exact  ih h
R : Type u_2
inst✝² : Ring R
inst✝¹ : DecidableEq R
X : Type u_1
inst✝ : DecidableEq X
norm : X → ℕ
crds : X → R
head : X
tail : List X
ih : maxNormSuccOnSupp norm crds tail > 0 → ∃ x, crds x ≠ 0 ∧ maxNormSuccOnSupp norm crds tail = norm x + 1
c : crds head = 0
h : maxNormSuccOnSupp norm crds tail > 0
⊢ ∃ x, ¬crds x = 0 ∧ maxNormSuccOnSupp norm crds tail = norm x + 1
no goals