Show that ##G\simeq \mathbb{Z}/2p\mathbb{Z}##

In summary, the conversation discusses proving that a group of order 2p with p as a prime and odd number, and assumed to be abelian, is isomorphic to the group Z/2pZ. It is suggested to show that the group is cyclic and to use the first Sylow theorem, taking into account the fact that all subgroups are normal due to the abelian assumption.
  • #1
JojoF
4
1

Homework Statement


Let ##G## be a group of order ##2p## with p a prime and odd number.

a) We suppose ##G## as abelian. Show that ##G \simeq \mathbb{Z}/2p\mathbb{Z}##

Homework Equations

The Attempt at a Solution


Intuitively I see why but I would like some suggestion of what trajectory I could take to prove this.

I proved in an earlier problem that all groups with a prime order is a cyclic group.
I am sure it is a Sylow theorems problem.

Thanks!
 
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  • #2
JojoF said:

Homework Statement


Let ##G## be a group of order ##2p## with p a prime and odd number.

a) We suppose ##G## as abelian. Show that ##G \simeq \mathbb{Z}/2p\mathbb{Z}##

Homework Equations

The Attempt at a Solution


Intuitively I see why but I would like some suggestion of what trajectory I could take to prove this.

I proved in an earlier problem that all groups with a prime order is a cyclic group.
I am sure it is a Sylow theorems problem.

Thanks!

A (possible) hint: show that ##G## is cyclic and the result will follow because any two cyclic groups of the same order are isomorphic.
 
  • #3
The assumption, that ##G## is Abelian is crucial, as the example with ##p=3## and ##Sym(3)## shows, so this has to play a role in your proof. E.g. all subgroups are automatically normal. I would concentrate on the first Sylow theorem.
 

1. What is the meaning of "##G\simeq \mathbb{Z}/2p\mathbb{Z}##" in mathematical terms?

The notation "##G\simeq \mathbb{Z}/2p\mathbb{Z}##" means that the group G is isomorphic to the group of integers modulo 2p, where p is a prime number. In other words, the two groups have the same structure and can be mapped onto each other in a way that preserves their operations and identities.

2. What is the significance of proving that ##G\simeq \mathbb{Z}/2p\mathbb{Z}##?

Proving that two groups are isomorphic is important because it allows us to understand the structure and properties of one group by studying the other. In this case, showing that ##G\simeq \mathbb{Z}/2p\mathbb{Z}## means that we can use our knowledge of integers modulo 2p to better understand the group G.

3. Can you give an example of a group that is isomorphic to ##\mathbb{Z}/2p\mathbb{Z}##?

Yes, the group of symmetries of a regular p-gon is isomorphic to ##\mathbb{Z}/2p\mathbb{Z}##. This is because the group has p elements and can be represented by rotations and reflections, which can be mapped onto the integers modulo 2p.

4. How is the isomorphism between ##G## and ##\mathbb{Z}/2p\mathbb{Z}## established?

The isomorphism between two groups is established by finding a bijective homomorphism, which is a function that preserves the group operations and identities. In this case, we need to find a function that maps the elements of G onto the integers modulo 2p in a way that preserves the group operations.

5. What are the practical applications of knowing that ##G\simeq \mathbb{Z}/2p\mathbb{Z}##?

The applications of this result can vary depending on the specific group G in question. However, knowing that two groups are isomorphic can help us understand the structure and properties of G, which can have implications in fields such as cryptography, coding theory, and group theory in mathematics.

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