English
For any integer n, the composition of the quotient by span{n} with the quotient equivalence to ZMod n.natAbs equals the canonical cast to ZMod n.natAbs.
Русский
Для целого n композиция деления по span{n} с эквививкой к ZMod n.natAbs равна каноническому отображению в ZMod n.natAbs.
LaTeX
$$$$ (Int.quotientSpanEquivZMod n : _ →+* _).comp (Ideal.Quotient.mk (Ideal.span { (n : \\mathbb{Z}) })) = Int.castRingHom (\\mathbb{Z} / n.\\natAbs \\mathbb{Z}) $$$$
Lean4
@[simp]
theorem quotientSpanEquivZMod_comp_Quotient_mk (n : ℤ) :
(Int.quotientSpanEquivZMod n : _ →+* _).comp (Ideal.Quotient.mk (Ideal.span {(n : ℤ)})) =
Int.castRingHom (ZMod n.natAbs) :=
rfl