Sylow Theorems and Simple Groups: Proving Non-Simplicity for Groups of Order 96

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In summary, we need to prove that no group of order 96 is simple. This can be done using the Sylow theorems, specifically the third theorem. By considering the index of the normalizer of a 2-Sylow subgroup, we can show that there exists a homomorphism from G to S_3. The action is defined as left multiplication on the normalizer, and the kernel of this map is a normal subgroup. Therefore, if G is simple, the kernel must be trivial, which leads to a contradiction.
  • #1
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Homework Statement


Prove that no group of order 96 is simple.

Homework Equations


The sylow theorems

The Attempt at a Solution


96 = 2^5*3. Using the third Sylow theorem, I know that n_2 = 1 or 3 and n_3 = 1 or 16. I need to show that either n_2 = 1 or n_3 = 1, but I am unsure how to do this.
 
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  • #2
Let H be a 2-Sylow subgroup. Then the index of [itex]N_G(H)[/itex] is 3 by the Sylow theorems.

Can you prove that there exists a homomorphism [itex]G\rightarrow S_3[/itex]??

Hint: define an action by left multiplication on [itex]N_G(H)[/itex].

What can you infer from the kernel being normal?
 
  • #3
I'm not too good at group actions. What would the action be? And where would the homomorphism come from?

If the kernel is normal, then it must be trivial, otherwise there would be a non-trivial normal subgroup of G.
 
  • #4
I gave you the action: left multiplication on [itex]N_G(H)[/itex].
 
  • #5
So does that action look like (g, n) |-> gn where n is in N_G(H)?

Ok, so how about the homomorphism? Do you map an element of g to the action of left multiplication by g on N_G(H)?
 
  • #6
The action is

[tex](g,aN_G(H))\rightarrow gaN_G(H)[/tex]
 
  • #7
So we define the map phi : G -> S_3 by phi(g) = (left multiplication by g).

I can see why this is a homomorphism. (Since left multiplication by g_1g_2 is the same as left multiplication by g_2, then left multiplication by g_1).

Is this right?
 
  • #8
Yes, that is right.

The kernel of this map is a normal subgroup, so what do we get from G being simple?
 

Related to Sylow Theorems and Simple Groups: Proving Non-Simplicity for Groups of Order 96

1. What are Sylow theorems?

Sylow theorems are a set of results in group theory that provide important information about the structure of finite groups. They were developed by the Norwegian mathematician, Ludwig Sylow, in the 19th century.

2. What is the significance of Sylow theorems?

Sylow theorems are important because they allow us to understand the properties and behavior of finite groups, which have numerous applications in fields such as cryptography, chemistry, and physics. They also provide a foundation for other important theorems in group theory.

3. What are simple groups?

Simple groups are groups that do not have any non-trivial normal subgroups. In other words, they cannot be broken down into smaller, simpler groups. Simple groups are the building blocks of finite groups, and understanding their properties is crucial in studying group theory.

4. What is the connection between Sylow theorems and simple groups?

Sylow theorems provide important information about the structure of finite groups, which can be used to classify simple groups. In particular, the third Sylow theorem states that the number of Sylow p-subgroups in a group, where p is a prime number, is congruent to 1 modulo p. This result is used in the proof of the famous Feit-Thompson theorem, which states that every finite group of odd order is solvable.

5. How are Sylow theorems and simple groups used in real-world applications?

The study of Sylow theorems and simple groups has numerous real-world applications. For example, simple groups are used in cryptography to create secure codes and in chemistry to understand the symmetries of molecules. In addition, the classification of finite simple groups has had a significant impact on fields such as computer science and theoretical physics.

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