Weighted Sobolev spaces, capacities and exceptional sets

We consider the weighted Sobolev space $W^{m,p}_\omega (\Omega)$, where $\Omega$ is an open subset of $R^n$, $n\ge2$, and $\omega$ is a Muckenhoupt $A_p$-weight on $R^n$, $1\le p<\infty$, $m\in\mathbb N$. For the equalities $W^{m,p}_\omega (\Omega\setminus E)=W^{m,p}_\omega(\Omega)$, $W^{m,p}_\omega(\Omega\setminus E)=W^{m,p}_\omega(\Omega)$ to hold, conditions are obtained in terms of $E$ as a set of zero $(p,m,\omega)$-capacity, or an $NC_{p,\omega}$-set for the first equality. For the equality $W^{m,p}(\Omega)=W^{m,p}(\Omega)$, the conditions are established for $R^n \setminus\Omega$ as a set of zero $(p,m,\omega)$-capacity. Similar results are partially true for $W^m_{p,\omega}(\Omega)$, $L^m_{p,\omega}(\Omega)$.