At PRIMA 2025, the 26th International Conference on Principles and Practice of Multi-Agent Systems held in Modena, Italy, from December 16-19, 2025, LogiCS@TUWien students Josephine Dik, Dominik Pichler and Dmitry Rozplokhas were awarded the Martin Purvis Student Best Paper Award together with their co-authors, VCLA co-chair Agata Ciabattoni and Emiliano Lorini, for their paper “From Explicit Allowances to Defeasible Deontic Operators: A Modal View.” This is the second best paper award for Dmitry (after JELIA 2025), and the fourth best paper award for a paper co-authored by Agata Ciabattoni, in half a year. 

Josephine Dik with the award certificate

Title and abstract of the winning paper:

From Explicit Allowances to Defeasible Deontic Operators: A Modal View
Agata Ciabattoni, Josephine Dik, Emiliano Lorini, Dominik Pichler and Dmitry Rozplokhas

Preference-based deontic logics provide a foundation for normative reasoning but fail to distinguish between explicit allowances – specified by a designer – and implicit ones derived by inference. This distinction is crucial in systems where agents may act only if (explicitly or implicitly) permitted. In this paper, we formalize this inference by grounding the preference ordering over possible worlds in a permission base, i.e., a set of explicit allowances, and derive implicit permissions, as well as defeasible prohibitions and obligations. Our framework provides solutions to key deontic paradoxes and is a conservative extension of Åqvist’s dyadic deontic system F extended with cautious monotony. We illustrate the approach with a case study involving robotic agents operating under normative constraints and provide complexity results together with a QBF-based decision procedure to support automated reasoning.

Read the full paper here.