exact AA.cancelR ‹(a₁ + c₂) + (b₂ + b₁) ≃ (c₁ + a₂) + (b₂ + b₁)›
ℕ : Type
inst✝ : Natural ℕ
a₁ a₂ b₁ b₂ c₁ c₂ : ℕ
x✝¹ : a₁ + b₂ ≃ b₁ + a₂
x✝ : b₁ + c₂ ≃ c₁ + b₂
this : a₁ + c₂ + (b₂ + b₁) ≃ c₁ + a₂ + (b₂ + b₁)
⊢ a₁ + c₂ ≃ c₁ + a₂
no goals