English
Dual to Left Sum, κ ⊗ η equals the sum over i of κ ⊗ seq η i when η is indexed by i.
Русский
Дуал к левому разложению: κ ⊗ η = ∑_i κ ⊗ seq η i, когда η индексировано по i.
LaTeX
$$$$ κ \\otimes_{\\kern-0.2em} η \\\\ = \\\\ \\mathrm{Kernel.sum}\\ i \\; (κ \\otimes_{\\kern-0.2em} (\\mathrm{seq}\\, η\\, i)). $$$$
Lean4
theorem compProd_add_right (μ : Kernel α β) (κ η : Kernel (α × β) γ) [IsSFiniteKernel κ] [IsSFiniteKernel η] :
μ ⊗ₖ (κ + η) = μ ⊗ₖ κ + μ ⊗ₖ η := by
by_cases hμ : IsSFiniteKernel μ
swap; · simp [hμ]
ext a s hs
simp only [compProd_apply hs, coe_add, Pi.add_apply, Measure.coe_add]
rw [lintegral_add_left]
exact measurable_kernel_prodMk_left' hs a