5 papers
Minimality for noncommutative dynamical systems
Thomas Bray, Erik Séguin
We consider an alternative notion of minimality for C*-dynamical systems, which we refer to as strong minimality. This notion coincides with the usual definition of minimality in t…
Representation stability for compact and discrete quantum groups
Michael Brannan, Junichiro Matsuda, Erik Séguin
We study approximate representations of locally compact quantum groups and prove stability results in the sense of Ulam in this context. Our main result is that compact and amenabl…
Separation theorems for bounded convex sets of bounded operators
Mikaël Pichot, Erik Séguin
We establish new metric characterizations for the norm (respectively, ultraweak) closure of the convex hull of a bounded set in an arbitrary -algebra (respectively, von Neuman…
Positive definite maps on amenable groups, II
Mikaël Pichot, Erik Séguin
We introduce an Ulam-type stability condition for positive definite maps defined on a countable group and prove that this condition characterizes amenability.
Positive definite maps on amenable groups
Mikaël Pichot, Erik Séguin
We describe conditions that characterize amenability for groups in terms of positive definite functions valued in a von Neumann algebra.