Set Implicit Arguments.
Unset Strict Implicit.
Definition cards {X : Type} (x: list X) := map (fun a => ([a], [a])) x.
Hint Resolve sym_word_l sym_word_R : core.
Coercion sing (n : nat) := [n].
From Undecidability.Synthetic Require Import Definitions DecidabilityFacts EnumerabilityFacts ListEnumerabilityFacts.
From Undecidability Require Export PCP.PCP.
From Undecidability.Shared Require Export ListAutomation.

Lemma stack_discrete :
discrete (stack bool).