English
If f and g are interval-integrable on [a,b], then their sum is interval-integrable on [a,b].
Русский
Если f и g интервал-интегрируемы на [a,b], то их сумма интегрируема на [a,b].
LaTeX
$$$\operatorname{IntervalIntegrable}(f,\mu,a,b) \land \operatorname{IntervalIntegrable}(g,\mu,a,b) \Rightarrow \operatorname{IntervalIntegrable}(x \mapsto f(x)+g(x),\mu,a,b)$$$
Lean4
@[simp]
theorem add [ContinuousAdd ε] (hf : IntervalIntegrable f μ a b) (hg : IntervalIntegrable g μ a b) :
IntervalIntegrable (fun x => f x + g x) μ a b :=
⟨hf.1.add hg.1, hf.2.add hg.2⟩