Hadamard ranks of algebraic varieties

Fuente: arXiv
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Hauptverfasser: Antolini, Dario, Montúfar, Guido, Oneto, Alessandro
Format: Preprint
Veröffentlicht: 2025
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author Antolini, Dario
Montúfar, Guido
Oneto, Alessandro
author_facet Antolini, Dario
Montúfar, Guido
Oneto, Alessandro
contents Motivated by the study of decompositions of tensors as Hadamard products (i.e., coefficient-wise products) of low-rank tensors, we introduce the notion of Hadamard rank of a given point with respect to a projective variety: if it exists, it is the smallest number of points in the variety such that the given point is equal to their Hadamard product. We prove that if the variety $X$ is not contained in a coordinate hyperplane or a binomial hypersurface, then the generic point has a finite $X$-Hadamard-rank. Although the Hadamard rank might not be well defined for special points, we prove that the general Hadamard rank with respect to secant varieties of toric varieties is finite and the maximum Hadamard rank for points with no coordinates equal to zero is at most twice the generic rank. In particular, we focus on Hadamard ranks with respect to secant varieties of toric varieties since they provide a geometric framework in which Hadamard decompositions of tensors can be interpreted. Finally, we give a lower bound to the dimension of Hadamard products of secant varieties of toric varieties: this allows us to deduce the general Hadamard rank with respect to secant varieties of several Segre-Veronese varieties.
format Preprint
id arxiv_https___arxiv_org_abs_2510_05231
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Hadamard ranks of algebraic varieties
Antolini, Dario
Montúfar, Guido
Oneto, Alessandro
Algebraic Geometry
Statistics Theory
14M99, 14N07, 14M25 (Primary) 62E10 (Secondary)
Motivated by the study of decompositions of tensors as Hadamard products (i.e., coefficient-wise products) of low-rank tensors, we introduce the notion of Hadamard rank of a given point with respect to a projective variety: if it exists, it is the smallest number of points in the variety such that the given point is equal to their Hadamard product. We prove that if the variety $X$ is not contained in a coordinate hyperplane or a binomial hypersurface, then the generic point has a finite $X$-Hadamard-rank. Although the Hadamard rank might not be well defined for special points, we prove that the general Hadamard rank with respect to secant varieties of toric varieties is finite and the maximum Hadamard rank for points with no coordinates equal to zero is at most twice the generic rank. In particular, we focus on Hadamard ranks with respect to secant varieties of toric varieties since they provide a geometric framework in which Hadamard decompositions of tensors can be interpreted. Finally, we give a lower bound to the dimension of Hadamard products of secant varieties of toric varieties: this allows us to deduce the general Hadamard rank with respect to secant varieties of several Segre-Veronese varieties.
title Hadamard ranks of algebraic varieties
topic Algebraic Geometry
Statistics Theory
14M99, 14N07, 14M25 (Primary) 62E10 (Secondary)
url https://arxiv.org/abs/2510.05231