Prof. **Nick Bezhanishvili** from the University of Amsterdam and Prof. **David Gabelaia** from the Tbilisi State University will give two seminars on **Thursday,** **21 of January 2016 **starting form **16:30** in the **Sala Riunioni** of the** Department of Mathematics.**

**Nick Bezhanishvili:**“

**A gentle introduction to modal spatial logics.”**

**Abstract**: In this talk I will give an overview of modal spatial logics. In particular, I will discuss the MacKinsey and Tarski theorem on the topological completeness of the modal logic S4. I will also review some recent work on topological and geometric modal logics concerning logical analysis of the various notions of dimension.

**David Gabelaia:**“

**Modal logic of 2D polygons**”

**Abstract**: In this talk we investigate the modal logic of the planar polygons. We give axiomatization, prove finite model property and calculate the computational complexity of this logic.