A generalised tensor product G 0 H of groups G, H has been introduced by R. Brown and J.-L. Loday in [3,4]. It arises in applications in homotopy theory of a generalised Van Kampen theorem. The reason why G 0 H does not necessarily reduce to GUh Oz Huh, the usual tensor product over Z of the abelianisations, is that it is assumed that G acts on H (on the left) and H acts on G (on the left), and...

This paper focuses on the denoising of multidimensional data by a tensor subspace-based method. In a seminal work, multiway Wiener filtering was developed to minimize the mean square error between an expected signal tensor and the estimated tensor. It was then placed in a wavelet framework. The reliable estimation of the subspace rank for each mode and wavelet decomposition level is still pendi...

A detailed study is presented of classical field configurations describing nonabelian vortices in two spatial dimensions, when a global SO(3) symmetry is spontaneously broken to a discrete group IK isomorphic to the group of integers mod 4. The vortices in this model are characterized by the nonabelian fundamental group π1(SO(3)/IK) =Q8, which is isomorphic to the group of quaternions. We prese...