11 | Thm* For any graph
the_obj:GraphObject(the_graph), P:(V Traversal Traversal Prop), s:Traversal, i:V. ( s:Traversal, i:V. (inl(i) s) (inr(i) s)  P(i,s,nil))  ( s1,s2,s3:Traversal, i,j:V. i-the_graph- > j  paren(V;s2)  paren(V;s3)  P(j,s1,s2)  P(i,s2 @ s1,s3)  P(i,s1,s3 @ s2))  ( s1,s2:Traversal, i:V. (inl(i) s1)  (inr(i) s1)  P(i,[inr(i) / s1],s2)  P(i,s1,[inl(i) / (s2 @ [inr(i)])]))  ( s':Traversal. P(i,s,s') & l_disjoint(V+V;s';s) & no_repeats(V+V;s') & paren(V;s') & dfs(the_obj;s;i) = (s' @ s)) | [dfs_induction2] |