Problem 1E Problem 2E: Find Aut(Z). Problem 3E: Let R+ be the group of positive real numbers under multiplication.Show that the mapping (x)=x is an... Problem 4E: Show that U(8) is not isomorphic to U(10). Problem 5E: Show that U(8) is isomorphic to U(12). Problem 6E: Prove that isomorphism is an equivalence relation. That is, for anygroups G, H, and K... Problem 7E: Prove that S4 is not isomorphic to D12 . Problem 8E: Show that the mapping alog10a is an isomorphism from R+ undermultiplication to R under addition. Problem 9E: In the notation of Theorem 6.1, prove that Te is the identity andthat (Tg)1=Tg1 . Problem 10E: Given that is a isomorphism from a group G under addition to agroup G under addition, convert... Problem 11E: Let G be a group under multiplication, G be a group under additionand be an isomorphism from G to G... Problem 12E: Let G be a group. Prove that the mapping (g)=g1 for all g in Gis an automorphism if and only if G is... Problem 13E Problem 14E: Find two groups G and H such that GH , but Aut(G)Aut(H) . Problem 15E Problem 16E: Find Aut(Z6) . Problem 17E: If G is a group, prove that Aut(G) and Inn(G) are groups. (Thisexercise is referred to in this... Problem 18E: If a group G is isomorphic to H, prove that Aut(G) is isomorphic toAut(H). Problem 19E: Suppose belongs to Aut(Zn) and a is relatively prime to n.If (a)=b , determine a formula for (x) . Problem 20E: Let H be the subgroup of all rotations in Dn and let be an automorphismof Dn . Prove that (H)=H .... Problem 21E: Let H=S5(1)=1andK=S5(2)=2 . Provethat H is isomorphic to K. Is the same true if S5 is replaced by Sn... Problem 22E: Show that Z has infinitely many subgroups isomorphic to Z. Problem 23E Problem 24E: Let be an automorphism of a group G. Prove that H=xG(x)=x is a subgroup of G. Problem 25E Problem 26E: Suppose that :Z20Z20 is an automorphismand (5)=5 . Whatare the possibilities for (x) ? Problem 27E: Identify a group G that has subgroups isomorphic to Zn for all positiveintegers n. Problem 28E: Prove that the mapping from U(16) to itself given by xx3 is anautomorphism. Problem 29E: Let rU(n) . Prove that the mapping a: ZnZn defined by (s)=sr mod n for all s in Zn is an... Problem 30E: The group {[1a01]|aZ} is isomorphic to what familiar group? What if Z is replaced by R? Problem 31E: If and are isomorphisms from the cyclic group a to somegroup and (a)=(a) , prove that = . Problem 32E Problem 33E: Prove property 1 of Theorem 6.3. Theorem 6.3 Properties of Isomorphisms Acting on Groups Suppose... Problem 34E: Prove property 4 of Theorem 6.3. Theorem 6.3 Properties of Isomorphisms Acting on Groups Suppose... Problem 35E: Referring to Theorem 6.1, prove that Tg is indeed a permutation onthe set G. Problem 36E: Prove or disprove that U(20) and U(24) are isomorphic. Problem 37E: Show that the mapping (a+bi)=a=bi is an automorphism ofthe group of complex numbers under addition.... Problem 38E: Let G={a+b2a,barerational} and H={a2bba|a,barerational} .Show that G and H are isomorphic under... Problem 39E Problem 40E: Explain why S8 contains subgroups isomorphic to Z15 , U(16), and D8 . Problem 41E: Let C be the complex numbers and M={[abba]|a,bR} . Prove that C and M are isomorphic under addition... Problem 42E Problem 43E Problem 44E: Suppose that G is a finite Abelian group and G has no element oforder 2. Show that the mapping gg2... Problem 45E Problem 46E Problem 47E: Suppose that g and h induce the same inner automorphism of agroup G. Prove that h1gZ(G) . Problem 48E Problem 49E Problem 50E Problem 51E Problem 52E: Let G be a group. Complete the following statement: Inn(G)=1 if and only if _______________. Problem 53E: Suppose that G is an Abelian group and is an automorphism of G.Prove that H=xG(x)=x1 is a subgroup... Problem 54E: Let be an automorphismof D8 . What are the possibilities for (R45) ? Problem 55E: Let be an automorphism of C*, the group of nonzero complexnumbers under multiplcation. Determine... Problem 56E: Let G=0,2,4,6,...andH=0,3,6,9,... .Prove that G and H are isomorphic groups under addition by... Problem 57E: Give three examples of groups of order 120, no two of which areisomophic. Explain why they are not... Problem 58E: Let be an automorphism of D4 such that (H)=D . Find (V) . Problem 59E Problem 60E Problem 61E: Write the permutation corresponding to R90 in the left regular representationof D4 in cycle form. Problem 62E: Show that every automorphism of the rational numbers Q underaddition to itself has the form... Problem 63E: Prove that Q+ , the group of positive rational numbers under multiplication,is isomorphic to a... Problem 64E Problem 65E Problem 66E: Prove that Q*, the group of nonzero rational numbers under multiplication,is not isomorphic to Q,... Problem 67E: Give a group theoretic proof that Q under addition is not isomorphicto R+ under multiplication. format_list_bulleted