Eigenvalues and equivalence classes of third-order symmetric tensors

Fuente: arXiv
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Autori principali: Fang, Lishan, Huang, Hua-Lin, Ruan, Shengyuan, Ye, and Yu
Natura: Preprint
Pubblicazione: 2025
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author Fang, Lishan
Huang, Hua-Lin
Ruan, Shengyuan
Ye, and Yu
author_facet Fang, Lishan
Huang, Hua-Lin
Ruan, Shengyuan
Ye, and Yu
contents This paper demonstrates that third-order real symmetric tensors cannot be classified up to equivalence by their eigenvalues only, thereby resolving a problem posed by Qi in 2006. By applying Harrison's center theory, we derive equivalence classes of $2 \times 2 \times 2$ symmetric tensors via the one-to-one correspondence with the canonical forms of their associated binary cubics. For such tensors, we compute the explicit characteristic polynomials and discover two previously unknown coefficients using the combination resultant. Pairs of third-order real symmetric tensors of all dimensions with identical eigenvalues but belonging to different equivalence classes are constructed to illustrate the inapplicability of eigenvalues for classification.
format Preprint
id arxiv_https___arxiv_org_abs_2512_10263
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Eigenvalues and equivalence classes of third-order symmetric tensors
Fang, Lishan
Huang, Hua-Lin
Ruan, Shengyuan
Ye, and Yu
Rings and Algebras
15A69, 15A21, 15A18, 13P15
This paper demonstrates that third-order real symmetric tensors cannot be classified up to equivalence by their eigenvalues only, thereby resolving a problem posed by Qi in 2006. By applying Harrison's center theory, we derive equivalence classes of $2 \times 2 \times 2$ symmetric tensors via the one-to-one correspondence with the canonical forms of their associated binary cubics. For such tensors, we compute the explicit characteristic polynomials and discover two previously unknown coefficients using the combination resultant. Pairs of third-order real symmetric tensors of all dimensions with identical eigenvalues but belonging to different equivalence classes are constructed to illustrate the inapplicability of eigenvalues for classification.
title Eigenvalues and equivalence classes of third-order symmetric tensors
topic Rings and Algebras
15A69, 15A21, 15A18, 13P15
url https://arxiv.org/abs/2512.10263