2 citations · 2 across the 3 of their papers we have counts for
3 papers
math.OA2005★ 2 cited
On simplicity of reduced C*-algebras of groups
Pierre de la Harpe
A countable group is C*-simple if its reduced C*-algebra is a simple algebra. Since Powers recognised in 1975 that non-abelian free groups are C*-simple, large classes of groups wh…
math.CO2005
Construction of spherical cubature formulas using lattices
Pierre De La Harpe, Claude Pache, Boris B. Venkov
We construct cubature formulas on spheres supported by homothetic images of shells in some Euclidian lattices. Our analysis of these cubature formulas uses results from the theory…
math.CO2005
Expanding graphs, Ramanujan graphs, and 1-factor perturbations
Pierre de la Harpe, Antoine Musitelli
We construct (k+-1)-regular graphs which provide sequences of expanders by adding or substracting appropriate 1-factors from given sequences of k-regular graphs. We compute numeric…