Theorem: Section5sheet2Solutions.WeakGroup.mul_inv_self (FormalisingMathematics2024/Solutions/Section05groups/Sheet2.lean)

State before:
G : Type
inst✝ : WeakGroup G
a✝ b c a : G
⊢ a * a⁻¹ = 1
Tactic:
apply mul_eq_of_eq_inv_mul
State after:
case h
G : Type
inst✝ : WeakGroup G
a✝ b c a : G
⊢ a⁻¹ = a⁻¹ * 1

State before:
case h
G : Type
inst✝ : WeakGroup G
a✝ b c a : G
⊢ a⁻¹ = a⁻¹ * 1
Tactic:
rw [mul_one]
State after:
no goals