Speaker: David Fernández-Duque (University of Barcelona & Ghent University)
Date and Time: Thursday, November 13th 2025, 16:30-18:00
Venue: online.
Title: Tangled Fragments of the Topological Mu-Calculus.
Abstract. The modal mu-calculus can readily be interpreted over topological spaces using the well known McKinsey-Tarski semantics, an area that has been of interest to various authors for over a decade and has recently found applications in addressing self-referential epistemic puzzles, such as the Surprise Exam paradox. In fact this analysis only uses the perfect core, a very specific mu-definable fixed point. In this talk, we will discuss tangle operators, which despite being mild generalizations of the perfect core can lead to expressively complete fragments yet surprisingly simple fragments of the topological mu-calculus.