apply Finset.sup_le
case mpr.h
R : Type u_1
ι : Type u_2
inst✝ : CommSemiring R
i : ι
p : MvPolynomial ι R
h : ∀ j ∈ p.support, j i = 0
⊢ (p.support.sup fun m => m i) ≤ 0
case mpr.h.a
R : Type u_1
ι : Type u_2
inst✝ : CommSemiring R
i : ι
p : MvPolynomial ι R
h : ∀ j ∈ p.support, j i = 0
⊢ ∀ b ∈ p.support, b i ≤ 0