The paper investigates an evidence-based semantics for epistemic logics. It is shown that the properties of knowledge obtained from a potentially infinite body of evidence are described by modal logic S5. At the same time, the properties of knowledge obtained from only a finite subset of this body are described by modal logic S4. The main technical result is a sound and complete bi-modal logical system that describes properties of these two modalities and their interplay.
Naumov, P. and J. Tao (2021) "“Attainable Knowledge and Omniscience.” In Joseph Halpern and Andres Perea (eds.), Proceedings of the 18th Conference on Theoretical Aspects of Rationality and Knowledge (TARK 2021) (pp. 251-265). Open Publishing Association.