English
For x ∈ s in a subgroup class S, the norm in s equals the norm in E: ‖x‖ = ‖(x:E)‖.
Русский
Для x ∈ s в классе подгрупп S норма в s равна норме в E: ‖x‖ = ‖(x:E)‖.
LaTeX
$$$ ‖x‖ = ‖(x : E)‖ $$$
Lean4
/-- A subgroup of a seminormed group is also a seminormed group,
with the restriction of the norm. -/
@[to_additive /-- A subgroup of a seminormed additive group is also a seminormed additive group,
with the restriction of the norm. -/
]
instance (priority := 75) seminormedGroup : SeminormedGroup s :=
SeminormedGroup.induced _ _ (SubgroupClass.subtype s)