proposition: Lemma ptrK x i j : (x.+i == x.+j) = (i == j).
proof: Proof. by case: x=>x; rewrite ptrE eqn_add2l. Qed.
imports: Coq(ssreflect ssrbool ssrfun Eqdep) mathcomp(ssrnat eqtype seq path) pcm(options axioms finmap) pcm(pcm unionmap)