proposition: Lemma prop_ofP T F (iF : @in_filter T F) : F (prop_of iF).
proof: Proof. by rewrite prop_ofE; apply: prop_in_filterP_proj. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap generic_quotient) mathcomp(boolp classical_sets functions) mathcomp(cardinality mathcomp_extra fsbigop) reals signed