English
Let I be a two-sided ideal in a semiring R. For every pair of natural numbers m and n, the (m+n)‑th power of I equals the product of its m‑th and n‑th powers: I^{m+n} = I^m I^n.
Русский
Пусть I — двусторонний идеал полуг ringsajo R. Для любых натуральных чисел m и n выполняется I^{m+n} = I^m I^n.
LaTeX
$$$ \\forall R [\\text{Semiring } R], \\forall I : \\mathrm{Ideal}\\, R,[I \\text{ IsTwoSided}] \\forall m,n \\in \\mathbb{N}, I^{m+n} = I^{m} I^{n}$$$
Lean4
protected theorem pow_add : I ^ (m + n) = I ^ m * I ^ n :=
by
obtain rfl | h := eq_or_ne n 0
· rw [add_zero, Submodule.pow_zero, IsTwoSided.mul_one]
· exact Submodule.pow_add _ h