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arXiv · 2604.07062

Eigenvalue collision and exotic preservers on semisimple operators

Alexandru Chirvasitu
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Abstract

We classify $n\times n$-matrix-valued continuous commutativity and spectrum preservers defined on spaces of (a) normal, (b) semisimple and (c) arbitrary $n\times n$ matrices with spectra contained in sufficiently connected subsets $\mathcal{X}\subseteq \mathbb{C}$, generalizing a number of results due to \v{S}emrl, Gogi\'{c}, Toma\v{s}evi\'c and the author among others. In case (a) these are always conjugations or transpose conjugations, while in cases (b) and (c) qualitatively distinct possibilities arise depending on the local regularity of the complex-conjugation map close to coincident-eigenvalue loci of $\mathcal{X}^n$.

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BibTeXRIS

Alexandru Chirvasitu. 2026-04-08. Eigenvalue collision and exotic preservers on semisimple operators. https://arxiv.org/abs/2604.07062

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