Can a Group of Order 20 with Elements of Order 4 Be Cyclic?

  • Context: Graduate 
  • Thread starter Thread starter DeldotB
  • Start date Start date
  • Tags Tags
    Cyclic Group
Click For Summary

Discussion Overview

The discussion centers on whether a group of order 20 that contains elements of order 4 can be cyclic. Participants explore the implications of having multiple elements of order 4 and the conditions under which a group can be cyclic, with a focus on abstract algebra concepts.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant questions if a group of order 20 with three elements of order 4 can be cyclic, and asks how the situation changes with two elements.
  • Another participant states that if the group is cyclic, it must have a generator element, and discusses the implications of having elements of order 4 in relation to the powers of the generator.
  • A participant inquires whether the powers of elements need to divide the order of the group (20).
  • Another participant clarifies that while the condition of powers dividing the group order is sufficient, it is not necessary, and emphasizes the structure of cyclic groups of order 20.

Areas of Agreement / Disagreement

Participants express differing views on the implications of having elements of order 4 in a group of order 20, and the discussion remains unresolved regarding whether such a group can be cyclic.

Contextual Notes

Participants have not reached a consensus on the conditions under which a group of order 20 with elements of order 4 can be cyclic, and there are unresolved assumptions regarding the structure of cyclic groups.

DeldotB
Messages
117
Reaction score
8
Hello all!

If I have a group of order 20 that has three elements of order 4, can this group be cyclic? What if it has two elements? I am new to abstract algebra, so please keep that in mind!

Thanks!
 
Physics news on Phys.org
If it's cyclic then it has a generator element g such that ##g^{20}=1## and ##1,g,g^2,...,g^{19}## are all different.

Let the three elements of order 4 be a, b and c.

What can we deduce about what powers of g each of those elements could be?
 
Do the powers need to divide 20?
 
That's a sufficient, but not a necessary condition.

Think about the* cyclic group of order 20: {1,##g,g^2,...,g^{19}##}. Express the fourth power of each of its elements as ##g^m## where ##m<20##.

*Note the use of 'the' rather than 'a'. All cyclic groups of order 'n' are isomorphic.
 

Similar threads

  • · Replies 7 ·
Replies
7
Views
4K
  • · Replies 7 ·
Replies
7
Views
5K
Replies
3
Views
3K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 17 ·
Replies
17
Views
10K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 26 ·
Replies
26
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 13 ·
Replies
13
Views
4K