English
For any p, the membership of an index i in the support of optionEquivLeft(R,S1)(p) matches the membership of i in the degree structure of p.
Русский
Для любого p верно равенство членства i в опорe optionEquivLeft(p) и членство i в структуре степеней p.
LaTeX
$$$\\operatorname{natDegree}(((\\operatorname{optionEquivLeft} R S_1\\;p).\\coeff i)) = \\text{…}$$$
Lean4
theorem support_coeff_finSuccEquiv {f : MvPolynomial (Fin (n + 1)) R} {i : ℕ} {m : Fin n →₀ ℕ} :
m ∈ ((finSuccEquiv R n f).coeff i).support ↔ m.cons i ∈ f.support :=
by
apply Iff.intro
· intro h
simpa [← finSuccEquiv_coeff_coeff] using h
· intro h
simpa [mem_support_iff, ← finSuccEquiv_coeff_coeff m f i] using h