*From Lost to the River: Embracing Sort Proliferation*in

*29th International Conference on Types for Proofs and Programs*. Gaëtan Gilbert, Matthieu Sozeau, Pierre-Marie Pédrot & Nicolas Tabareau. , June 2023, pp.14-17.

News

You are on Matthieu Sozeau's website, that's me on the right.
I'm a researcher at Inria in the Gallinette team
in Nantes, and the current coordinator of
the Coq project. Commits are worth a thousand words on my github.

- I'm on 50 percent part time from March 2023 until September 2023.

- July: Giving a lecture on MetaCoq and CertiCoq at the 2023 Summer School on Proof Theory and its Applications
- June: Pierre-Marie Pédrot presented our joint work on sort polymorphism [1] at TYPES 2023 in Valencia.
- April: Together with Yannick Forster, Jakob Botsh Nielsen, Meven Lennon-Bertrand, Nicolas Tabareau and Théo Winterhalter we submitted [2] a journal article on the whole MetaCoq project (version 1.2), now with soundness and completeness of the type-checking and conversion implementations, optimized environment handling and a completely verified erasure pipeline.
- April: MetaCoq version 1.2 [3] has been released.
- January: Coq 8.17+rc1 was released.
- January-March: teaching MPRI 2-7-2, a lecture on proof assistants.

- October: CertiCoq 0.9 beta was released, the first ever verified compiler from Coq to assembly, starting from MetaCoq erased terms and going through CompCert.
- October: Equations 1.3 for Coq 8.17 was released [4], fixing performance issues and bugs.
- October: MetaCoq 1.1.1 was released [5], providing a fully certified checker for Coq and verified erasure.
- September: Yannick Forster presented our joint work on extraction to OCaml from Coq [6]
- June: I co-organized the TYPES 2022 Conference in Nantes with Nicolas Tabareau.
- January-March: teaching MPRI 2-7-2, a lecture on proof assistants.
- January: attended POPL 2022, CoqPL where I gave the traditional Coq Development News [7] and the WITS workshop where I talked about case representation in Coq and MetaCoq [8].
- January: Coq 8.15 was released [9].

- November: Equations 1.3 was released [10].
- October: Coq 8.14 was released [11].
- October: I gave an invited talk at the HoTTest seminar on the MetaCoq Project [12].
- July: I gave an invited talk [13] at the LFMTP'21 workshop affiliated with CADE 28 on the MetaCoq project. The accompanying paper [14] describes the current state of the project.
- July: Together with Kenji Maillard, Nicolas Margulies, Nicolas Tabareau and Eric Tanter, we have submitted a new article on the Multiverse [15], a system to gain logical modularity in proof assistants.
- June: I attended the LICS/ITP 2021 conference and gave a talk [16] on Coq at the Coq Workshop 2021.
- June: I attended the TYPES 2021 conference, and became a new member of the Steering Comittee of TYPES.
- April: I co-organized with Nicolas Tabareau the EPIT 2020 Spring School on Homotopy Type Theory, online.
- March: I was a PC member of the ITP 2021 conference.
- February: Together with Théo Winterhalter, we gave a talk on Coq Coq Correct! [17] online at the Cambium Team seminar, Inria Paris.
- January: Together with Antoine Allioux and Eric Finster, we submitted an article [18] showing that extending univalent/homotopy type theory with polynomial monads suffices to internally build the equivalence between infinity-groupoids and types, check it out! It will be presented at LICS 2021.
- I attended POPL 2021 (online) and gave a talk on Coq Development [19] at CoqPL'21.

- Our article [20] on mixing univalence and parametricity was accepted at the JACM, joint work with Nicolas Tabareau and Éric Tanter.
- Taught Proof Assistants at the MPRI.
- I was part of the POPL'21 program committee.
- I moved to the Gallinette team in Nantes, a team of Inria Bretagne-Atlantique.
- I gave a Tutorial on Equations at CoqPL'20.
- Taught Coq + Equations at the Coq Andes Summer School (CASS) 2020 in Santuario del Río, San José del Maipo, Chile, Jan 6-10 2020.

