Top-level heading

Higher rho numbers and metrics of positive scalar curvature

Categoria
Seminari di Algebra e Geometria
Data e ora inizio evento
Data e ora fine evento
Aula
Sala di Consiglio
Sede

Dipartimento di Matematica, Sapienza Università di Roma

Speaker

Vito Felice Zenobi (Sapienza Università di Roma)

The analytic surgery sequence is a long exact sequence of K-theory groups which combines topological information (the K-homology of manifolds), index theoretic information (the K-theory of group C*-algebras), and secondary index information (the analytic structure group of Higson-Roe). We will see how to give a definition of terms based entirely on algebras of pseudodifferential operators and their K-theory. We use this to systematically develop maps to an exact sequence of non-commutative de Rham homology/cyclic homology. Via pairings with cyclic cohomology classes, this gives rise to new numeric secondary index invariants (higher rho numbers) with explicit formulas and calculation tools due to the compatibility in the whole sequence. We use this for geometric applications. In particular, we derive new information about the moduli space of Riemannian metrics of positive scalar curvature, where we give new lower bounds on the number of its components.