On the numerical index with respect to an operator

Vladimir Kadets, Miguel Martin, Javier Meri +2

Given Banach spaces $X$ and $Y$, and a norm-one operator $G\in \mathcal{L}(X,Y)$, the numerical index with respect to $G$, $n_G(X,Y)$, is the greatest constant $k\ge 0$ such that…