fact: Definition nat_test_eq a b := ite_rel (a-b) (b-a) 1.
imports: Arith List Lia Undecidability.Shared.Libs.DLW(utils_tac utils_nat utils_list gcd crt sums finite pos vec) Undecidability.MuRec.Util(recalg recomp prim_min)