Congratulations to Dmitry Rozplokhas, the VCLA co-chair Agata Ciabattoni, and Matteo Tesi on winning the Best Student Paper Prize for their paper “GL-based calculi for PCL and its deontic cousin” at JELIA 2025! The conference was held in Kutaisi, Georgia, from September 1-4, 2025.

JELIA 2025 is the 19th edition of the European Conference on Logics in Artificial Intelligence. The Best Paper and Best Student Paper Prizes are sponsored by Springer, and each is accompanied by a cash prize amounting to EUR 500. The recipients were selected by the Program Committee, who aimed to determine the contribution of the highest technical excellence and scientific merit. In the case of the Best Student Paper Award, the primary author of the paper had to be a student at the time of submission.

GL-based calculi for PCL and its deontic cousin
Agata Ciabattoni, Dmitry Rozplokhas, and Matteo Tesi

(High level) description of the paper

This paper advances conditional logics, a well-known family of logics central to knowledge representation and reasoning. Conditional logics capture forms of implication that extend beyond classical logic, including:

Prototypical (“Typically, if A, then B”),

Counterfactual (“If A were the case, then B would be”),

Deontic (“B is obligatory under condition A”), and Causal (“A causes B”).

Although the logics formalizing them are closely related, they have often been studied separately. Our work unifies them and develops tools for their application. This research is part of the Logical Methods for Deontic Explanations (LoDEx)
project, funded by the Austrian Science Fund (FWF) under the Weave scheme, in collaboration with partners in Luxembourg (Leon van der Torre) and Germany (Christian Strasser).

Abstract

We introduce a natural sequent calculus for preferential conditional logic PCL via embeddings into provability logic GL, achieving optimal complexity and enabling countermodel extraction. Extending the method to PCL with reflexivity and absoluteness – corresponding to Åqvist’s deontic system F with cautious monotony – we employ hypersequents to capture the S5 modality; the resulting calculus subsumes the known calculi for the weaker systems E and F within Åqvist family.

Read the paper in full here.

ABOUT THE AUTHORS

	Agata Ciabattoni is Professor and Head of the Research Unit Theory and Logic at TU Wien Informatics. She is co-chair of the Vienna Center for Logic and Algorithms (VCLA) and serves as a board member of the cluster of excellence Bilateral AI. She is the principal investigator of the FWF project Logical methods for Deontic Explanations (LoDEx). She is a recipient of the FWF START Prize 2011, the highest Austrian award for early-career researchers.
	Dmitry Rozplokhas is a PhD student in the doctoral program co-funded by the EC “Logics for Computer Science” at TU Wien. He was a recipient of the Ray Reiter Best Paper Prize at the 20th Int. Conf. on Principles of Knowledge Representation and Reasoning KR2023 (with A. Ciabattoni).
	Matteo Tesi is a tenure track researcher (RTT) in logic, philosophy, and history of science at the Scuola Normale Superiore in Pisa. He earned his PhD in 2023 and subsequently held a Marie Skłodowska-Curie Fellowship at the Theory and Logic Group of TU Wien Informatics, supervised by A. Ciabattoni. During this fellowship, he carried out the research that led to this paper.