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arXiv · 1602.08623

On the dimension of the locus of determinantal hypersurfaces

Zinovy Reichstein·Angelo Vistoli
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Abstract

The characteristic polynomial of an $r$-tuple $(A_1,..., A_r)$ of $n \times n$ matrices is the determinant $\det(x_0 I + x_1 A_1 + ... + x_r A_r)$. We show that if $r$ is at least 3 and $A = (A_1,..., A_r)$ is an $r$-tuple of matrices in general position, then up to conjugacy there are only finitely many $r$-tuples of matrices with the same characteristic polynomial as $A$. Equivalently, the locus of determinantal hypersurfaces of degree $n$ in $P^r$ is irreducible of dimension $(r-1)n^2 + 1$.

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Zinovy Reichstein, Angelo Vistoli. 2016-02-27. On the dimension of the locus of determinantal hypersurfaces. https://doi.org/10.4153/cmb-2016-070-8

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