Data:	Mercoledì 1 Dicembre 2004, Ore 16.00
Luogo:	Aula 1101, Dip. Matematica, U. Roma "Tor Vergata"
Speaker:	Dr. D. Gwion Evans, Dipartimento di Matematica, U. Roma "Tor Vergata"
Titolo:	C*-ALGEBRAS ASSOCIATED WITH DIRECTED GRAPHS AND THEIR HIGHER RANK ANALOGUES
Abstract:	As first observed by Enomoto and Watatani in 1980, it is sometimes more convenient to consider a Cuntz-Krieger algebra OA associated with a finite 0,1-matrix A as the C*-algebra associated with the directed graph EA whose adjacency matrix is A. Indeed they show that certain algebraic properties of OA are closely related with graph theoretic properties of EA. More than a decade later Mann, Raeburn and Sutherland continued this approach in their attempt to understand some C*-algebras arising in the duality theory for compact groups of Doplicher and Roberts. Subsequently, Kumjian, Pask, Raeburn and Renault laid the firm foundations of the current, very satisfying, theory of C*-algebras associated with arbitrary directed graphs (in particular the graphs need not be finite). I shall give a very brief account of the above constructions and, in preparation for Aidan Sims' talk, I shall introduce the intriguing higher rank analogues of directed graphs and their C*-algebras conceived by Kumjian and Pask.