fact: Parameter imfset2 : forall (key : unit) (K T1 : choiceType) (T2 : T1 -> choiceType)(f : forall x : T1, T2 x -> K) (p1 : finmempred T1) (p2 : forall x : T1, finmempred (T2 x)), phantom (mem_pred T1) p1 -> phantom (forall x, mem_pred (T2 x)) p2 -> {fset K}.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrnat eqtype ssrfun seq) mathcomp(choice path finset finfun fintype bigop)