If G is a group, show that the set of automorphisms of G and the set...

If G is a group, show that the set of automorphisms of G and the set of inner automorphisms of G are both groups.

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Colby Messinger answered 3 years ago

An automorphism of a group G is an isomorphism from G to G. The set of...

An automorphism of a group G is an isomorphism from G to G. The set of all automorphisms of G forms a group Aut(G), where the group multiplication is the composition of automorphisms. The group Aut(G) is called the automorphism group of group G. (a) Show that Aut(Z) ≃ Z2. (Hint: consider generators of Z.) (b) Show that Aut(Z2 × Z2) ≃ S3. (c) Prove that if Aut(G) is cyclic then G is abelian.

Let G be a group. The center of G is the set Z(G) = {g∈G |gh...

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:...

Let G be a group acting on a set S, and let H be a group...

Let G be a group acting on a set S, and let H be a group acting on a set T. The product group G × H acts on the disjoint union S ∪ T as follows. For all g ∈ G, h ∈ H, s ∈ S and t ∈ T, (g, h) · s = g · s, (g, h) · t = h · t. (a) Consider the groups G = C4, H = C5, each acting...

Let G be a group. Consider the set G with a new operation ∗ given by...

Let G be a group. Consider the set G with a new operation ∗ given by a ∗ b = ba. Show that (G, ∗) is a group isomorphic to the original group G. Give an explicit isomorphism.

4.- Show the solution: a.- Let G be a group, H a subgroup of G and...

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) Let G be a group and H, K be subgroups of G. (a) Show that...

(1) Let G be a group and H, K be subgroups of G. (a) Show that if H is a normal subgroup, then HK = {xy|x ? H, y ? K} is a subgroup of G. (b) Show that if H and K are both normal subgroups, then HK is also a normal subgroup. (c) Give an example of subgroups H and K such that HK is not a subgroup of G.

Suppose that a group G acts on its power set P(G) by conjugation. a) If H≤G,...

Suppose that a group G acts on its power set P(G) by conjugation. a) If H≤G, prove that the normalizer of N(H) is the largest subgroup K of G such that HEK. In particular, if G is finite show that |H| divides |N(H)|. b) Show that H≤G⇐⇒every element B∈OH is a subgroup of G with B∼=H. c) Prove that HEG⇐⇒|OH|= 1.

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If G is a group, show that the set of automorphisms of G and the set...

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