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arXiv · 2410.07942

Spaces of triangularizable matrices

Clément de Seguins Pazzis
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Abstract

Let F be a field. We investigate the greatest possible dimension t_n(F) for a vector space of n-by-n matrices with entries in F and in which every element is triangularizable over the ground field F. It is obvious that t_n(F) is greater than or equal to n(n+1)/2, and we prove that equality holds if and only if F is not quadratically closed or n=1, excluding finite fields with characteristic 2. If F is infinite and not quadratically closed, we give an explicit description of the solutions with the critical dimension t_n(F), reducing the problem to the one of deciding for which integers k between 2 and n all k-by-k symmetric matrices over F are triangularizable.

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Clément de Seguins Pazzis. 2024-10-10. Spaces of triangularizable matrices. https://arxiv.org/abs/2410.07942

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