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Weyl’s Theorem for pairs of commuting hyponormal operators
Journal article   Open access   Peer reviewed

Weyl’s Theorem for pairs of commuting hyponormal operators

Sameer Chavan and Raúl Curto
Proceedings of the American Mathematical Society, Vol.145(8), pp.3369-3375
08/01/2017
DOI: 10.1090/proc/13479
url
https://doi.org/10.1090/proc/13479View
Published (Version of record) Open Access

Abstract

Let T be a pair of commuting hyponormal operators satisfying the so-called quasitriangular property dim ker (T - lambda) >= dim ker (T - lambda)*, for every lambda in the Taylor spectrum sigma(T) of T. We prove that the Weyl spectrum of T, omega(T), satisfies the identity omega(T) = sigma(T)\pi 00( T), where pi 00(T) denotes the set of isolated eigenvalues of finite multiplicity. Our method of proof relies on a (strictly 2-variable) fact about the topological boundary of the Taylor spectrum; as a result, our proof does not hold for d-tuples of commuting hyponormal operators with d > 2.
Mathematics Physical Sciences Mathematics, Applied Science & Technology

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