fact: Hypothesis HP : forall x y, i_P x y -> x =/= i_dum /\ y =/= i_dum.
imports: Lia Arith Undecidability.PCP.PCP Undecidability.PCP.Util.PCP_facts Undecidability.Synthetic.DecidabilityFacts Undecidability(FOL.Utils.FullSyntax) Undecidability(FOL.FSAT) Undecidability.Shared.ListAutomation