Seminário Análise Funcional e Aplicações 

03/09/2010, 15:00 — 16:00 — Sala P3.10, Pavilhão de Matemática
Steffen Roch, Technische Universität Darmstadt, Germany

Spatial discretization of restricted group C*-algebras

We consider spatial discretizations by the finite section method of the restricted group C*-algebra of a finitely generated discrete group, which is represented as a concrete operator algebra via its left-regular representation. Special emphasis is paid to the quasicommutator ideal of the algebra generated by the finite sections sequences and to the stability of sequences in that algebra. For both problems, the sequence of the discrete boundaries plays an essential role. Finally, for commutative groups and for free non-commutative groups, the algebras of the finite sections sequences are shown to be fractal.