Jérémy Ledent

Selected papers

1. Epistemic Logic

   A Many-Sorted Epistemic Logic for Chromatic Hypergraphs

   Éric Goubault, Roman Kniazev, and Jérémy Ledent

   In 32nd EACSL Annual Conference on Computer Science Logic (CSL 2024)

   Abstract Bibtex URL arXiv PDF

   We propose a many-sorted modal logic for reasoning about knowledge in multi-agent systems. Our logic introduces a clear distinction between participating agents and the environment. This allows to express local properties of agents and global properties of worlds in a uniform way, as well as to talk about the presence or absence of agents in a world. The logic subsumes previous attempts at epistemic logic with variable number of agents. The semantics is given in chromatic hypergraphs, a generalization of chromatic simplicial complexes, which were recently used to model knowledge in distributed systems. We show that the logic is sound and complete with respect to the intended semantics. We also show a further connection of chromatic hypergraphs with neighborhood frames.

   @InProceedings{goubault2023manysorted,
     author =	{Goubault, \'{E}ric and Kniazev, Roman and Ledent, J\'{e}r\'{e}my},
     title =	{{A Many-Sorted Epistemic Logic for Chromatic Hypergraphs}},
     booktitle =	{32nd EACSL Annual Conference on Computer Science Logic (CSL 2024)},
     pages =	{30:1–30:18},
     series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
     ISBN =	{978-3-95977-310-2},
     ISSN =	{1868-8969},
     year =	{2024},
     volume =	{288},
     editor =	{Murano, Aniello and Silva, Alexandra},
     publisher =	{Schloss Dagstuhl – Leibniz-Zentrum f{\ü}r Informatik},
     address =	{Dagstuhl, Germany},
     doi =		{10.4230/LIPIcs.CSL.2024.30},
   }

2. Epistemic Logic,
   Topology

   Semi-Simplicial Set Models for Distributed Knowledge

   Éric Goubault, Roman Kniazev, Jérémy Ledent, and Sergio Rajsbaum

   In 38th Annual ACM/IEEE Symposium on Logic in Computer Science (LICS 2023)

   Abstract Bibtex URL arXiv Slides More slides

   In recent years, a new class of models for multi-agent epistemic logic has emerged, based on simplicial complexes. Since then, many variants of these simplicial models have been investigated, giving rise to different logics and axiomatizations. In this paper, we present a further generalization, which encompasses all previously studied variants of simplicial models. Geometrically, this is achieved by generalizing beyond simplicial complexes, and considering instead semi-simplicial sets. By doing so, we define a new semantics for epistemic logic with distributed knowledge, where a group of agents may distinguish two worlds, even though each individual agent in the group is unable to distinguish them. As it turns out, these models are the geometric counterpart of a generalization of Kripke models, called “pseudo-models”. We show how to recover the previously defined variants of simplicial models as sub-classes of our models; and give a sound and complete axiomatization for each of them.

   @inproceedings{GoubaultKLR23semisimplicial,
     author       = {{\'{E}}ric Goubault and
                     Roman Kniazev and
                     J{\'{e}}r{\'{e}}my Ledent and
                     Sergio Rajsbaum},
     title        = {Semi-Simplicial Set Models for Distributed Knowledge},
     booktitle    = {38th Annual ACM/IEEE Symposium on Logic in Computer Science (LICS)},
     pages        = {1–13},
     year         = {2023},
     url          = {https://doi.org/10.1109/LICS56636.2023.10175737},
     doi          = {10.1109/LICS56636.2023.10175737},
   }