fact: Variable (sig : IMSELL_sig) (a b i : sig).
imports: List Permutation Arith Lia Undecidability.MinskyMachines(ndMM2) Undecidability.ILL(IMSELL imsell) Undecidability.Shared.Libs.DLW(utils pos vec) Undecidability.Synthetic(Definitions ReducibilityFacts)