id : ?M_1 → ?M_1
trans : (?M_1 → ?M_1 → Prop) → Prop
symm : (?M_1 → ?M_1 → Prop) → Prop
equivalence : (?M_1 → ?M_1 → Prop) → Prop
λ (A : Type) (R : A → A → Prop),
  and (and (refl R) (symm R)) (trans R)
