Theorem: MyGroup.mul_eq_one_iff_eq_inv (IIScExperiments/Solutions/GroupTheorySolutions.lean)

State before:
G : Type
inst✝ : MyGroup G
a b c : G
⊢ a⁻¹ = b → a * b = 1
Tactic:
rintro rfl
State after:
G : Type
inst✝ : MyGroup G
a c : G
⊢ a * a⁻¹ = 1

State before:
G : Type
inst✝ : MyGroup G
a c : G
⊢ a * a⁻¹ = 1
Tactic:
simp
State after:
no goals