2 8 N ov 2 00 3 The Radicals of Crossed Products ∗

N ov 2 00 3 HOMOLOGICAL DIMENSION OF CROSSED PRODUCTS ∗

Throughout this paper, k is a field, R is an algebra over k, and H is a Hopf algebra over k. We say that R# σ H is the crossed product of R and H if R# σ H becomes an algebra over k by multiplication: (a#h)(b#g) = h,g a(h 1 · b)σ(h 2 , g 1)#h 3 g 2 Let lpd(R M), lid(R M) and lf d(R M) denote the left projective dimension, left injective dimension and left flat dimension of left R-module M, resp...

N ov 2 00 7 CATEGORICAL LANDSTAD DUALITY FOR ACTIONS

We show that the category A(G) of actions of a locally compact group G on C∗-algebras (with equivariant nondegenerate ∗-homomorphisms into multiplier algebras) is equivalent, via a full-crossed-product functor, to a comma category of maximal coactions of G under the comultiplication (C∗(G), δG); and also that A(G) is equivalent, via a reduced-crossed-product functor, to a comma category of norm...

N ov 2 00 5 Statistics on Wreath Products

N ov 2 00 8 Compressed word problems in HNN - extensions and amalgamated products

It is shown that the compressed word problem for an HNNextension 〈H, t | tat = φ(a)(a ∈ A)〉 with A finite is polynomial time Turing-reducible to the compressed word problem for the base group H . An analogous result for amalgamated free products is shown as well.

ar X iv : h ep - p h / 00 11 16 3 v 3 2 8 N ov 2 00 0 SLAC - PUB - 8707 hep - ph / 0011163 November 2000 Challenges in

We give an personal overview of some of the unsolved problems related to hyperon decays. We cover nonleptonic decays, radiative decays and magnetic moments. Some of the theoretical issues are also touched upon.