R : Type u_1
inst✝ : Semiring R
f : R[X]
a : ℕ
h : a ≠ natDegree f ∧ a ∈ support f
⊢ a < natDegree f
R : Type u_1
inst✝ : Semiring R
f : R[X]
a : ℕ
h : a ∈ support (eraseLead f)
⊢ a < natDegree f
rw [eraseLead_support, mem_erase] at h
no goals
R : Type u_1
inst✝ : Semiring R
f : R[X]
a : ℕ
h : a ≠ natDegree f ∧ a ∈ support f
⊢ a < natDegree f
exact (le_natDegree_of_mem_supp a h.2).lt_of_ne h.1