A note on Lebesgue type decomposition for covariant completely positive maps on -algebras.
An element a of the Banach algebra A is said to be regular provided there is an element b belonging to A such that a = aba. In this note we study the set of regular elements in the Calkin algebra C(X) over an infinite-dimensional complex Banach space X.
The notion of monoidal equivalence for compact quantum groups was recently introduced by Bichon, De Rijdt and Vaes. In this paper we prove that there is a natural bijective correspondence between actions of monoidally equivalent quantum groups on unital -algebras or on von Neumann algebras. This correspondence turns out to be very useful to obtain the behavior of Poisson and Martin boundaries under monoidal equivalence of quantum groups. Finally, we apply these results to identify the Poisson boundary...