English
The product type β × γ carries a natural NormSMulClass α; the smul is defined componentwise with the product norm.
Русский
Произведение β × γ имеет естественную NormSMulClass α; умножение выполняется по компонентам с нормой на произведении.
LaTeX
$$$NormSMulClass\\;α\\;\\left(β \\times γ\\right)$$$
Lean4
instance instNormSMulClass {γ : Type*} [SeminormedAddGroup γ] [SMul α γ] [NormSMulClass α γ] : NormSMulClass α (β × γ)
where
norm_smul := fun r ⟨v₁, v₂⟩ ↦ by
simp only [smul_def, ← coe_nnnorm, nnnorm_def, nnnorm_smul r, ← NNReal.coe_mul, NNReal.mul_sup]