How could you prove:
An edge (u,v) is part of an undirected graph G. If post(u) $<$ post(v) (i.e. the post number of u is smaller than that of v) then it implies that v is an ancestor of u in the DFS tree.
So far I have understood that it does in fact imply that so I need to prove this. I have thought of doing it by contradiction but not exactly sure how I would go about doing that.