Samir ElMohammady Nssar

For a given bounded positive (semidefinite) linear operator A on a complex Hilbert space
H , we consider the semi-Hilbertian space (H,(,)_A). The A-numerical radius of an A-bounded operator
T on H is denoted by \omega_A(T).
In this project, we prove some upper and lower bounds for the $A$- numerical radius of
the off-diagonal part of 3 × 3 operator matrices and some $A$- bounds for the $A$-numerical
radius inequalities of the general 3 × 3 operator matrix, where $A=diag(A,A)$