arXiv subjects
Publications and source records attributed to O. G. Styrt.
In the paper, groups $\Gamma_n^4$ closely connected with braid groups are researched from algebraic point of view. More exactly, for $n\geqslant7$, it is proved that $\Gamma_n^4$ is a nilpotent finite $2$-group with $4$-torsion and that its subgroup $(\Gamma_n^4)'$ is central.
An equivalent condition for the product of elements of an independent random sample on a compact algebraic group converging in distribution to some random variable as the sample size increases is obtained. Namely, a limit distribution exists and is uniform on the support of the parent distribution if a random variable with such a distribution does not belong with the unit probability to any non-trivial coset over an algebraic subgroup that lies in its normalizer; otherwise, it does not exist.
The paper is devoted to studying the orthogonality graph of the matrix ring over a commutative ring. It is proved that the orthogonality graph of the ring of matrices with size greater than 1 over a commutative ring with zero-divisors is connected and has diameter 3 or 4; a criterion for each value is obtained. It is also shown that each of its vertices has distance at most 2 from some scalar matrix.
An equivalent condition for an element of a Lie algebra acting nilpotently in all its representations is obtained. Namely, it should belong to the derived algebra and go via factoring over the radical to a nilpotent element of the corresponding (semisimple) quotient algebra.
Subsets of a matrix algebra over a field that are invariant under conjugation and contain the linear span of each two of their commuting elements are described. They obviously include the subsets of diagonalizable and nilpotent matrices. In the paper, the case of an algebraically closed field is considered. The problem is easily reduced to description of subsets of diagonalizable matrices and subsets of nilpotent matrices with the given properties. So, among diagonalizable matrices, there are four of such subsets. As for the nilpotent case, it is proved that the subset should be defined by the condition that the sizes of all Jordan cells of the matrix belong to a certain number set. An explicit criterion is obtained in terms of this set.
The article is devoted to the question whether the orbit space of a compact linear group is a topological manifold and a homological manifold. In the paper, the case of a simple three-dimensional group is considered. An upper bound is obtained for the sum of the half-dimension integral parts of the irreducible components of a representation whose quotient space is a homological manifold, that enhances an earlier result giving the same bound if the quotient space of a representation is a smooth manifold. The most of the representations satisfying this bound are also researched before. In the proofs, standard arguments from linear algebra, theory of Lie groups and algebras and their representations are used.
The problem in question is whether the quotient space of a compact linear group is a topological manifold and whether it is a homological manifold. In the paper, the case of an infinite group with commutative connected component is considered.
It is proved that each of compact linear groups of one special type admits a semialgebraic continuous factorization map onto a real vector space.
We study the question of whether the topological quotient of a real linear representation of a simple three-dimensional compact Lie group is a manifold. We obtain an upper bound for the dimension of a representation whose quotient is a manifold, and examine most of the remaining cases.
It is proved that the orbit space of an irreducible representation of a simple connected compact Lie group of type B, C, or D can be a smooth manifold only in two cases.
It is proved that each of compact linear groups of one special type admits a polynomial factorization map onto a real vector space. More exactly, the group is supposed to be non-commutative one-dimensional and to have two connected components, and its representation should be the direct sum of three irreducible two-dimensional real representations at least two of them being faithful.
This paper is devoted to the study of topological quotients of compact linear Lie groups. More precisely, it investigates the question of when such a quotient is a topological or a smooth manifold. The topological quotient of a finite linear group was studied by Mikhailova in 1984. Here the connected component of the original Lie group G is assumed to be a torus of positive dimension.
Sufficient conditions are obtained for the existence of a vector with a one-dimensional or simple three-dimensional stationary subalgebra for an irreducible compact linear Lie algebra.
We prove that the quotient of an irreducible representation of a special unitary group of rank greater than 1 cannot be a smooth manifold.