proposition: Lemma valid3 (x y z : mutex) : valid (x \+ y \+ z) = [&& valid (x \+ y), valid (y \+ z) & valid (x \+ z)].
proof: Proof. by case: x y z=>[||x][||y][||z]. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq) pcm(options prelude pred) pcm(pcm morphism natmap)