∀ {R₁ : Type u_1} {R₂ : Type u_2} {R₃ : Type u_3} [inst : Semiring R₁] [inst_1 : Semiring R₂] [inst_2 : Semiring R₃]
  {σ₁₂ : R₁ →+* R₂} {σ₂₃ : R₂ →+* R₃} {σ₁₃ : R₁ →+* R₃} [RingHomCompTriple σ₁₂ σ₂₃ σ₁₃] [RingHomSurjective σ₁₂]
  [RingHomSurjective σ₂₃], RingHomSurjective σ₁₃