English
A subalgebra of a seminormed commutative ring is itself a seminormed commutative ring under the restricted norm.
Русский
Подалгебра семинормированного кольца остаётся семинарномерным коммутативным кольцом при ограничении нормы.
LaTeX
$$$\text{If } s \le E \text{ is a subalgebra, then } s \text{ is a SeminormedCommRing with restricted norm.}$$$
Lean4
/-- A subalgebra of a seminormed commutative ring is also a seminormed commutative ring, with the
restriction of the norm. -/
instance seminormedCommRing {𝕜 : Type*} [CommRing 𝕜] {E : Type*} [SeminormedCommRing E] [Algebra 𝕜 E]
(s : Subalgebra 𝕜 E) : SeminormedCommRing s :=
{ s.seminormedRing, s.toCommRing with }