Orateur
Anna FELIKSON
(Durham University)
Description
Given a marked surface S, a frieze on S over a ring R is an assignment of elements of R to every arc of S, such that Berenstein - Retakh's exchange relations are satisfied. When R is commutative this simplifies to a usual frieze on a surface i.e. a homomorphism to nonzero elements of R; otherwise we call a frieze noncommutative. A frieze is called unitary when there exists a triangulation in which every arc is assigned with a unit of R. We investigate unitarity of integral friezes over matrices. This is an ongoing work joint with Zack Greenberg and Pavel Tumarkin.