2023 Jun 01st 16:00~17:30 Yan Zhang (张炎, Renmin University of China): Transitive Logics of Finite Depth and Finite Suc-eq-width

In this talk, I will present some results from the study of transitive logics of finite depth and finite suc-eq-width. They are logics in NExtK4 containing the standard depth axioms and the suc-eq-width axioms, which are generalizations of the standard width axioms. The frame condition for a suc-eq-width axiom requires, in a rooted transitive frame, a finite upper bound of cardinality for antichains of points with different sets of proper successors. Our first result demonstrates that all these logics are finitely axiomatizable, thereby generalizing Rybakov and Chagrov’s result….More>>

2023 June 1 14:00-15:30 Penghai Du 杜鹏昊 (Tsinghua University): ​Logic of Link Variations

In this talk, we investigate dynamic modal operators containing cutting, adding and rotating, which have the ability to modify the accessibility relation of a model at both local and global levels. To begin with, we will provide motivation behind this research by exploring the connections between graph games, knowledge graphs, and social networks. We will then introduce the language and semantics used in the logic of global/local link variations, and proceed to show the axiomatization of these logics in its hybrid version, including details about its completeness proof…More>>