∀ {α : Type u_1} {β : Type u_2} {mα : MeasurableSpace α} {mβ : MeasurableSpace β} {κ ν : ProbabilityTheory.Kernel α β}
  [hν : ProbabilityTheory.IsFiniteKernel ν], κ ≤ ν → ProbabilityTheory.IsFiniteKernel κ