Theorem: Tutorial.mul_inv_self (Solution/Advanced/Algebra/Lecture1.lean)

State before:
A : Type ?u.9053
G : Type
inst✝¹ : Ring A
inst✝ : Group G
a : G
⊢ a * a⁻¹ = 1
Tactic:
apply mul_left_cancel (a := a⁻¹)
State after:
A : Type ?u.9053
G : Type
inst✝¹ : Ring A
inst✝ : Group G
a : G
⊢ a⁻¹ * (a * a⁻¹) = a⁻¹ * 1

State before:
A : Type ?u.9053
G : Type
inst✝¹ : Ring A
inst✝ : Group G
a : G
⊢ a⁻¹ * (a * a⁻¹) = a⁻¹ * 1
Tactic:
simp
State after:
no goals