English
For all m,n and i,j ∈ Fin n, the preimage of the half-open interval (castAdd m i, castAdd m j] under castAdd m is exactly (i, j].
Русский
Для всех m,n и i,j ∈ Fin n, предобраз (castAdd m i, castAdd m j] под castAdd m равен (i, j].
LaTeX
$$$$\\bigl(\\mathrm{Fin.castAdd}\\, m\\bigr)^{-1}\\bigl(\\mathrm{Ioc}(\\mathrm{Fin.castAdd}\\, m\\, i, \\mathrm{Fin.castAdd}\\, m\\, j)\\bigr) = \\mathrm{Ioc}\\, i\\, j.$$$$
Lean4
@[simp]
theorem preimage_castAdd_Ioc_castAdd (m) (i j : Fin n) : castAdd m ⁻¹' Ioc (castAdd m i) (castAdd m j) = Ioc i j :=
rfl