NOL Seminar with Yde Venema
published: 2025-04-11
event date:
2025-04-28
The Nordic Online Logic Seminar
is organised monthly over Zoom, with expository talks on topics of interest for
the broader logic community. The seminar is open for professional or aspiring
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Date Monday, 28 April 2025 at 16:00 CET (UTC+2) on Zoom
Speaker Yde Venema (Professor of Mathematical Logic, University of Amsterdam)
Title Propositional Dynamic Logic (re)visited
Abstract
Propositional dynamic logic (PDL) is a well-known modal logic which originates
from the wave of so-called process logics that emerged in the 1970s.
Characteristic to PDL is that its collection of modalities is given as the set
of regular expressions over some set of atomic programs and (possibly) so-called
test program. The main results on PDL, such as a sound and complete
axiomatisation and the decidability and computational complexity of its
satisfiability problem, were obtained relatively soon after its introducton. In
the talk I will review some results on PDL that have been discovered (or
re-discovered) in more recent years. Topics to be discussed include the relation
of PDL with other fixpoint logics, expressive completeness results and cut-free
proof systems. The main issue that I want to address concerns the Craig
interpolation property for PDL, a long-standing problem that can finally be
settled. I will finish with mentioning some open problems.
The talk is based on work with and by many co-authors.