English
Under countability, κCond conditions imply κIsCondKernel via condKernelCountable.
Русский
При счетности условия κCond порождают κIsCondKernel через condKernelCountable.
LaTeX
$$$\\kappa^{\\text{Cond}}\\;\\Rightarrow\\; κIsCondKernel(condKernelCountable(κCond,h_{atom}))$$$
Lean4
instance instIsCondKernel [∀ a, IsMarkovKernel (κCond a)] (h_atom : ∀ x y, x ∈ measurableAtom y → κCond x = κCond y)
(κ : Kernel α (β × Ω)) [IsSFiniteKernel κ] [∀ a, (κ a).IsCondKernel (κCond a)] :
κ.IsCondKernel (condKernelCountable κCond h_atom) :=
by
constructor
ext a s hs
conv_rhs => rw [← (κ a).disintegrate (κCond a)]
simp_rw [compProd_apply hs, condKernelCountable_apply, Measure.compProd_apply hs]
congr