proposition: Lemma hcancelT A1 A2 x (v1 : A1) (v2 : A2) h1 h2 : valid (x :-> v1 \+ h1) -> x :-> v1 \+ h1 = x :-> v2 \+ h2 -> A1 = A2.
proof: Proof. by move=>V; case/(cancel V); move/dyn_injT. Qed.
imports: Coq(ssreflect ssrbool ssrfun Eqdep) mathcomp(ssrnat eqtype seq path) pcm(options axioms finmap) pcm(pcm unionmap)