GroLog Seminar
Logic seminar of the University of Groningen
Logic seminar of the University of Groningen
Upcoming GroLog events are listed below. Past events can be found in the Archive page.
SPEAKER: Johannes Kloibhofer
DATE: Thursday 23 April 2026
TIME: 16:00-17:00
PLACE: Bernoulliborg, room 5161.0289
TITLE: Constructing Cyclic Proofs for Interpolation
ABSTRACT:
Craig interpolation has been intensively studied for many logics, and various methods have been proposed to establish this property. In proof theory, Maehara's method is the most common technique for showing interpolation. In recent years, this technique has also been extended to cyclic proof systems, in which the underlying structures of proofs are finite graphs instead of finite trees. In this talk, I will demonstrate how to use cyclic proof systems to prove interpolation, and how to construct suitable cyclic proof systems for which this technique can be employed. Special emphasis will be put on using automata theory to obtain cyclic proof systems with annotations. The logics we consider are modal fixpoint logics, which extend basic modal logic with fixpoint operators. The focus will be on the (two-way) modal μ-calculus and converse propositional dynamic logic.
This talk is based on joint works with Johannes Marti, Francisco Trucco Dalmas and Yde Venema.