Data:	Mercoledì 7 Febbraio 2007, ore 16.00
Luogo:	Aula 1101, Dip. Matematica, U. Roma "Tor Vergata"
Speaker:	Dr. Ezio Vasselli, Roma
Titolo:	GROUP BUNDLE DUALITY, INVARIANTS FOR C*-ALGEBRAS, AND TWISTED K-THEORY
Abstract:	A duality is discussed for Lie group bundles vs. tensor categories with non-simple identity. Existence and unicity of the dual object (i.e., the group bundle) are not ensured, and we give a complete description of this phenomenon in terms of principal bundles. As an application, we study C*-algebra bundles with fibre a fixed-point algebra of the Cuntz algebra: a classification is given, and a cohomological invariant is assigned, representing the obstruction to perform an embedding into a continuous bundle of Cuntz algebras. Finally, we introduce the notion of twisted gauge-equivariant K-theory.