- Visited Bas Spitters' group in Aarhus and gave a guest lecture on Equations for dependently-typed programming in Coq.
- October: paper "Coq Coq Correct!" [21], on the verification of typechecking and erasure for Coq in Coq was accepted at POPL'20.
- September-December: teaching MPRI 2-7-2 lecture on proof assistatnts.
- September: Yannick Forster presented Coq Coq Codet! [22] at the 10th Coq Workshop colocated with ITP19.
- August: presented Equations Reloaded [23] at ICFP 2019.
- August: talked about Equations for HoTT [24] at the Homotopy Type Theory 2019 conference.
- June-July: Visiting Benjamin Pierce's group at the University of Pennsylvania
- June: Equations Reloaded [25] was accepted for publication at ICFP'19.
- May: Coq 8.10beta1 (with SProp!) and Equations 1.2 were released.
- May: I gave a seminar on MetaCoq and CertiCoq [26] at Nomadic Labs.
- April: submitted an extended version of our ITP'18 paper on The MetaCoq Project [27] to JAR.
- February: I gave an introductory lecture on certified programming and proof assistants [28] for the Master 1 of Computer Science at Paris 7.
- January: I gave a seminar on Definitional Proof-Irrelevance without K [29] at the Deducteam seminar.
- January: Equations 1.2beta was released.
- January: Coq 8.9.0 was released.
- January: Attended POPL'19.

- December: I gave a seminar on programming with Coq [30] attached to Xavier Leroy's lectures on Curry-Howard Today at the Collège de France.
- November: I gave a talk on our universe of strict propositions [31] and Eric Finster gave one on higher universal algebra in type theory at the PPS days.
- October: I gave a talk on the MetaCoq Project [32] at the VALS seminar.
- October: Definitional Proof-Irrelevance without K [33] has been accepted at POPL'19. We present a version of definitionally strict propositions compatible with univalent models. Soon to be found in Coq!
- September-November: MPRI 2.7.2 lecture on proof assistants.
- September: we got the distinguished paper award for our paper "Equivalences for Free!" [34] at ICFP'18.
- September: I am part of the LSFA 2018 program comittee, which will happen in Fortaleza, Brazil in September 2018.
- September: I am part of the TyDe 2018 program comittee colocated with ICFP 2018 in St. Louis, MI.
- August: introductory lecture on Dependent Type Theory at the EUTYPES summer school 2018.
- July: I was part of the ITP 2018 program comittee, and co-organizing the Coq Workshop at FLoC 2018.
- June: I gave an invited talk [35] at the TYPES 2018 conference in Braga, Portugal, June 18-21.
- April: I was an examiner of Amin Timany's PhD, who defended successfully his thesis in KU Leuven, Belgium.
- April 26th: I gave a guest lecture [36] on dependent pattern-matching and Equations at the University of Saarland.
- April 10-11th: participated in the pi.r2 days in Fontainebleau and gave a general talk on Coq as "An Environment for Programming with Dependent Types, take II". Our team is a quite interesting mix!
- April: our paper on Cumulative Inductive Types [37] was accepted at FSCD'18.
- April: our paper on Certified Meta-Programming with Typed Template Coq [38] was accepted at ITP'18.
- March: submitted papers on Equations, an effective ETT to ITT translation [39] and Equivalences for Free! to ICFP.
- January: I attended the EUTypes meeting in Nijmegen where I gave a short talk on handling of recursion in Equations [40].
- January: I attended POPL 2018, PEPM, CPP and CoqPL as well. Giving a presentation + poster at PEPM 2018 on Equations [41], a talk on Typed Template Coq [42] at CoqPL'18, along with the traditional .

