English
The product of finitely many normed algebras is a normed algebra, with the sup norm.
Русский
Произведение конечного числа нормированных алгебр является нормированной алгеброй с суп-нормой.
LaTeX
$$$\\mathrm{NormedAlgebra}_{\\mathbb{K}}(\\prod_{i=1}^n E_i)$$$
Lean4
/-- The product of two normed algebras is a normed algebra, with the sup norm. -/
instance normedAlgebra {E F : Type*} [SeminormedRing E] [SeminormedRing F] [NormedAlgebra 𝕜 E] [NormedAlgebra 𝕜 F] :
NormedAlgebra 𝕜 (E × F) :=
{ Prod.normedSpace, Prod.algebra 𝕜 E F with }