English
For any α, n, a, s, the equality (a :: symEquivSym' s) = symEquivSym' (a ::ₛ s) holds, i.e., the cons operation commutes with the equivalence between Sym and Sym'.
Русский
Для любых α, n, a, s равенство (a :: symEquivSym' s) = symEquivSym' (a ::ₛ s) справедливо; то есть конc и эквив когерентны.
LaTeX
$$$ a ::\, \mathrm{symEquivSym'}(s) = \mathrm{symEquivSym'}(a ::ₛ s). $$$
Lean4
theorem cons_equiv_eq_equiv_cons (α : Type*) (n : ℕ) (a : α) (s : Sym α n) :
(a :: symEquivSym' s) = symEquivSym' (a ::ₛ s) :=
by
rcases s with ⟨⟨l⟩, _⟩
rfl