Advances in Modal Logic, Volume 13

Logic deals with the fundamental notions of truth and falsity. Modal logic arose from the philosophical study of "modes of truth" with the two most common modes being "necessarily true" and "possibly true". Nowadays modal logic is used to reason about knowledge, about obligations, about programs and about time, among others. Actual research in modal logic spans philosophy, computer science and mathematics using techniques from relational structures, universal algebra, topology, and proof theory. These proceedings record the papers presented at the 2020 conference on Advances in Modal Logic, a biennial conference series with an aim to report on important new developments in pure and applied modal logic. The topics include decidability and complexity results, proof theory, model theory, interpolation, related problems in algebraic logic, as well as history of modal reasoning.