Section EquivalenceUpToTaus.
Context {E : Type -> Type} {R : Type}.
(** The standard [itree] equivalence: "Equivalence Up To Taus", or _weak bisimulation_. *)
Definition eutt : itree E R -> itree E R -> Prop :=
ITree.Eq.Eq.eutt eq.
Infix "≈" := eutt (at level 40).
(** [eutt] is an equivalence relation. *)
Global Instance Equivalence_eutt : Equivalence eutt.

(** We can erase taus unter [eutt]. *)
Lemma tau_eutt : forall (t : itree E R),
Tau t ≈ t.