Bass-Serre trees for amalgamated free products of C*-algebras and applications

The Bass—Serre tree associated to an amalgamated free product of groups is a tree on which the group acts in a canonical way. This action is a powerful tool in various studies of the group itself. In this talk, I will introduce its analogy for amalgamated free products of C*-algebras, and explain how ideas coming from geometric group theory can be used in C*-algebra setting.