English
The centralizer of a subset s of G is the subgroup of G consisting of all elements that commute with every element of s.
Русский
Централизатор подмножества s в G — это подпгруппа, состоящая из элементов, commuting с каждым элементом s.
LaTeX
$$centralizer(s) = { g ∈ G ∣ ∀ h ∈ s, h g = g h }$$
Lean4
/-- The `centralizer` of `s` is the subgroup of `g : G` commuting with every `h : s`. -/
@[to_additive /-- The `centralizer` of `s` is the additive subgroup of `g : G` commuting with every `h : s`. -/
]
def centralizer (s : Set G) : Subgroup G :=
{ Submonoid.centralizer s with
carrier := Set.centralizer s
inv_mem' := Set.inv_mem_centralizer }