Group of Order 4: Cyclic & C2xC2

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Discussion Overview

The discussion revolves around identifying a condition that characterizes a group of order 4, specifically distinguishing between the cyclic group and the direct product of two cyclic groups of order 2 (C2xC2). The focus is on formulating a condition based solely on the elements of the group.

Discussion Character

  • Homework-related, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant states that there are only two groups of order 4: the cyclic group and C2xC2.
  • Another participant questions the need for a specific condition and asks what has been attempted so far.
  • A participant suggests that simply stating the types of groups may not suffice to fill in the blank for the condition.
  • One participant expresses that they are not dealing with a homework question but are looking for a condition regarding the elements of the group.
  • Another participant seeks clarification on what is meant by a condition concerning only the elements of the group, noting that imposing equations might not work due to the nature of the groups.
  • There is a suggestion that more general conditions, such as the elements forming either C4 or C2xC2, may be rejected by the original poster.
  • Concerns are raised about the rejection of conditions that simply state the size of the set of elements.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on what specific condition can be formulated. There are competing views on the nature of the conditions that can be imposed on the elements of the group.

Contextual Notes

Participants express uncertainty about the types of conditions that can be formulated and the implications of those conditions on the classification of groups of order 4.

Kanfoosh
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i need to fill this out:
G is a group of order 4 IFF ___________

i know there are only 2 such groups. the cyclic and the C2xC2
but i need to formulate a condition about the group's elements that can satisfy only one of the two.
 
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If you need to fill it out then it's probably homework, right? Well, what have tried to do? What kind of 'condition'?
 
i know there are only 2 such groups. the cyclic and the C2xC2
What's wrong with using that to fill in the blank?
 
G is the unit group of either Z/5 or Z/8.
 
it's not a homework question, i just thought it's simpler to write it like that

i need a condition that concerns only the elements of the group. i.e. given a group G whose elements all are ________ then |G|=4
perhaps a preceding question should be: is there any such condition?
 
i need a condition that concerns only the elements of the group.
Could you be more explicit in what this means?

Obviously, simply imposing equations won't work. (because C2 and C1 will satisfy any equation satisfied by C4 or C2xC2)

But you seem to reject more general things, like the condidition that the elements form either C4 or C2xC2. And, I presume you'd reject the condition that "the elements form a set of size 4".

So just what sorts of conditions do you have in mind?
 

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