Current position

Since 09/2019 :: Post-doc at the department of computer science and engineering of the university of Bologna (research project DIAPASoN – Differential Program Semantics).

Past positions

2018 – 2019 :: Temporary lecturer and research assistant (ATER) at I2M (Institut de Mathématiques de Marseille).


2015 – 2019 :: Ph.D. in mathematics, Aix-Marseille University. Classical realizability: new tools and applications. Advisor: Laurent Regnier. Defended on 29 March 2019.

2011 – 2015 :: École Normale Supérieure diploma, École Normale Supérieure, Paris. Major: mathematics, minor: computer science.

2013 – 2014 :: Research Master (M2): Mathematical Logic and Foundations of Computer Science (LMFI), Paris Diderot University, École Normale Supérieure, Paris. With honours (Mention très bien).

2011 – 2013 :: University degree (L3 and M1) in mathematics, École Normale Supérieure, Paris.

2009 – 2011 :: CPGE (2-year program preparing for entry exams to engineering schools), Lycée Louis le Grand, Paris. Admitted to École Normale Supérieure, group MPI, rank 23rd.

2009 :: High-school diploma (baccalauréat général), scientific option, Lycée Évariste de Parny, Saint Paul (La Réunion, France). With honours (mention très bien, avec les félicitations du jury).


2014 :: Research internship, Universidad de la República, Montevideo (Uruguay). Classical realizability in set theory: an example with the model of threads. Advisor: Alexandre Miquel.


Peer-reviewed publications

2021 :: Laura Fontanella, Guillaume Geoffroy. Preserving cardinals and weak forms of Zorn’s lemma in realizability models. To appear in Mathematical Structures in Computer Science.

01/2021 :: Guillaume Geoffroy, Paolo Pistone. A partial metric semantics of higher-order types and approximate program transformations. CSL 2021: 29th EACSL Annual Conference on Computer Science Logic.

07/2018 :: Guillaume Geoffroy. Classical realizability as a classifier for nondeterminism. LICS 2018: Thirty-First Annual ACM / IEEE Symposium on Logic in Computer Science.

Ph.D. thesis

03/2019 :: Guillaume Geoffroy. Classical realizability: new tools and applications. Ph.D. thesis.

Publications in preparation

Guillaume Geoffroy. Extensional denotational semantics of higher-order probabilistic programs, beyond the discrete case. Under review.

Selected Talks

11/2020 :: Denotational semantics of probabilistic programs, beyond the discrete case, ANR PPS meeting.

09/2018 :: Connecting degrees of parallelism and Boolean algebras through classical realizability, CHoCoLa.

07/2018 :: Classical realizability as a classifier for nondeterminism, LICS 2018.

Scientific meetings

06/2018 :: Realizability in Marseille, co-organiser (with Laura Fontanella).

Science popularisation

:: Co-founder of Pi Day association (

2015 – 2017 :: President of Pi Day association.

14 March 2017 :: Co-author (with Joël Cohen) of the mathematical musical From Marseille to Vegas and co-organiser of the Pi Tour: three performances of the musical in Paris (théâtre des Variétés), Lyon (le Transbordeur) and Marseille (le Silo), accompanied by short scientific talks (attendance: 2000).

14 March 2016 :: Co-author of the mathematical musical Les π travaux d’Archimède and co-organiser of Pi Day in Marseille: one performance of the musical, accompanied by short scientific talks (attendance: 700). The association received the 2016 d’Alembert Award of the French Mathematical Society for this action.


2020 :: Algorithms in Python (30h, lab and TA, bachelor of biology).

2018 – 2019 :: Temporary lecturer and research assistant (ATER) at Aix-Marseille University (192h per year, 2/3 math, 1/3 computer science). Linear algebra; methodology; mathematical language and reasoning (1st year university – L1); C and systems programming (1st year university – L1); research initiation workshops (high school).

2015 – 2018 :: Teaching assistant (chargé de mission d’enseignement) at Aix-Marseille University (64h per year, 2/3 math, 1/3 computer science). Introductory analysis; algebra and geometry (1st year university – L1); C programming (1st and 2nd year university – L1 & L2); logic and computability (graduate course – M2); research initiation workshops (high school).


:: French (native), English, Italian, Spanish.

2017 – 2018 :: Organiser of Café des langues de Luminy, daily multilingual student language exchange group.