Show Commutativity of Group with All Elements of Order 2 & Consider Zn

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Discussion Overview

The discussion revolves around proving that a group G, where every non-identity element has order two, is commutative. Additionally, the participants explore properties of the group Zn, specifically regarding generators and the cyclic nature of its subgroups.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant requests assistance in proving that G is commutative under the condition that every non-identity element has order two.
  • Another participant questions the meaning of commutativity and seeks possible methods to demonstrate it.
  • Some participants suggest using a multiplication table to show commutativity, while others propose starting with the implication that if k and n are relatively prime, then k generates Zn.
  • There is a mention of wanting to explore the order of k in relation to the greatest common divisor of k and n.
  • One participant emphasizes the need to explicitly demonstrate the definition of commutativity in the given case.

Areas of Agreement / Disagreement

Participants express varying approaches to proving commutativity and the properties of Zn, indicating that multiple competing views remain on how to tackle the problems presented.

Contextual Notes

Participants have not yet resolved the mathematical steps required to show commutativity or the implications regarding generators in Zn.

Who May Find This Useful

This discussion may be useful for those studying group theory, particularly in understanding properties of groups with specific element orders and the structure of cyclic groups.

halvizo1031
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I need help here: Suppose that G is a group in which every non-identity element has order two. Show that G is commutative.


Also, Consider Zn = {0,1,...,n-1}
a. show that an element k is a generator of Zn if and only if k and n are relatively prime.

b. Is every subgroup of Zn cyclic? If so, give a proof. If not, provide an example.
 
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What does it mean that G is commutative?
What possible ways to prove commutativity do you know of?

For the second one, I suggest starting with the "<==" implication (i.e. assume that k and n are relatively prime and show that k generates Zn.
 
CompuChip said:
What does it mean that G is commutative?
What possible ways to prove commutativity do you know of?

For the second one, I suggest starting with the "<==" implication (i.e. assume that k and n are relatively prime and show that k generates Zn.



for the first one, we can show commutativity with a multiplication table. How else?

for the second one, i want to start with ==> and say that the order of k is n/(m,n). but how can i show it?
 
OK let's take them one at a time.

The definition of commutativity is that xy = yx for any two elements x and y.
Can you explicitly show this in the case given?
 

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