English
If F is definable and xs, ys are indexwise equivalent, then out F xs ≈ out F ys.
Русский
Если F определима, и xs, ys эквивалентны по каждому индексу, то out F xs эквивалентно out F ys.
LaTeX
$$$$ \forall n (f : (Fin n → ZFSet) → ZFSet) [Definable n f] {xs ys : Fin n → PSet} (h : \forall i, xs i ≈ ys i) : out f xs ≈ out f ys. $$$$
Lean4
theorem out_equiv {n} (f : (Fin n → ZFSet.{u}) → ZFSet.{u}) [Definable n f] {xs ys : Fin n → PSet}
(h : ∀ i, xs i ≈ ys i) : out f xs ≈ out f ys :=
by
rw [← Quotient.eq_iff_equiv, mk_eq, mk_eq, mk_out, mk_out]
exact congrArg _ (funext fun i ↦ Quotient.sound (h i))