proposition: Lemma valid_sep2P (x y : U) : valid (x \+ y) -> D (pval x) (pval y).
proof: Proof. by rewrite valid_sep; case/andP. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(eqtype fintype) pcm(options axioms prelude) pcm(pcm)