English
The center of a magma is the set of all elements that commute with every element; equivalently IsMulCentral z.
Русский
Центр магмы — множества элементов, которые commute с каждым элементом; то есть IsMulCentral z.
LaTeX
$$$\\operatorname{center}(M) = \\{ z \\in M \\mid \\forall x \\in M, x z = z x \\}$$$
Lean4
/-- The center of a magma. -/
@[to_additive addCenter /-- The center of an additive magma. -/
]
def center : Set M :=
{z | IsMulCentral z}