∀ {α : Type u_1} {γ : Type u_2} {mα : MeasurableSpace α} {mγ : MeasurableSpace γ}
  [hαγ : MeasurableSpace.CountableOrCountablyGenerated α γ] {κ η : ProbabilityTheory.Kernel α γ}
  [ProbabilityTheory.IsFiniteKernel κ] [ProbabilityTheory.IsFiniteKernel η] {a : α} {s : Set γ},
  MeasurableSet s → ∫⁻ (c : γ) in s, κ.rnDeriv η a c ∂η a ≤ (κ a) s