Generation type inequalities for closed linear operators related to domains with conical points

Let ${cal A}(x;D_x)$ be a second-order linear differential operator in divergence form. We prove that the operator ${l}I- {cal A}(x;D_x)$, where $lincsp$ and $I$ stands for the identity operator, is closed and injective when ${rm Re}l$ is large enough and the domain of ${cal A}(x;D_x)$ consists of a special class of weighted Sobolev function spaces related to conical open bounded sets of $rsp^n$, $n ge 1$.