English
The inverse image of None under consEquiv is the pair ⟨v, ⟨m.count v, h⟩⟩ where h expresses the appropriate bound.
Русский
Образ обратной карты None через consEquiv есть пара ⟨v, ⟨m.count v, h⟩⟩, где h задаёт нужное ограничение.
LaTeX
$$$ (consEquiv (m := m) (v := v)).symm None = \langle v, \langle m.\mathrm{count} v, (count\_cons\_self v m) \rhd (\mathrm{Nat}.lt\_add\_one)\rangle \rangle $$$
Lean4
@[simp]
theorem consEquiv_symm_none {v : α} :
(consEquiv (m := m) (v := v)).symm none = ⟨v, ⟨m.count v, (count_cons_self v m) ▸ (Nat.lt_add_one _)⟩⟩ :=
rfl