An Algorithm for Diagonalizing Matrices of Formal Power Series

Fuente: arXiv
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Autori principali: Dai, Zihao, Liang, Hao, Lu, Jingyu, Zhi, Lihong
Natura: Preprint
Pubblicazione: 2026
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author Dai, Zihao
Liang, Hao
Lu, Jingyu
Zhi, Lihong
author_facet Dai, Zihao
Liang, Hao
Lu, Jingyu
Zhi, Lihong
contents This paper studies the unitary diagonalization of matrices over formal power series rings. Our main result shows that a normal matrix is unitarily diagonalizable if and only if its minimal polynomial completely splits over the ring and the associated spectral projections have entries in the ring. Building on this characterization, we develop an algorithm for deciding the unitary diagonalizability of matrices over regular local rings of algebraic varieties. A central ingredient of the algorithm is a decision procedure for determining whether a polynomial splits over a formal power series ring; we establish this using techniques from prime decomposition and the relative smoothness of integral closures in ramification theory.
format Preprint
id arxiv_https___arxiv_org_abs_2602_08313
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle An Algorithm for Diagonalizing Matrices of Formal Power Series
Dai, Zihao
Liang, Hao
Lu, Jingyu
Zhi, Lihong
Commutative Algebra
Algebraic Geometry
This paper studies the unitary diagonalization of matrices over formal power series rings. Our main result shows that a normal matrix is unitarily diagonalizable if and only if its minimal polynomial completely splits over the ring and the associated spectral projections have entries in the ring. Building on this characterization, we develop an algorithm for deciding the unitary diagonalizability of matrices over regular local rings of algebraic varieties. A central ingredient of the algorithm is a decision procedure for determining whether a polynomial splits over a formal power series ring; we establish this using techniques from prime decomposition and the relative smoothness of integral closures in ramification theory.
title An Algorithm for Diagonalizing Matrices of Formal Power Series
topic Commutative Algebra
Algebraic Geometry
url https://arxiv.org/abs/2602.08313