fact: Definition fin_t_upto (P : X -> Type) := { l : _ & (forall x, P x -> exists y, y ∈ l /\ R x y) *(forall x y, x ∈ l -> R x y -> P y) }%type.
imports: List Arith Nat Lia Relations Bool Undecidability.Shared.Libs.DLW.Utils(utils_tac utils_list fin_base)