English
If f is Theta relative to g, then f composed with fst is Theta relative to g composed with fst.
Русский
Если f =Θ[l] g, то f ∘ fst = Θ[l×ˢ] g ∘ fst.
LaTeX
$$$\forall f,g:\; f =Θ[l] g \Rightarrow (f \circ Prod.fst) =Θ[l' \timesˢ l] (g \circ Prod.fst)$$$
Lean4
/-- A real function into a finite-dimensional real vector space with bounded variation on a set
is differentiable almost everywhere in this set. -/
theorem ae_differentiableWithinAt {f : ℝ → V} {s : Set ℝ} (h : LocallyBoundedVariationOn f s) (hs : MeasurableSet s) :
∀ᵐ x ∂volume.restrict s, DifferentiableWithinAt ℝ f s x :=
by
rw [ae_restrict_iff' hs]
exact h.ae_differentiableWithinAt_of_mem