Neural multigrid for gauge theories and other disordered systems

We present evidence that multigrid works for wave equations in disordered systems, e.g. in the presence of gauge fields, no matter how strong the disorder, but one needs to introduce a "neural computations" point of view into large scale simulations: First, the system must learn how to do the simulations efficiently, then do the simulation (fast). The method can also be used to provide smooth interpolation kernels which are needed in multigrid Monte Carlo updates.Comment: 9 pages [2 figures appended in PostScript format], preprint DESY 92-126, Sept. 199

Degenerate series representations of the universal covering group of SU(2, 2)

AbstractWe prove a reducibility criterion for certain families of representations induced from irreducible finite dimensional representations of the 11-dimensional parabolic subgroup of the universal covering group of SU(2, 2). If an induced representation is reducible and can be considered as a representation of SU(2, 2) as well, we compute the number of composition factors

Some branching laws for symmetric spaces

In this paper we consider the unitary symmetric spaces of the form X=U(p,q)/U(1)U(p,q-1) and their discrete series representations. Inspired by the work of A.Venkatesh and Y.Sekellarides on L-groups of p-adic spherical spaces we formulate and prove natural relative branching laws for the restriction to smaller subgroups of the same type and corresponding unitary spaces.We think of this as steps to formulation and proving Gan Gross Prasad conjectures for unitary spaces. Using period integral and some results of T.Kobayashi we prove an analogue of thesis conjectures