proposition: Lemma dom_inNL k f1 f2 : valid (f1 \+ f2) -> k \in dom f1 -> k \notin dom f2.
proof: Proof. by case: validUn=>//_ _ H _; apply: H. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)