Solving Group Problems: |g| = 20 in G and Subgroup H = <x,y>

  • Thread starter Thread starter hsong9
  • Start date Start date
  • Tags Tags
    Group Subgroup
Click For Summary

Homework Help Overview

The discussion revolves around group theory, specifically focusing on the properties of elements in a group G with order |g| = 20 and the computation of orders for various powers of g. Participants are also exploring the formation of subgroups H generated by specific elements.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants attempt to compute the orders of g raised to different powers and discuss the implications of these computations. There are questions regarding the subgroup structures for different group types, including cyclic groups and symmetric groups. Some participants express uncertainty about specific calculations and the meaning of group operations.

Discussion Status

The discussion is active, with participants sharing their attempts and reasoning. Some guidance has been provided regarding the subgroup generated by elements in cyclic groups, and there is a recognition of the need to compute specific group operations in concrete examples. Multiple interpretations of subgroup formation are being explored.

Contextual Notes

Participants are working within the constraints of group theory and are encouraged to compute orders and subgroup structures based on given elements. There is an acknowledgment of the complexity involved in different group types and the necessity of understanding group operations.

hsong9
Messages
71
Reaction score
1

Homework Statement


A. Let |g| = 20 in a group G. Compute
|g^2|, |g^8|,|g^5|, |g^3|

B. In each case find the subgroup H = <x,y> of G.
a) G = <a> is cyclic, x = a^m, y = a^k, gcd(m,k)=d
b) G=S_3, x=(1 2), y=(2 3)
c) G = <a> * <b>, |a| = 4, |b| = 6, x = (a^2, b), y = (a,b^3)

The Attempt at a Solution


A. I know |g^2| = 20/2 = 10 and |g^5| = 20/5 = 4
But |g^8|, |g^3| don't know..

B. a)H=<a^d> , right?
but
I don't know how to solve b) and c)
Thanks!
 
Physics news on Phys.org
hsong9 said:

The Attempt at a Solution


A. I know |g^2| = 20/2 = 10 and |g^5| = 20/5 = 4
But |g^8|, |g^3| don't know..

Don't forget that if [itex]g^{20}=e[/itex] then [itex]g^{40}=e[/itex] also.

B. a)H=<a^d> , right?

Yes.

but
I don't know how to solve b) and c)
Thanks!

b should be easy, because you've got a concrete group to play with. Just get in there and start computing. As for c, what does <a>*<b> mean?
 
The least common multiple of 20 and 8 is 2*4*5= 40. [itex](g^8)^5= (g^20)^2= e[/itex].

The least common multiple of 3 and 20 is 60. [itex](g^3)^20= (g^20)^3= e[/itex].
 
so.. for b) is H=(1 2) * (2 3) = (1 2 3)..?
 
Yes, that's right.
 

Similar threads

Replies
2
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
Replies
5
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
Replies
6
Views
1K
  • · Replies 5 ·
Replies
5
Views
2K