Complete invariants for simultaneous similarity

Fuente: arXiv
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Main Authors: Bongartz, Klaus, Friedland, Shmuel
Format: Preprint
Published: 2026
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author Bongartz, Klaus
Friedland, Shmuel
author_facet Bongartz, Klaus
Friedland, Shmuel
contents Always dealing with an arbitrary field we consider the variety $(k^{n\times n})^{p}$ under the action of $GL_{n}$ by simultaneous similarity. We define discrete and continuous invariants which completely determine the orbits. The discrete invariants induce a disjoint decomposition of the variety into finitely many locally closed $GL_{n}$-stable subsets and for each of these we construct finitely many invariant morphisms to $k$ separating the orbits. The complicated action of $GL_{n}$ by similarity is reduced to left multiplication of a product of $GL_{l_{i}}$'s on a product of $k^{l_{i}\times m_{i}}$'s. An analogous result holds for the left-right action of $GL_{m}\times GL_{n}$ on $(k^{m\times n })^{p}$ and more generally for all varieties of finite dimensional modules over some finitely generated algebra.
format Preprint
id arxiv_https___arxiv_org_abs_2601_00379
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Complete invariants for simultaneous similarity
Bongartz, Klaus
Friedland, Shmuel
Representation Theory
14L24, 14L30, 15A21, 16G20, 32S60
Always dealing with an arbitrary field we consider the variety $(k^{n\times n})^{p}$ under the action of $GL_{n}$ by simultaneous similarity. We define discrete and continuous invariants which completely determine the orbits. The discrete invariants induce a disjoint decomposition of the variety into finitely many locally closed $GL_{n}$-stable subsets and for each of these we construct finitely many invariant morphisms to $k$ separating the orbits. The complicated action of $GL_{n}$ by similarity is reduced to left multiplication of a product of $GL_{l_{i}}$'s on a product of $k^{l_{i}\times m_{i}}$'s. An analogous result holds for the left-right action of $GL_{m}\times GL_{n}$ on $(k^{m\times n })^{p}$ and more generally for all varieties of finite dimensional modules over some finitely generated algebra.
title Complete invariants for simultaneous similarity
topic Representation Theory
14L24, 14L30, 15A21, 16G20, 32S60
url https://arxiv.org/abs/2601.00379