{α : Type u_1} →
  {β : Type u_2} →
    {γ : Type u_3} →
      {δ : Type u_4} →
        {mα : MeasurableSpace α} →
          {mβ : MeasurableSpace β} →
            {mγ : MeasurableSpace γ} →
              {mδ : MeasurableSpace δ} →
                ProbabilityTheory.Kernel α β → ProbabilityTheory.Kernel γ δ → ProbabilityTheory.Kernel (α × γ) (β × δ)