Exercise 5.3. Let G be a group and H, K be two subgroups of G. (1) Show that HK := {hk | h € H, k = K} is a disjoint union of some left cosets of K. (2) Let H, K be subgroups of G. Show that we have the following bijection (between coset spaces) K/(H^K) → HK/K defined by к(HK) → KK, Vк(HK) Є K/(H□K), where HK/K := {left cosets of K in HK}. (3) Suppose [G: H] and [G: K] are both finite. Prove or disprove that [G: HK] is finite.
Exercise 5.3. Let G be a group and H, K be two subgroups of G. (1) Show that HK := {hk | h € H, k = K} is a disjoint union of some left cosets of K. (2) Let H, K be subgroups of G. Show that we have the following bijection (between coset spaces) K/(H^K) → HK/K defined by к(HK) → KK, Vк(HK) Є K/(H□K), where HK/K := {left cosets of K in HK}. (3) Suppose [G: H] and [G: K] are both finite. Prove or disprove that [G: HK] is finite.
Algebra and Trigonometry (6th Edition)
6th Edition
ISBN:9780134463216
Author:Robert F. Blitzer
Publisher:Robert F. Blitzer
ChapterP: Prerequisites: Fundamental Concepts Of Algebra
Section: Chapter Questions
Problem 1MCCP: In Exercises 1-25, simplify the given expression or perform the indicated operation (and simplify,...
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![Exercise 5.3. Let G be a group and H, K be two subgroups of G.
(1) Show that HK := {hk | h € H, k = K} is a disjoint union of some left cosets of K.
(2) Let H, K be subgroups of G. Show that we have the following bijection (between coset
spaces)
K/(H^K) → HK/K defined by
к(HK) → KK, Vк(HK) Є K/(H□K),
where HK/K := {left cosets of K in HK}.
(3) Suppose [G: H] and [G: K] are both finite. Prove or disprove that [G: HK]
is finite.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Ff2e948f6-fd6f-485f-942e-c931230f8579%2Fdce70917-2947-4e80-9e24-609ac5985e81%2F6kirhwo_processed.jpeg&w=3840&q=75)
Transcribed Image Text:Exercise 5.3. Let G be a group and H, K be two subgroups of G.
(1) Show that HK := {hk | h € H, k = K} is a disjoint union of some left cosets of K.
(2) Let H, K be subgroups of G. Show that we have the following bijection (between coset
spaces)
K/(H^K) → HK/K defined by
к(HK) → KK, Vк(HK) Є K/(H□K),
where HK/K := {left cosets of K in HK}.
(3) Suppose [G: H] and [G: K] are both finite. Prove or disprove that [G: HK]
is finite.
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