Dr E Goubault (ENS, Paris; Commission Energie Atomique) will visit the School of Informatics, University of Wales, Bangor, UK, on Dec 19, 20 2000 and give two talks, the second of which will be more mathematical: Tuesday, Dec 19, 4:00pm, Room 149 Geometric semantics for the analysis of concurrent and distributed software ABSTRACT: This talk will be focused on applications of geometrical ideas and modeling to computer scientific problems, among which: - relationship with other models for concurrency (for instance transition systems and Petri nets). - static analysis of concurrent programs (mostly Java-like threads); in particular, deadlocks, reachable states, scheduling properties (joint work with Martin Raussen and Lisbeth Fajstrup), state-space reduction techniques. - scheduling properties of distributed systems; in particular serialisability conditions for databases (after Jeremy Gunawardena and Martin Raussen), computability in fault-tolerant systems (after Maurice Herlihy and Sergio Rajsbaum). Wednesday, Dec 20th 11:15 pm, Room S5 Recent developments of "geometric concurrency theory" ABSTRACT: In this talk, I will present some of the "geometrical theories" used for modeling concurrent systems. Among these are: - the (di-)topological approaches where the flow of concurrent executions is modeled by a topological space of states plus local partial orders on it. This is very much related to the "progress graphs" of E. W. Dijkstra. I will also outline some links with similar objects introduced in domain theory. Some of the algebraic topology which is useful for describing interesting (scheduling) properties of concurrent systems will be described (many results from Martin Raussen and Lisbeth Fajstrup, Aalborg University). I will also refer to recent work by Stefan Sokolowski, Gdansk University. - the semi-cubical set approach which is in some way a combinatorial counterpart of the topological approach. This is very much related to ordinary transition systems semantics. This was described first by Vaughan Pratt and Rob van Glabbeek, Stanford University. - the omega-categorical approach (cubical and/or globular of course) initiated also by Vaughan Pratt. Most of this work has been developped by Philippe Gaucher, IRMA, Strasbourg University. I will add some recent developments (joint work with Philippe Gaucher), and also some other "applications" of these ideas (in Logics, joint work with Jean Goubault-Larrecq). All are welcome. It is hoped the above schedule will allow good time for discussion. Enquiries to Ronnie Brown r.brown@bangor.ac.uk