Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Conjugacy and factorization results on matrix groups

100%

Laffey T. J.

Banach Center Publications

1994

tom 30

nr 1

203-221

In this survey paper, we present (mainly without proof) a number of results on conjugacy and factorization in general linear groups over fields and commutative rings. We also present the additive analogue in matrix rings of some of these results. The first section deals with the question of expressing elements in the commutator subgroup of the general linear group over a field as (simple) commutators. In Section 2, the same kind of problem is discussed for the general linear group over a commutative ring. In Section 3, the analogous question for additive commutators is discussed. The case of integer matrices is given special emphasis as this is an area of current interest. In Section 4, factorizations of an element A ∈ GL(n,F) (F a field) in which at least one of the factors preserves some form (e.g. is symmetric or skew-symmetric) is considered. An application to the size of abelian subgroups of finite p-groups is presented. In Section 5, a curious interplay between additive and multiplicative commutators in $M_n(F)$ (F a field) is identified for matrices of small size and a general factorization theorem for a polynomial using conjugates of its companion matrix is presented.

A sparsity result on nonnegative real matrices with given spectrum

100%

Laffey T. J.

Banach Center Publications

1997

tom 38

nr 1

187-191

Let σ=(λ_1,...,λ_n) be the spectrum of a nonnegative real n × n matrix. It is shown that σ is the spectrum of a nonnegative real n × n matrix having at most $(n+1)^2/2-1$ nonzero entries.

Ograniczanie wyników

2 Banach Center Publications

2 Laffey T. J.

1 1997

1 1994

Wyniki wyszukiwania

Conjugacy and factorization results on matrix groups

A sparsity result on nonnegative real matrices with given spectrum