Resolvent set of an operator
= Resolvent set of an operator
{title2=$\rho(A)$}
The resolvent set $\rho(A)$ consists of the complex numbers $z$ for which $zI-A:D(A)\to X$ is bijective and has a bounded inverse on $X$. This inverse is the <resolvent of an element> $R(z,A)=(zI-A)^{-1}$.