Spectra inhabiting the left half-plane that are universally realizable

Let Λ = {λ1, λ2, . . ., λn} be a list of complex numbers. Λ is said to be realizable if it is the spectrum of an entrywise nonnegative matrix. Λ is universally realizable if it is realizable for each possible Jordan canonical form allowed by Λ. Minc ([21],1981) showed that if Λ is diagonalizably pos...

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Main Author: Soto Ricardo L.
Format: Article
Language:English
Published: De Gruyter 2021-12-01
Series:Special Matrices
Subjects:
Online Access:https://doi.org/10.1515/spma-2021-0155
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author Soto Ricardo L.
author_facet Soto Ricardo L.
author_sort Soto Ricardo L.
collection DOAJ
description Let Λ = {λ1, λ2, . . ., λn} be a list of complex numbers. Λ is said to be realizable if it is the spectrum of an entrywise nonnegative matrix. Λ is universally realizable if it is realizable for each possible Jordan canonical form allowed by Λ. Minc ([21],1981) showed that if Λ is diagonalizably positively realizable, then Λ is universally realizable. The positivity condition is essential for the proof of Minc, and the question whether the result holds for nonnegative realizations has been open for almost forty years. Recently, two extensions of the Minc’s result have been proved in ([5], 2018) and ([12], 2020). In this work we characterize new left half-plane lists (λ1 > 0, Re λi ≤ 0, i = 2, . . ., n) no positively realizable, which are universally realizable. We also show new criteria which allow to decide about the universal realizability of more general lists, extending in this way some previous results.
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spelling doaj.art-54f92bab346343a8afe21860ec5d0c1f2022-12-22T02:05:43ZengDe GruyterSpecial Matrices2300-74512021-12-0110118019210.1515/spma-2021-0155Spectra inhabiting the left half-plane that are universally realizableSoto Ricardo L.0Departamento de Matemáticas, Universidad Católica del Norte, Antofagasta, Chile, Casilla 1280, Antofagasta, ChileLet Λ = {λ1, λ2, . . ., λn} be a list of complex numbers. Λ is said to be realizable if it is the spectrum of an entrywise nonnegative matrix. Λ is universally realizable if it is realizable for each possible Jordan canonical form allowed by Λ. Minc ([21],1981) showed that if Λ is diagonalizably positively realizable, then Λ is universally realizable. The positivity condition is essential for the proof of Minc, and the question whether the result holds for nonnegative realizations has been open for almost forty years. Recently, two extensions of the Minc’s result have been proved in ([5], 2018) and ([12], 2020). In this work we characterize new left half-plane lists (λ1 > 0, Re λi ≤ 0, i = 2, . . ., n) no positively realizable, which are universally realizable. We also show new criteria which allow to decide about the universal realizability of more general lists, extending in this way some previous results.https://doi.org/10.1515/spma-2021-0155nonnegative matrixuniversal realizabilityjordan structure15a1815a29
spellingShingle Soto Ricardo L.
Spectra inhabiting the left half-plane that are universally realizable
Special Matrices
nonnegative matrix
universal realizability
jordan structure
15a18
15a29
title Spectra inhabiting the left half-plane that are universally realizable
title_full Spectra inhabiting the left half-plane that are universally realizable
title_fullStr Spectra inhabiting the left half-plane that are universally realizable
title_full_unstemmed Spectra inhabiting the left half-plane that are universally realizable
title_short Spectra inhabiting the left half-plane that are universally realizable
title_sort spectra inhabiting the left half plane that are universally realizable
topic nonnegative matrix
universal realizability
jordan structure
15a18
15a29
url https://doi.org/10.1515/spma-2021-0155
work_keys_str_mv AT sotoricardol spectrainhabitingthelefthalfplanethatareuniversallyrealizable