Seminar Session on June 2

Wednesday 2nd of June at 15:00 hrs we will have another session of our seminar: Katsuhiko Sano (ILLC and Kyoto University) will present his work entitled David Lewis Dynamically Meets Arthur Prior Again with the abstract given below.

The meeting will take place in room B1.25 (beta lounge) in Science Park 904.


In this talk, I will discuss hybrid counterfactual logic from the

static and dynamic perspectives. In the static part, I argue that the
hybrid formalism fits naturally in the context of David Lewis’

counterfactual logic and that the introduction of it into this
framework is desirable. This hybridization enables us to regard the
inference “the pig is Mary; Mary is pregnant; therefore the pig is
pregnant” as a process of revising local information (which depends
on the given situation) by using global information (independent of
the situation). I also explain some technical results of this
combination (e.g. completeness and decidability). In the dynamic part,
I will investigate a possibility of adding some dynamic machinery like
the public announcement operator to hybrid counterfactual logic.
Unlike the ordinary DEL, I will define the updating operation in terms
of Lewis’ sphere models.