Theorem: ℤθ.my_mul_zero (Mordell4/CubicRing.lean)

State before:
a b c : ℤθ
⊢ mul a zero = zero
Tactic:
cases a
State after:
case mk
b c : ℤθ
f✝ g✝ h✝ : ℤ
⊢ mul { f := f✝, g := g✝, h := h✝ } zero = zero

State before:
case mk
b c : ℤθ
f✝ g✝ h✝ : ℤ
⊢ mul { f := f✝, g := g✝, h := h✝ } zero = zero
Tactic:
simp [mul, zero]
State after:
no goals