English
Let i, j ∈ Fin(m) and h with m ≤ n. Then the preimage of the open-open interval Ioo at castLE(h i) to castLE(h j) under castLE(h) equals Ioo(i, j).
Русский
Пусть i, j ∈ Fin(m) и h с m ≤ n. Тогда предобраз интервала Ioo(castLE(h,i), castLE(h,j)) по отображению castLE(h) равен Ioo(i, j).
LaTeX
$$$castLE(h)^{-1}'\mathrm{Ioo}(\mathrm{castLE}(h,i), \mathrm{castLE}(h,j)) = \mathrm{Ioo}(i, j)$$$
Lean4
@[simp]
theorem preimage_castLE_Ioo_castLE (i j : Fin m) (h : m ≤ n) : castLE h ⁻¹' Ioo (castLE h i) (castLE h j) = Ioo i j :=
rfl