proposition: Lemma ptr_null x m : (x.+m == null) = (x == null) && (m == 0).
proof: Proof. by case: x=>x; rewrite !ptrE addn_eq0. Qed.
imports: Coq(ssreflect ssrbool ssrfun Eqdep) mathcomp(ssrnat eqtype seq path) pcm(options axioms finmap) pcm(pcm unionmap)