∀ {α : Type u_1} {β : Type u_2} {mα : MeasurableSpace α} {mβ : MeasurableSpace β} {μ ν : MeasureTheory.Measure α}
  {κ η : ProbabilityTheory.Kernel α β} [MeasureTheory.SFinite ν] [ProbabilityTheory.IsSFiniteKernel η],
  μ.AbsolutelyContinuous ν →
    (μ.compProd κ).AbsolutelyContinuous (μ.compProd η) → (μ.compProd κ).AbsolutelyContinuous (ν.compProd η)