English
For any c, IsBigOWith (‖c‖) l f' g' holds if IsBigOWith c l f' g'.
Русский
Для любого c: IsBigOWith (‖c‖) l f' g' следует из IsBigOWith c l f' g'.
LaTeX
$$$ IsBigOWith (\|c\|) l f' g' \leftarrow IsBigOWith c l f' g'. $$$
Lean4
theorem smul (h₁ : IsBigOWith c l k₁ k₂) (h₂ : IsBigOWith c' l f' g') :
IsBigOWith (c * c') l (fun x => k₁ x • f' x) fun x => k₂ x • g' x :=
by
simp only [IsBigOWith_def] at *
filter_upwards [h₁, h₂] with _ hx₁ hx₂
apply le_trans (norm_smul_le _ _)
convert mul_le_mul hx₁ hx₂ (norm_nonneg _) (le_trans (norm_nonneg _) hx₁) using 1
rw [norm_smul, mul_mul_mul_comm]