fact: Definition gamma1 (A : stack nat) := map (fun '(x, y) => (x, (x ++ [#] ++ y ++ [#]))) A.
imports: List Lia Undecidability.CFG.CFP Undecidability.CFG.Util.Facts Undecidability.PCP.PCP Undecidability.PCP.Util.Facts Undecidability.PCP.Util.PCP_facts Undecidability.Synthetic.Definitions