Tom de Jong
Postdoc at the University of Nottingham working on type theory. PhD from the University of Birmingham. Mathematician, computer scientist and runner.
Postdoc at the University of Nottingham working on type theory. PhD from the University of Birmingham. Mathematician, computer scientist and runner.
RE: https://types.pl/@typeintype/116420696047590601
The deadline is extended to May 27. Work in progress is very welcome too!
Registration is now open for this year's Scottish Programming Languages and Verification Summer School, held at the University of Glasgow! https://spli.scot/splv/2026-glasgow/
Get your tickets on Eventbrite: https://www.eventbrite.co.uk/e/splv-2026-summer-school-tickets-1989312724911
RE: https://mathstodon.xyz/@de_Jong_Tom/116075617642121293
Application deadline: 1 June. This year's edition will be the 10th!
@chrisTheClimber This really depends on your specific background and how far you'd be travelling and so on. I would say that the important thing is that you're excited. Even if you can't follow all of the talks, I'm sure people would be happy to talk to you, I certainly would!
RE: https://mathstodon.xyz/@de_Jong_Tom/116435680670519184
Just over two weeks before early registration ends (31 May)!
RE: https://mamot.fr/@gallais/116561828663156455
This is coming from SIGCSE: https://sigcsevirtual2026.acm.org/track/sigcse-virtual-2026-papers#Instructions-for-Authors
This is certainly not in the spirit of ACM's policies, nor is it acceptable to scientists.
@Taneb Sorry, what I wrote was confusing. There is no \varepsilon in agda-mode. Only \epsilon (equivalently, \Ge) which displays as ε.
@Taneb @MartinEscardo In fact, I can only get ε (i.e. \varepsilon) even when I type \epsilon.
A month ago I gave a talk on joint work with Christian Sattler, on axioms for higher category theory. The slides are now available here:
https://dwarn.se/slides/7wftop.pdf
The idea is to add axioms to homotopy type theory, to allow a development of higher category theory. Notably, this is consistent with the idea that types are spaces, and does not require any significant changes to the type theory.
Hey!
Want to come visit Aarhus for a week in August and learn about some fun programming languages stuff? Remember to apply for the PLS summer school (deadline June 7). Some financial support for travel is available!
As usual, I was reading this weekend's De Volkskrant (Dutch newspaper) and amused to find @jonmsterling quoted in @ionica's column 🙂
(Minor correction to the column: Jon isn't British.)
3-day workshop on Formal Proof and Synthetic Mathematics to be held in Heidelberg, 24-26 June 2026!
2 mini-courses + 6 research talks
@de_Jong_Tom and @mevenlennonbertrand among the speakers 😊
Registration deadline: May 24th, 2026.
Spread the word! 🫶
#TYPES 2026 is done! The slides for my talk are here: https://tdejong.com/talks/TYPES-2026.pdf.
Joint work with @ljungstrom and @Nicolai_Kraus.
I realise this work is a little marginal in terms of its “significance”, but I really love it and found it so enjoyable.
I was amazed that in order to separate Sierpinski completeness from Segal completeness, we had to use a notion of "proper space” from synthetic topology!
Something new on the arXiv from Jonas Höfer (@jhoefer) and I today: "Univalence without function extensionality" https://arxiv.org/abs/2605.00812
We look at a definition of "equivalence" where instead of asking for homotopies---i.e., pointwise equalities---between the inverses, we ask for equalities of functions. We call this a "categorical equivalence", because its the definition you arrive at if you think of the universe as a wild category. If you define univalence using categorical equivalence, i.e. if you ask for the universe to be a univalent wild category, it turns out you get an axiom that doesn't imply function extensionality! This has long been suspected (https://mathoverflow.net/questions/134449/equivalent-form-of-the-univalence-axiom), but we prove it with a countermodel based on Von Glehn's polynomial construction. This is a construction on models whose outputs always refute function extensionality, but it turns out it carries through some amount of univalence from the base model.
We also show that the canonical map from categorical equivalences to equivalences is a equivalence if and only if function extensionality holds. This is a sharpening of Voevodsky's classic result that univalence implies function extensionality in the universe, and the proof uses the same ideas. To me this is a kind of answer to the old question of what is really going on in Voevodsky's proof, and whether the implication from univalence to funext is really fundamental or just an "accident".
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MFPS XLII (June 1-3) and SSTT 2026 (June 4-5) registration is open!
Registration deadline is
May 25
Registration form and information can be found at
https://ul-fmf.github.io/mfps-sstt-2026/registration/
MFPS XLII and SSTT 2026 at a glance:
Invited speakers:
* Martín Escardó (MFPS)
* Joost-Pieter Katoen (MFPS)
* Cristina Matache (MFPS)
* Ana Sokolova (MFPS)
* Reid Barton (SSTT)
* Ambrus Kaposi (SSTT)
Special sessions:
* Proofs and Semantics - in celebration of Alex Simpson’s 60th birthday (MFPS)
* Quantitative, Graded, and Interactive Semantics (MFPS)
Accepted papers and contributed talks:
* MFPS: https://ul-fmf.github.io/mfps-sstt-2026/mfps-accepted-papers/
* SSTT: https://ul-fmf.github.io/mfps-sstt-2026/sstt-contributed-talks/
please submit to MSFP! (Mathematically Structured Functional Programming), the deadline has been extended to Thursday, May 7th! more info here: https://msfp-workshop.github.io/msfp2026/