Let G be a group. The center of
G is the set
Z(G) = {g∈G
|gh = hg
∀h∈G}. For
a∈G, the centralizer of
a is the set
C(a)
={g∈G |ga
=ag }
(a)Prove that Z(G) is an
abelian subgroup of G.
(b)Compute the center of D4.
(c)Compute the center of the group G of the shuffles of three
objects x1,x2,x3.
○n: no shuffling occurred
○s12: swap the first and second items
○s13: swap the first and third items
○s23:...