Formulas for the eigendiscriminants of ternary and quaternary forms - Archive ouverte HAL Access content directly
Journal Articles Linear and Multilinear Algebra Year : 2022

Formulas for the eigendiscriminants of ternary and quaternary forms

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Laurent Busé

Abstract

A $d$-dimensional tensor $A$ of format $n\times n\times \cdots \times n$ defines naturally a rational map $\Psi$ from the projective space $\mathbb{P}^{n-1}$ to itself and its eigenscheme is then the subscheme of $\mathbb{P}^{n-1}$ of fixed points of $\Psi$. The eigendiscriminant is an irreducible polynomial in the coefficients of $A$ that vanishes for a given tensor if and only if its eigenscheme is singular. In this paper we contribute two formulas for the computation of eigendiscriminants in the cases $n=3$ and $n=4$. In particular, by restriction to symmetric tensors, we obtain closed formulas for the eigendiscriminants of plane curves and surfaces in $\mathbb{P}^3$ as the ratio of some determinants of resultant matrices.

Dates and versions

hal-02881339 , version 1 (25-06-2020)

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Cite

Laurent Busé. Formulas for the eigendiscriminants of ternary and quaternary forms. Linear and Multilinear Algebra, In press, ⟨10.1080/03081087.2022.2075819⟩. ⟨hal-02881339⟩
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