2026 E. W. Beth Dissertation Prize

The 2026 prize went jointly to Adrienne Lancelot (PhD Paris 2025) and Keya Prakash (PhD Warwick 2025).

Adrienne Lancelot’s thesis Comparing Functional Programs, Or How to Put Lambda-terms Back in Order (Institut Polytechnique de Paris) makes fundamental contributions to the theory of program equivalence in the lambda calculus, addressing the challenge of reconciling semantic correctness with concerns of efficiency and cost. Through new results on contextual equivalence and call-by-value semantics, it advances our understanding of functional programming languages. Reviewers praised the thesis for its originality, mathematical rigor, and clarity, highlighting it as a landmark contribution to the field.

Keya Prakash’s thesis History-Deterministic Parity Automata: Games, Complexity, and the 2-Token Theorem (University of Warwick) makes major contributions to the theory of history-deterministic parity automata, resolving a central open problem concerning their characterization and its complexity. By proving the 2-token conjecture and developing new techniques for history-deterministic automata, it significantly advances the understanding of nondeterminism in automata theory. Reviewers praised the thesis for its innovative methods, exceptional clarity, and solution of a longstanding open problem, describing it as an outstanding contribution that will shape future research in the field.

Call for Nominations for the 2026 Beth Prize (closed)

Since 1998, the Association for Logic, Language, and Information (FoLLI) has been awarding the annual E.W. Beth Dissertation Prize to outstanding Ph.D. dissertations in Logic, Language, and Information, with financial support of the E.W. Beth Foundation.

Information about the qualifications for the 2026 E.W. Beth Dissertation Prize:

• Ph.D. dissertations concerning a topic in Logic, Language, or Information are eligible for the prize, if the degree was awarded between January 1st and December 31st, 2025.
• There are no restrictions on the nationality, ethnicity, age, gender or employment status of the author of the nominated dissertation, nor on the university, academic department or scientific institution formally conferring the Ph.D. degree, nor on the language in which the dissertation has originally been written.
• In accordance with the aim of the Beth Foundation to continue and extend the work of the Dutch logician Evert Willem Beth, nominations are invited of excellent dissertations on topics in the broad remit of ESSLLI, including current topics in philosophical and mathematical logic, computer science logic, philosophy of science, philosophy of language, history of logic, history of the philosophy of science and scientific philosophy in general, as well as the current theoretical and foundational developments in information and computation, language, and cognition. Dissertations with results more broadly impacting various research areas in their interdisciplinary investigations are especially solicited.
• If the committee decides that a nominated dissertation in a language other than English requires translation to English for proper evaluation, the committee can transfer its nomination to the competition in 2027. The English translation must in such cases be submitted before the deadline of the call for nominations in 2027. The committee may recommend the Beth Foundation to consider supporting such nominated dissertations for English translation, upon request by the author of the dissertation.

The prize consists of:

• a certificate
• a donation of 3000 euros, provided by the E.W. Beth Foundation. In case two dissertations are selected, the prize will be split between the winners.
• an invitation to submit the dissertation, possibly after revision, for publication in FoLLI Publications on Logic, Language and Information (Springer)

General submission guidelines:

• Only digital submissions are accepted, without exception. Hard copy submissions are not allowed. The following documents are to be submitted in the nomination dossier:
• The original dissertation in pdf format (ps/doc/rtf etc. not acceptable).
• A 10-page English abstract of the dissertation (including references), presenting the main results of each chapter.
• A letter of nomination from the dissertation supervisor, which concisely describes the scope and significance of the dissertation, stating when the degree was officially awarded and the members of the Ph.D. committee. Nominations should contain the address, phone and email details of the nominator.
• Two additional letters of support, including at least one from a referee not affiliated with the academic institution that awarded the Ph.D. degree, nor otherwise related to the nominee (e.g. former teachers, supervisors, co-authors, publishers or relatives) or the dissertation. Thesis committee members (not from the awarding institution) are eligible as referees.
• Self-nominations are not possible.
• FoLLI is committed to diversity and inclusion and we welcome dissertations from all under-represented groups.

All pdf documents must be submitted electronically, as one pdf file, via EasyChair by following the link https://easychair.org/my2/conference?conf=beth26

The deadline has been extended to April 20th, 2026, AoE.

In case of any problems or questions please contact the chair of the committee Yoad Winter (y.winter(at)uu.nl).

The prize will be awarded by the chair of the committee and members of the FoLLI board at a ceremony during the 37th ESSLLI summer school in Prague, 3–14 August 2026.