Theorem: Tutorial.inv_one (Tutorial/Advanced/Algebra/Lecture1.lean)

State before:
A : Type ?u.3411
G : Type
inst✝¹ : Ring A
inst✝ : Group G
⊢ 1⁻¹ = 1
Tactic:
apply inv_eq_of_mul_eq_one_left
State after:
case a
A : Type ?u.3411
G : Type
inst✝¹ : Ring A
inst✝ : Group G
⊢ 1 * 1 = 1

State before:
case a
A : Type ?u.3411
G : Type
inst✝¹ : Ring A
inst✝ : Group G
⊢ 1 * 1 = 1
Tactic:
sorry
State after:
no goals