Dec '25

Dear all, The Mathematically Structured Programming (MSP) Group at the University of Strathclyde is advertising funded PhD positions for UK home students. MSP is a thriving place in the UK to do fundamental research, and students from all backgrounds are welcome! If you are interested in applying, please get in touch with one of us as soon as possible, by 22 December 2025 at the latest. I would be happy to hear from anyone interested in category theory, type theory, and related topics. Official information is available at the following link: https://msp.cis.strath.ac.uk/phd2026-JARSS.html Apologies if you have received multiple postings of this message. -- Vikraman You're receiving this message because you're a member of the Categories mailing list group from Macquarie University. To take part in this conversation, reply all to this message. View group files<https://outlook.office365.com/groups/groupsubscription?source=EscalatedMess…> | Leave group<https://outlook.office365.com/groups/groupsubscription?source=EscalatedMess…> | Learn more about Microsoft 365 Groups<https://aka.ms/o365g>

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