English
If x ≡ y mod I, then x^n ≡ y^n mod I for any natural n.
Русский
Если x ≡ y mod I, то x^n ≡ y^n mod I для любого натурального n.
LaTeX
$$$$ x \\equiv y\\ [SMOD\\ I] \\Rightarrow x^n \\equiv y^n\\ [SMOD\\ I]. $$$$
Lean4
@[gcongr]
theorem pow {I : Ideal A} {x y : A} (n : ℕ) (hxy : x ≡ y [SMOD I]) : x ^ n ≡ y ^ n [SMOD I] :=
by
simp only [SModEq.def, Ideal.Quotient.mk_eq_mk, map_pow] at hxy ⊢
rw [hxy]