fact: Fixpoint ra_inject n : recalg n.
imports: Arith Lia Undecidability.Shared.Libs.DLW.Utils(utils_tac utils_nat gcd crt sums) Undecidability.Shared.Libs.DLW.Vec(pos vec) Undecidability.MuRec.Util(recalg recomp prim_min ra_utils)