Talk on Tuesday April 14th – Hybrid Epistemic Logics


This Tuesday 14th of April at 15:00 hrs we will have a talk in our seminar’s sessions. This time, Jens Ulrik Hansen will talk about “Hybrid Epistemic Logics” (abstract follows). After the talk, further discussions about the topic and other dynamic business can take place with some drinks!

The meeting will take place in room 3.27 of the P building (Euclides).


When Arthur Prior introduced hybrid logic it was already in the context of temporal logic. Ever since then hybrid logic have found several applications in temporal logics. But hybrid logic is a natural extension of classical modal logic in general. Thus when viewing epistemic logics as modal logics it also make sense to look at hybrid extensions of them. However this has rarely been done, one reason being that interpreting nominals as referring to moments of time comes very natural in a temporal setting, but maybe not as natural in an epistemic setting.

In this talk I will try to present some reasons for investigating hybrid epistemic logics. First of all I will show how hybrid logic sheds light on some of the classical examples of epistemic logic. Then I will show how to add public announcements to hybrid logic and show what useful expressiveness is gained by this. Finally I will present a sound and complete Hilbert style proof system for hybrid public announcement logic and discuss how general completeness results from hybrid logic also extend in the setting of public announcements.