fact: Definition G := (S, (S,[S]) :: map (fun '(u, v) => (S, u ++ [S] ++ v)) R ++ map (fun '(u, v) => (S, u ++ [a] ++ v)) R).
imports: Setoid Morphisms List Arith Lia Undecidability.CFG.CFP Undecidability.CFG.CFG Undecidability.CFG.Util.Facts Undecidability.PCP.PCP Undecidability.PCP.Util.PCP_facts Undecidability.Synthetic.Definitions