Minimal degenerations of orbits of skew-symmetric matrix pencils

Fuente: arXiv
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Main Authors: Das, Sweta, Dmytryshyn, Andrii
Format: Preprint
Published: 2025
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_version_ 1866909876251262976
author Das, Sweta
Dmytryshyn, Andrii
author_facet Das, Sweta
Dmytryshyn, Andrii
contents Complete eigenstructure, e.g., eigenvalues with multiplicities and minimal indices, of a skew-symmetric matrix pencil may change drastically if the matrix coefficients of the pencil are subjected to (even small) perturbations. These changes can be investigated qualitatively by constructing the stratification (closure hierarchy) graphs of the congruence orbits of the pencils. The results of this paper facilitate the construction of such graphs by providing all closest neighbours for a given node in the graph. More precisely, we prove a necessary and sufficient condition for one congruence orbit of a skew-symmetric matrix pencil, A, to belong to the closure of the congruence orbit of another pencil, B, such that there is no pencil, C, whose orbit contains the closure of the orbit of A and is contained in the closure of the orbit of B.
format Preprint
id arxiv_https___arxiv_org_abs_2510_25482
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Minimal degenerations of orbits of skew-symmetric matrix pencils
Das, Sweta
Dmytryshyn, Andrii
Representation Theory
15A22, 15A21, 15A18
Complete eigenstructure, e.g., eigenvalues with multiplicities and minimal indices, of a skew-symmetric matrix pencil may change drastically if the matrix coefficients of the pencil are subjected to (even small) perturbations. These changes can be investigated qualitatively by constructing the stratification (closure hierarchy) graphs of the congruence orbits of the pencils. The results of this paper facilitate the construction of such graphs by providing all closest neighbours for a given node in the graph. More precisely, we prove a necessary and sufficient condition for one congruence orbit of a skew-symmetric matrix pencil, A, to belong to the closure of the congruence orbit of another pencil, B, such that there is no pencil, C, whose orbit contains the closure of the orbit of A and is contained in the closure of the orbit of B.
title Minimal degenerations of orbits of skew-symmetric matrix pencils
topic Representation Theory
15A22, 15A21, 15A18
url https://arxiv.org/abs/2510.25482