Prove G is Cyclic: Prime p Order Group

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In summary, to prove that a group G with order p is cyclic, we can pick an element g of G that is not the identity and show that the subgroup generated by g is equal to G. This is possible because for a prime p, the only possible subgroups of G are {e} and G itself. Additionally, we can use the fact that Lagrange's theorem states that the order of a subgroup must divide the order of the group. Therefore, if the subgroup generated by g has order p, it must be equal to G.
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catherinenanc
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1. Let p be a prime and G a group whose order is p. Prove that G is cyclic.



2. I know that if p is prime, then the only possible subgroups of G are {e} and G itself. But, how to use this fact to show that G is cyclic?
 
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  • #2
Pick an element g of G that is not e and consider the subgroup generated by g.
 
  • #3
HINT: Lagrange
 
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  • #4
Dick said:
Pick an element g of G that is not e and consider the subgroup generated by g.

Ok, this may sound stupid, but, how do I know that <g>=G?
 
  • #5
catherinenanc said:
Ok, this may sound stupid, but, how do I know that <g>=G?

Oh, wait, there are only two subgroups,so it has to be.

Thanks!
 

FAQ: Prove G is Cyclic: Prime p Order Group

How do you prove that G is cyclic?

To prove that G is cyclic, we need to show that there exists an element g in G such that every element in G can be written as a power of g. This can be done by showing that the order of g is equal to the order of the group G.

What is a prime p order group?

A prime p order group is a group in which the number of elements is a prime number p. This means that the group has exactly p elements and every element in the group has an order that is a factor of p.

How can you determine the order of a group?

The order of a group is equal to the number of elements it contains. This can be determined by counting the number of elements in the group or by using a formula, such as Lagrange's theorem, which states that the order of any subgroup must divide the order of the group.

Can a group be cyclic if it is not of prime p order?

Yes, a group can be cyclic even if it is not of prime p order. For a group to be cyclic, there just needs to exist an element g in the group such that every element can be written as a power of g. This does not depend on the order of the group.

What is the significance of proving that a group is cyclic?

Proving that a group is cyclic can provide insight into the structure of the group and can also make certain calculations and proofs easier. Additionally, cyclic groups have many important applications in mathematics and other fields, making it a useful concept to understand.

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