fact: Definition catf (f g : {fmap K -> V}) := [fmap k : (domf f `\` domf g) `|` domf g=> match fsetULVR (valP k) with | inl kfDg => f.[fsubsetP (fsubsetDl _ _) _ kfDg] | inr kg => g.[kg] end].
imports: HB(structures) mathcomp(ssreflect ssrbool ssrnat eqtype ssrfun seq) mathcomp(choice path finset finfun fintype bigop)