Let G be a group and let N ≤ G be a normal subgroup.
(i) Define the factor group G/N and show that G/N is a
group.
(ii) Let G = S4, N = K4 = h(1, 2)(3, 4),(1, 3)(2, 4)i ≤ S4. Show
that N is a normal subgroup of G and write out the set of cosets
G/N.
4.- Show the solution:
a.- Let G be a group, H a subgroup of G and a∈G. Prove that the
coset aH has the same number of elements as H.
b.- Prove that if G is a finite group and a∈G, then |a| divides
|G|. Moreover, if |G| is prime then G is cyclic.
c.- Prove that every group is isomorphic to a group of
permutations.
SUBJECT: Abstract Algebra
(18,19,20)
1) What permutation group is pentagon D5 a subgroup of ?why?
2) What is a generating set of pentagon D5? Why? Is it a minimal
generating set?Why or why not?
3) What is not a generating set of pentagon D5? Why?
1. Let N be a normal subgroup of G and let H be any subgroup
of G. Let HN = {hn|h ∈ H,n ∈
N}. Show that HN is a subgroup of G, and is the smallest
subgroup containing both N and H.
Let N be a normal subgroup of the group G.
(a) Show that every inner automorphism of G defines an
automorphism of N.
(b) Give an example of a group G with a normal subgroup N and an
automorphism of N that is not defined by an inner automorphism of
G
Let (G,+) be an abelian group and U a subgroup of G. Prove that
G is the direct product of U and V (where V a subgroup of G) if
only if there is a homomorphism f : G → U with f|U =
IdU
Let
G be a finite group and H a subgroup of G. Let a be an element of G
and aH = {ah : h is an element of H} be a left coset of H. If b is
an element of G as well and the intersection of aH bH is non-empty
then aH and bH contain the same number of elements in G. Thus
conclude that the number of elements in H, o(H), divides the number
of elements...
G
is a group and H is a normal subgroup of G. List the elements of
G/H and then write the table of G/H.
1. G=Z10, H= {0,5}. (Explain why G/H is congruent to Z5)
2. G=S4 and H= {e, (12)(34), (13)(24), (14)(23)