2,424 research outputs found
Computing generators of the unit group of an integral abelian group ring
We describe an algorithm for obtaining generators of the unit group of the
integral group ring ZG of a finite abelian group G. We used our implementation
in Magma of this algorithm to compute the unit groups of ZG for G of order up
to 110. In particular for those cases we obtained the index of the group of
Hoechsmann units in the full unit group. At the end of the paper we describe an
algorithm for the more general problem of finding generators of an arithmetic
group corresponding to a diagonalizable algebraic group
Fock factorizations, and decompositions of the spaces over general Levy processes
We explicitly construct and study an isometry between the spaces of square
integrable functionals of an arbitrary Levy process and a vector-valued
Gaussian white noise. In particular, we obtain explicit formulas for this
isometry at the level of multiplicative functionals and at the level of
orthogonal decompositions, as well as find its kernel. We consider in detail
the central special case: the isometry between the spaces over a Poisson
process and the corresponding white noise. The key role in our considerations
is played by the notion of measure and Hilbert factorizations and related
notions of multiplicative and additive functionals and logarithm. The obtained
results allow us to introduce a canonical Fock structure (an analogue of the
Wiener--Ito decomposition) in the space over an arbitrary Levy process.
An application to the representation theory of current groups is considered. An
example of a non-Fock factorization is given.Comment: 35 pages; LaTeX; to appear in Russian Math. Survey
Toward a fundamental groupoid for the stable homotopy category
This very speculative sketch suggests that a theory of fundamental groupoids
for tensor triangulated categories could be used to describe the ring of
integers as the singular fiber in a family of ring-spectra parametrized by a
structure space for the stable homotopy category, and that Bousfield
localization might be part of a theory of `nearby' cycles for stacks or
orbifolds.Comment: This is the version published by Geometry & Topology Monographs on 18
April 200
Clifford Algebraic Remark on the Mandelbrot Set of Two--Component Number Systems
We investigate with the help of Clifford algebraic methods the Mandelbrot set
over arbitrary two-component number systems. The complex numbers are regarded
as operator spinors in D\times spin(2) resp. spin(2). The thereby induced
(pseudo) normforms and traces are not the usual ones. A multi quadratic set is
obtained in the hyperbolic case contrary to [1]. In the hyperbolic case a
breakdown of this simple dynamics takes place.Comment: LaTeX, 27 pages, 6 fig. with psfig include
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