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Square roots of hyponormal operators
- Title
- Square roots of hyponormal operators
- Authors
- Kim, MK; Ko, E
- Ewha Authors
- 고응일
- SCOPUS Author ID
- 고응일

- Issue Date
- 1999
- Journal Title
- GLASGOW MATHEMATICAL JOURNAL
- ISSN
- 0017-0895
- Citation
- GLASGOW MATHEMATICAL JOURNAL vol. 41, pp. 463 - 470
- Publisher
- CAMBRIDGE UNIV PRESS
- Indexed
- SCIE; SCOPUS

- Document Type
- Article
- Abstract
- An operator T is an element of L(H) is called a square root of a hyponormal operator if T-2 is hyponormal. In this paper, we prove the following results: Let S and T be square roots of hyponormal operators. (1) If sigma(T) boolean AND [-sigma(T)] = phi or {0}, then T is isoloid (i.e., every isolated point of sigma(T) is an eigenvalue of T). (2) If S and T commute, then ST is Weyl if and only if S and T are both Weyl. (3) If sigma(T) boolean AND [-sigma(T)] = phi, or {0}, then Weyl's theorem holds for T. (4) If sigma(T) boolean AND [-sigma(T)] = phi, then T is subscalar. As a corollary, we get that T has a nontrivial invariant subspace if sigma(T) has non-empty interior. (See [3].).
- DOI
- 10.1017/S0017089599000178
- Appears in Collections:
- 자연과학대학 > 수학전공 > Journal papers
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