首页 | 本学科首页   官方微博 | 高级检索  
     


A counter-example to a conjecture of Friedland
Authors:Takashi Yoshino
Affiliation:1. Department of Mathematics, College of General Education, T?hoku University, Kawauchi, Aoba-ku, 980, Sendai, Japan
Abstract:
In 1982, S. Friedland proved that a bounded linear operator A on a Hilbert space is normal if and only if (αI + A + A*)2 ≧ AA* − A*A ≧ −(αI + A + A*)2 for all real α. And he conjectured the inequality (αI + A + A*)2 ≧ AA* − A*A for all real α will imply that A*A − AA* ≧ 0, i.e., A is hyponormal. But his conjecture is incorrect. In this note I’ll give a counter-example for his conjecture.
Keywords:
本文献已被 SpringerLink 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号