k-Quasihyponormal operators are subscalar

被引:5
|
作者
Ko, E
机构
[1] Ewha Women's University,Department of Mathematics
关键词
D O I
10.1007/BF01309158
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
In this paper we shall prove that if an operator T is an element of L(+H-2(1)) is an operator matrix of the form T = (0T(1) T3T2) where T-1 is hyponormal and T-3(K) = 0, then T is subscalar of order 2(k+1). Hence non-trivial invariant subspaces are known to exist if the spectrum of T has interior in the plane as a result of a theorem of Eschmeier and Prunarn (see [EP]). As a corollary we get that any k-quasihyponormal operators are subscalar.
引用
收藏
页码:492 / 499
页数:8
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