\proof{
Consider some $D \le C$. If $D = C$, $\isforeign{D}$ trivially.
If $D \neq C$ then $D \le A$ where $A \in \set A$. By Foreign
\proof{
Consider some $D \le C$. If $D = C$, $\isforeign{D}$ trivially.
If $D \neq C$ then $D \le A$ where $A \in \set A$. By Foreign