TITLE: On modal fixpoint logics: where logic meets automata and games SPEAKER: Prof. Alessandro Facchini (Informatic Institute, Warsaw, Polland) WHEN: Friday, July 4th, 11:00 am WHERE: IDSIA Meeting room - Galleria 1, Manno ABSTRACT: Modal fixpoint logics constitute a very lively and interesting research field. The reasons of this success are twofold. On the one hand computer scientists extensively use these formalisms to capture the relevant formal aspects of the system they want to build, as it is the case with LTL, CTL and PDL in software verification, or with conditional and regular XPath in database theory. On the other hand, the mathematical theory of modal fixpoint logics has unveiled deep and rich connections with fields as diverse as automata theory, topology and game theory. But despite this success story, the actual situation is paradoxical: modal fixpoints are used everywhere in computer science, but the working computer scientist is still lacking a clear mathematical understanding of them. In this talk I present the content of my present research program, whose goal is to make a step towards the understanding of the mathematical landscape behind modal fixpoints by studying expressiveness and structural problems of this formalisms, in particular of the modal mu-calculus. Some of the first obtained results have been published at LICS 2013, CSL-LICS 2014 and CiE 2014. Short bio: Alessandro Facchini is assistant professor at the Informatics Institute of the University of Warsaw, where is leading a Homing Plus project on the expressiveness of fixpoint logics, co-financed by the FNP and the European Union. After studying logic, linguistics and mathematics at the Universities of Neuchâtel and Barcelona, he obtained a PhD in Computer Science, joint from the Universities of Bordeaux 1 (LaBRI) and Lausanne. For the results obtained during his doctoral studies, he was awarded of the Paul Bernays Award 2011. He has been research associate at the Informatics Institute of the University of Amsterdam (EU FP7 project), and visiting researcher at the Jack Baskin School of Engineering, University of California Santa Cruz, at the ILLC, University of Amsterdam, and at the Laboratory for Foundations of Computer Science, University of Edinburgh. He is also research associate at the UMR7597, CNRS-University Paris 7.