Revisiting Epistemic Logic with Names

Marta Bílková
(Czech Academy of Sciences, Institute of Computer Science)
Zoé Christoff
(University of Groningen)
Olivier Roy
(University of Bayreuth)

This paper revisits the multi-agent epistemic logic presented in [10], where agents and sets of agents are replaced by abstract, intensional "names". We make three contributions. First, we study its model theory, providing adequate notions of bisimulation and frame morphisms, and use them to study the logic's expressive power and definability. Second, we show that the logic has a natural neighborhood semantics, which in turn allows to show that the axiomatization in [10] does not rely on possibly controversial introspective properties of knowledge. Finally, we extend the logic with common and distributed knowledge operators, and provide a sound and complete axiomatization for each of these extensions. These results together put the original epistemic logic with names in a more modern context and opens the door for a logical analysis of epistemic phenomena where group membership is uncertain or variable.

In Joseph Halpern and Andrés Perea: Proceedings Eighteenth Conference on Theoretical Aspects of Rationality and Knowledge (TARK 2021), Beijing, China, June 25-27, 2021, Electronic Proceedings in Theoretical Computer Science 335, pp. 39–54.
Published: 22nd June 2021.

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