proposition: Lemma dom_inNX k1 k2 f1 f2 : valid (f1 \+ f2) -> k1 \in dom f1 -> k2 \in dom f2 -> k1 <> k2.
proof: Proof. by move=>W K1 K2; apply/eqP; apply: dom_inN K1 K2. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)