A treatment of the Cauchy-Schwarz inequality in C*-modules (CROSBI ID 150234)
Prilog u časopisu | izvorni znanstveni rad | međunarodna recenzija
Podaci o odgovornosti
Arambašić, Ljiljana ; Bakić, Damir ; Moslehian, Sal Mohammad
engleski
A treatment of the Cauchy-Schwarz inequality in C*-modules
We study the Cauchy-Schwarz and some related inequalities in a semi-inner product module over a C*-algebra A. The key idea is to consider a semi-inner product A-module as a semi-inner product A-module with respect to another semi-inner product. In this way, we improve some inequalities such as the Ostrowski inequality and an inequality related to the Gram matrix. The induced semi-inner products are also related to the the notion of covariance and variance. Furthermore, we obtain a sequence of nested inequalities that emerges from the Cauchy-Schwarz inequality. As a consequence, we derive some interesting operator-theoretical corollaries. In particular, we show that the sequence arising from our construction, when applied to a positive invertible element of a C*-algebra, converges to its inverse.
C*-algebra ; semi-inner product C*-module ; Cauchy-Schwarz inequality ; Gram matrix
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Podaci o izdanju
381 (2)
2011.
546-556
objavljeno
0022-247X
1096-0813
10.1016/j.jmaa.2011.02.062