标题:Some results on composition operators on <mml:math alttext="$\ell^2$" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mi>ℓ</mml:mi><mml:mn>2</mml:mn></mml:msup></mml:math>
期刊名称:International Journal of Mathematics and Mathematical Sciences
印刷版ISSN:0161-1712
电子版ISSN:1687-0425
出版年度:1979
卷号:2
DOI:10.1155/S016117127900003X
出版社:Hindawi Publishing Corporation
摘要:A necessary and sufficient condition for a bounded operator to be a
composition operator is investigated in this paper. Normal, quasi-hyponormal, paranormal composition operators are characterised.