English
The identity kernel on a product equals the product of deterministic fst and snd projections: id_prod_eq expresses @Kernel.id(α × β) as deterministic fst ×κ deterministic snd.
Русский
Ядро идентичности на произведение равно произведению детерминированных проекций fst и snd.
LaTeX
$$$\\displaystyle @Kernel.id (\\alpha \\times \\beta) = (\\mathrm{deterministic} \\mathrm{Prod.fst} \\; \\mathrm{measurable\_fst}) \\times_K (\\mathrm{deterministic} \\mathrm{Prod.snd} \\; \\mathrm{measurable\_snd})$$$
Lean4
theorem id_prod_eq :
@Kernel.id (α × β) inferInstance =
(deterministic Prod.fst measurable_fst) ×ₖ (deterministic Prod.snd measurable_snd) :=
by
rw [deterministic_prod_deterministic]
rfl