fact: Definition abst_impl (pol : bool) (o :option AF) (k: kind) (f1 f2:TFormula TX AF k) : TFormula TX AF k:= (if pol then abs_or else abs_and) k (REC (negb pol) f1) (REC pol f2) (mk_arrow o).
imports: List Refl Bool Relation_Definitions Setoid