Theorem: MyGroup.mul_inv_rev (LeanInRome/S2_Basics/S02_Proving_Identities_in_Algebraic_Structures.lean)

State before:
G : Type u_1
inst✝ : Group G
a b : G
⊢ (a * b)⁻¹ = b⁻¹ * a⁻¹
Tactic:
sorry
State after:
no goals