fact: Definition P := [d;e] ++ map (fun '(x,y) => (#_L x, #_R y)) (filter (fun '(x,y) => is_cons x || is_cons y) (x0/y0::R)).
imports: Bool List Undecidability.PCP.PCP Undecidability.PCP.Util.Facts Undecidability.PCP.Util.PCP_facts Undecidability.Synthetic.Definitions