- November: participated to the Géocal-LAC days in Nantes, and gave a talk on cumulative inductives types [43].
- October: Coq 8.7 was released, including cumulative inductive types. With Amin Timany, we proved the consistency [44] of this extension using a set-theoretic model.
- October: released Equations version 1.0beta with a handful of examples, and submitted an article on the new version, joint work with Cyprien Mangin.
- October: new article on deriving Equivalences for free with Nicolas Tabareau and Eric Tanter.
- October: with Amin Timany, we proved the soundness of our extension of Coq with Cumulative Inductive Types.
- September: Théo Winterhalter started his PhD in the CoqHoTT team, co-supervised with Nicolas Tabareau.
- June: branching version 8.7 of Coq, which includes cumulative inductive types and integrates the ssreflect plugin.
- June: gave a lecture at EJCP'17 on Type Theory and Interactive Theorem Proving in Coq [45]
- June: at the 3rd Coq's Implementors Workshop in Carnac, Britany.
- May: at TYPES 2017, for our work on cumulative inductive types [46].
- March-April: working on Cumulative Inductive Types with Amin Timany, adding a cumulativity rule to inductives, simulating template polymorphism.
- January-March: MPRI lecture on proof assistants.
- January: Attended CPP 2017, POPL 2017 and CoqPL'17, and had a blast! Greg and Andrew presented our work on CertiCoq [47] there.

- November: we released Coq version 8.6beta1: A Better, Faster, Stronger Rooster!
- November: our paper [48] on the HoTT library got accepted at CPP 2017!.
- November: our presentation on CertiCoq was accepted at CoqPL'17!
- October: the extended version of our paper on was accepted at JFP.
- August: at the ITP 2016 conference and Coq Workshop 2016 in Nancy, where Hugo Herbelin passed me the Coq development coordinator hat [49].
- July: at the Categorical Logic & Univalent Foundations workshop in Leeds, talking about forcing [50]
- July: at ICMS'16, gave a talk on Coq for HoTT [51]
- June: at the DeepSpec kickoff meeting in Princeton, NJ, gave a talk on Coq 8.6 [52] and enjoyed a lot of Coq-related talks!
- May: at the second Coq implementors workshop in Nice, gave a talk on Universes [53] for ML hackers.
- April: our paper [54] on a new call-by-name forcing translation in Type Theory got accepted at LICS.
- March: at the Dagstuhl seminar on "Language Based Verification Tools for Functional Programs", giving a short talk on Equations [55]
- January: Gave a talk [56] at the CoqPL workshop on Coq 8.5
- January: (finally!) released Coq 8.5, including my work on universe polymorphism and primitive projections.

- December-March: Coq lecture at MPRI
- September 1st: Gave a talk [57] on our work on unification with Beta Ziliani at ICFP'15.
- August 1st: at the LFMTP'15 workshop, where Cyprien presented our work on Equations and Predicative System F.
- June 27th-July 3rd: Gave a lecture [58] at the HoTT/UF workshop and attending TLCA'15 in Warsaw.
- June 22-26: first successful Coq coding sprint in lovely Nice, followed by the Coq Workshop
- June 1st: ERC CoqHoTT started!
- May 26th: Gave a lecture [59] on Coq for proving functional programs at the "École de Printemps d'Informatique Théorique" in Fréjus.
- May 8th: Paper on Equations [60] and Predicative System F, joint work with Cyprien Mangin accepted at LFMTP'15.
- May: Paper [61] on a new unification algorithm for Coq, joint work with Beta Ziliani, accepted at ICFP'15. The Coq plugin is here.
- April 29th: Gave a seminar [62] at MIT on our new unification algorithm.
- April 22nd: Released Coq 8.5 beta 2.
- March: Submitted a new version of our work with Nicolas on Internalizing Intensional Type Theory [63].
- January: at POPL'15 in Mumbai, for the first CoqPL workshop, we released Coq 8.5 beta [64].
- December-March 2015: Lecturing on proof assistants at the MPRI.

Copyright © 2006-2015 Matthieu Sozeau