proposition: Lemma dom_inIL k f1 f2 : valid (f1 \+ f2) -> k \in dom f1 -> k \in dom (f1 \+ f2).
proof: Proof. by rewrite domUn inE => ->->. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)