induction' n with n ih
case intro
a b n : ℕ
inst✝ : NeZero (Nat.succ n)
⊢ ∃ I, feasible (Nat.succ n) I ∧ mem a b I
case intro.zero
a b n : ℕ
inst✝ : NeZero (Nat.succ n)
⊢ ∃ I, feasible (Nat.succ Nat.zero) I ∧ mem a b I

case intro.succ
a b n✝ : ℕ
inst✝ : NeZero (Nat.succ n✝)
n : ℕ
ih : ∃ I, feasible (Nat.succ n) I ∧ mem a b I
⊢ ∃ I, feasible (Nat.succ (Nat.succ n)) I ∧ mem a b I