English
The coefficient of the lifted subring polynomial equals the original coefficient, after identifying it with the subring.
Русский
Коэффициент подкольцевого полинома равен исходному коэффициенту после соответствующего преобразования.
LaTeX
$$$\\uparrow\\mathrm{coeff}((\\mathrm{toSubring}\\ p\\ T\\ hp)\\,n) = \\mathrm{coeff}\\ p\\ n$$$
Lean4
@[simp]
theorem coeff_toSubring {n : ℕ} : ↑(coeff (toSubring p T hp) n) = coeff p n := by
classical
simp only [toSubring, coeff_monomial, finset_sum_coeff, mem_support_iff, Finset.sum_ite_eq', Ne, ite_not]
split_ifs with h
· rw [h]
rfl
· rfl