English
Reiterating the NPow characterization of saturated subgroups.
Русский
Повторно характеризуем насыщенность подгрупп через NPow.
LaTeX
$$Saturated(H) ↔ ∀ (n : Nat) (g : G), g ^ n ∈ H → n = 0 ∨ g ∈ H$$
Lean4
/-- The center of a multiplication with unit `M` is the set of elements that commute with everything
in `M` -/
@[to_additive /-- The center of an addition with zero `M` is the set of elements that commute with everything in
`M` -/
]
def center : Submonoid M where
carrier := Set.center M
one_mem' := Set.one_mem_center
mul_mem' := Set.mul_mem_center