Need help checking a proof on a cyclic group

You have correctly shown that p/(2q) cannot be generated by an integer k, which means that (Q,+) cannot be cyclic. Your proof is thorough and makes sense. Good job!
  • #1
Prometheos
13
0
1. Prove that (Q,+) is not cyclic



Here is what I have, and I need help knowing if this proof makes sense, is thorough enough, or is completely wrong. Note that (Q,+) is rationals

Suppose, by contradiction, that (Q,+) is cyclic, p/q E (Q,+) and q=/=0
=> (Q,+) can be generated by <p/q> = {k(p/q)|k E Z}
if p/(2q) E (Q,+)
then p/(2q) can be generated by k(p/q)
=> p/(2q)=k(p/q)
1/2=k
therefore k does not belong to Z and (Q,+) is not cyclic

It seems like I am missing something or made a conceptual error somewhere. Any help or confirmation is appreciated.
 
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  • #2
Looks good to me
 

1. What is a cyclic group?

A cyclic group is a mathematical structure that consists of a set of elements and a binary operation that combines two elements to produce a third element. The elements in a cyclic group are generated by a single element called a generator, and the group is called cyclic because the elements can be "cycled" through by repeatedly applying the binary operation.

2. How do you prove that a group is cyclic?

To prove that a group is cyclic, you need to show that there exists an element in the group that can generate all other elements through repeated applications of the group operation. This element is called a generator, and if it exists, the group is considered cyclic.

3. What is the order of a cyclic group?

The order of a cyclic group is the number of elements in the group. For example, a cyclic group with a generator of 2 will have an order of 2 if it only contains the elements 1 and 2. The order of a cyclic group can also be infinite if there is no limit to the elements that can be generated.

4. How do you check a proof on a cyclic group?

To check a proof on a cyclic group, you need to carefully examine each step of the proof and make sure it follows logically from the definitions and properties of cyclic groups. You can also try to apply the proof to a specific example of a cyclic group to see if it holds true.

5. What are some common mistakes when proving a cyclic group?

Common mistakes when proving a cyclic group include assuming that all elements in the group are generated by a single element without proper justification, using incorrect definitions or properties of cyclic groups, and making mathematical errors in calculations or equations. It is important to be thorough and precise when proving a cyclic group to avoid these mistakes.

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