∀ {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} {κ : ProbabilityTheory.Kernel α β}
  (η : ProbabilityTheory.Kernel γ δ), ¬ProbabilityTheory.IsSFiniteKernel κ → κ.parallelComp η = 0