200 Groups The U-groups provide a convenient way to illustrate the preceding ideas and to clarify the distinction between internal and external direct products. It follows directly from Theorem 8.3, its corollary, and Theorem 9.6 that if m= nn2 where gcd(n, n) = 1 for i # j, then XU(m) (m) X U(m) X m/n U(m) = U U(n) U(n) mln minz U(n). Let us return to the examples given following Theorem 8.3 U15(105) X U,(105) U(105) U(15 7) = {1, 16, 31, 46, 61, 76 X {1, 8, 22, 29, 43, 64, 71, 92 U(7) U(15), U,(105) X U21 (105) U(105) U(5 21) = {1, 11, 16, 26, 31, 41, 46, 61, 71, 76, 86, 101) X {1, 22, 43, 64 U(21) U(5), U(3 5 7) = {1, 71} X {1, 22, 43, 64} X {1, 16, 31, 46, 61, 76} 2U(3 ) U(5) U(7). U5(105) X U2 (105) X U5(105) U(105) Exercises The heart of mathematics is its problems. Paul Halmos 1. Let H = {(1), (12)}. Is H normal in S,? 2. Prove that A, is normal in S п' n 3. In D, let K where x E K. Write DR, in the form xD, where x E K. Write RV in the form Vx, where x E K {Ro, R90, R180 R270. Write HR9 in the form xH = , 270 4. Write (12)(13)(14) in the form a(12), where a E A. Write (1234) (12)(23), in the form a(1234), where a E A. 5. Show that if G is the internal direct product of H, H2, ., H and i #j with 1 s in, 1 sjsn, then H, n H, {e}. (This exercise is referred to in this chapter.) a a, b, d e R, ad 0.Is Ha normal sub- 6. Let H = group of GL(2, R)? 7. Let G GL(2, R) and let K be a subgroup of R*. Prove that H = (A EGI det A E K} is a normal subgroup of G. 8. Viewing (3) and (12) as subgroups of Z, prove that (3)(12) is iso- morphic to Z. Similarly, prove that (8)/(48) is isomorphic to 2 Generalize to arbitrary integers k and n.

Elements Of Modern Algebra
8th Edition
ISBN:9781285463230
Author:Gilbert, Linda, Jimmie
Publisher:Gilbert, Linda, Jimmie
Chapter4: More On Groups
Section4.7: Direct Sums (optional)
Problem 22E
icon
Related questions
Topic Video
Question

8. 

200
Groups
The U-groups provide a convenient way to illustrate the preceding
ideas and to clarify the distinction between internal and external direct
products. It follows directly from Theorem 8.3, its corollary, and
Theorem 9.6 that if m= nn2
where gcd(n, n) =
1 for i # j, then
XU(m)
(m) X U(m) X
m/n
U(m) = U
U(n) U(n)
mln
minz
U(n).
Let us return to the examples given following Theorem 8.3
U15(105) X U,(105)
U(105)
U(15 7)
= {1, 16, 31, 46, 61, 76 X {1, 8, 22, 29, 43, 64, 71, 92
U(7) U(15),
U,(105) X U21 (105)
U(105)
U(5 21)
= {1, 11, 16, 26, 31, 41, 46, 61, 71, 76, 86, 101)
X {1, 22, 43, 64 U(21) U(5),
U(3 5 7)
= {1, 71} X {1, 22, 43, 64} X {1, 16, 31, 46, 61, 76}
2U(3 ) U(5) U(7).
U5(105) X U2 (105) X U5(105)
U(105)
Exercises
The heart of mathematics is its problems.
Paul Halmos
1. Let H = {(1), (12)}. Is H normal in S,?
2. Prove that A, is normal in S
п'
n
3. In D, let K
where x E K. Write DR, in the form xD, where x E K. Write RV
in the form Vx, where x E K
{Ro, R90, R180 R270. Write HR9 in the form xH
=
,
270
4. Write (12)(13)(14) in the form a(12), where a E A. Write (1234)
(12)(23), in the form a(1234), where a E A.
5. Show that if G is the internal direct product of H, H2, ., H and
i #j with 1 s in, 1 sjsn, then H, n H, {e}. (This exercise
is referred to in this chapter.)
a
a, b, d e R, ad 0.Is Ha normal sub-
6. Let H =
group of GL(2, R)?
7. Let G GL(2, R) and let K be a subgroup of R*. Prove that H =
(A EGI det A E K} is a normal subgroup of G.
8. Viewing (3) and (12) as subgroups of Z, prove that (3)(12) is iso-
morphic to Z. Similarly, prove that (8)/(48) is isomorphic to 2
Generalize to arbitrary integers k and n.
Transcribed Image Text:200 Groups The U-groups provide a convenient way to illustrate the preceding ideas and to clarify the distinction between internal and external direct products. It follows directly from Theorem 8.3, its corollary, and Theorem 9.6 that if m= nn2 where gcd(n, n) = 1 for i # j, then XU(m) (m) X U(m) X m/n U(m) = U U(n) U(n) mln minz U(n). Let us return to the examples given following Theorem 8.3 U15(105) X U,(105) U(105) U(15 7) = {1, 16, 31, 46, 61, 76 X {1, 8, 22, 29, 43, 64, 71, 92 U(7) U(15), U,(105) X U21 (105) U(105) U(5 21) = {1, 11, 16, 26, 31, 41, 46, 61, 71, 76, 86, 101) X {1, 22, 43, 64 U(21) U(5), U(3 5 7) = {1, 71} X {1, 22, 43, 64} X {1, 16, 31, 46, 61, 76} 2U(3 ) U(5) U(7). U5(105) X U2 (105) X U5(105) U(105) Exercises The heart of mathematics is its problems. Paul Halmos 1. Let H = {(1), (12)}. Is H normal in S,? 2. Prove that A, is normal in S п' n 3. In D, let K where x E K. Write DR, in the form xD, where x E K. Write RV in the form Vx, where x E K {Ro, R90, R180 R270. Write HR9 in the form xH = , 270 4. Write (12)(13)(14) in the form a(12), where a E A. Write (1234) (12)(23), in the form a(1234), where a E A. 5. Show that if G is the internal direct product of H, H2, ., H and i #j with 1 s in, 1 sjsn, then H, n H, {e}. (This exercise is referred to in this chapter.) a a, b, d e R, ad 0.Is Ha normal sub- 6. Let H = group of GL(2, R)? 7. Let G GL(2, R) and let K be a subgroup of R*. Prove that H = (A EGI det A E K} is a normal subgroup of G. 8. Viewing (3) and (12) as subgroups of Z, prove that (3)(12) is iso- morphic to Z. Similarly, prove that (8)/(48) is isomorphic to 2 Generalize to arbitrary integers k and n.
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 4 steps with 3 images

Blurred answer
Knowledge Booster
Discrete Probability Distributions
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, advanced-math and related others by exploring similar questions and additional content below.
Recommended textbooks for you
Elements Of Modern Algebra
Elements Of Modern Algebra
Algebra
ISBN:
9781285463230
Author:
Gilbert, Linda, Jimmie
Publisher:
Cengage Learning,
Linear Algebra: A Modern Introduction
Linear Algebra: A Modern Introduction
Algebra
ISBN:
9781285463247
Author:
David Poole
Publisher:
Cengage Learning
Elementary Linear Algebra (MindTap Course List)
Elementary Linear Algebra (MindTap Course List)
Algebra
ISBN:
9781305658004
Author:
Ron Larson
Publisher:
Cengage Learning