We construct a dynamical lattice model based on crossed module of possibly non-abelian finite groups. Its degrees freedom are defined links and plaquettes, while gauge transformations vertices the underlying lattice. specify Hilbert space, define basic observables (including Hamiltonian) initiate a~discussion model's phase diagram. The constructed generalizes, in appropriate limits reduces to, ...

It is well known that the homotopy category of connected CW-complexes X whose homotopy groups n;(X) are trivial for i> 1 is equivalent to the category of groups. One of the objects of this paper is to prove a similar equivalence for the connected CW-complexes X whose homotopy groups are trivial for i > n + 1 (where n is a fixed non-negative integer). For n = 1 the notion of crossed module inven...

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...

It is a well-known result of the covering groups that a subgroup G of the fundamental group at the identity of a semilocally simply connected topological group determines a covering morphism of topological groups with characteristic group G . In this paper we generalize this result to a large class of algebraic objects called topological groups with operations, including topological groups. We ...

The universal C*-algebra generated by n projections has been described. As an immediate corollary one obtains structure theorem for a pair of projections and the solution to an associated index problem. This puts the study of a pair of projections in the proper perspective of noncommutative geometry. keyword: Index problem, crossed product, Fredholm module, pair of projections. MSC 46L87.

A computer storage system which is addressed by content rather than location is described. The design has been verified by constructing and successfully operating a three-word module consisti~g of 81 crossed-film cryotrons on a 6-inch by 3-inch substrate.

Let H be a Hopf algebra. Ju and Cai introduced the notion of twisting of an H-module coalgebra. In this note, we study the relationship between twistings, crossed coproducts and Hopf-Galois coextensions. In particular, we show that a twisting of an H-Galois coextension remains H-Galois if the twisting is invertible.

We analzye Rieffel’s construction of generalized fixed point algebras in the setting of group actions on Hilbert modules. Let G be a locally compact group acting on a C∗-algebra B. We construct a Hilbert module F over the reduced crossed product of G and B, using a pair (E, R), where E is an equivariant Hilbert module over B and R is a dense subspace of E with certain properties. The generalize...

Given a crossed module of groupoids [Formula: see text], we construct (1) natural homomorphism from the product groupoid text] to and (2) transgression map singular cohomology nerve text]. The latter turns out be identical obtained by Tu–Xu in their study equivariant text]-theory.

The aim of this paper is to show one more facet of the role of crossed complexes as generalisations of both groups (or groupoids) and of chain complexes. We do this by defining and establishing the main properties of a classifying space functor B: mia -> SToft from the category of crossed complexes to the category of spaces. The basic example of a crossed complex is the fundamental crossed comp...