According to [1]}, we may let \(\hat{u} \in H^1_0(\mathbb {R}^n)\cap L^{\infty }(\mathbb {R}^n)\)  be an extension of \(u\)  such that \(\hat{u}=u\)  in \(\Omega \)  and
\(\Vert \hat{u} \Vert _{H^1(\mathbb {R}^n)} \le C(n,\Omega ) \Vert u \Vert _{H^1(\Omega )}.\) 

Согласно \cite{1}, мы можем позволить \(\hat{u} \in H^1_0(\mathbb {R}^n)\cap L^{\infty }(\mathbb {R}^n)\) быть расширением \(u\) таким, что \(\hat{u}=u\) в \(\Omega \) и \(\Vert \hat{u} \Vert _{H^1(\mathbb {R}^n)} \le C(n,\Omega ) \Vert u \Vert _{H^1(\Omega )}.\)