Section SUTT_facts.
Context {E : Type -> Type} {R1 R2 : Type} (RR : R1 -> R2 -> Prop).

Theorem sutt_eutt {E R1 R2} (RR : R1 -> R2 -> Prop) :
forall (t1 : itree E R1) (t2 : itree E R2),
sutt RR t1 t2 -> sutt (flip RR) t2 t1 -> eutt RR t1 t2.