Open AccessOn a question of Mecheri and Braha
Author(s) -
Qingping Zeng,
Huaijie Zhong
Publication year - 2013
Publication title -
filomat
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.449
H-Index - 34
eISSN - 2406-0933
pISSN - 0354-5180
DOI - 10.2298/fil1306057z
Subject(s) - mathematics , spectrum (functional analysis) , combinatorics , point (geometry) , pure mathematics , discrete mathematics , geometry , quantum mechanics , physics
In this note we give an answer to a question posed recently by Mecheri and Braha [Oper. Matrices 6 (2012), 725-734]. More precisely, we show that if T is n-perinormal, then the nonzero points λ of its approximate point spectrum and joint approximate point spectrum are identical; but this is not the case when λ = 0.
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