Galois Homework: Proving Prime p^2 Roots of Unity Structure

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In summary, the task is to prove that if p is a prime, then the group (\mathbb{Z}/p^2)^x is isomorphic to C_p \times C_{p-1} \cong C_{p(p-1)}, where C_n represents the cyclic group of order n. The Galois structure of the field of p^2 roots of unity for the cases p=5 and p=7 is to be described, with the question of how many intermediate fields are present in these cases. The proposed solution involves considering a homomorphism from \mathbb{Z}/p^2 to \mathbb{Z}/p and using proof by induction to show that (\mathbb{Z}/p
  • #1
dabien
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Homework Statement



Prove that if p is a prime then [tex](\mathbb{Z}/p^2)^x \cong C_p[/tex] [tex]\times[/tex] [tex]C_{p-1} \cong C_{p(p-1)}[/tex] where [tex]C_n[/tex] denotes the cyclic group of order n.
Next part is to describe the Galois structure of the field of [tex]p^2[/tex] roots of unity, p is prime for the cases of a. p=5, b. p=7. How many intermediate fields are there in these cases?

Homework Equations


The Attempt at a Solution


My idea was to consider a homomorphism [tex]\mathbb{Z}/p^2 \rightarrow \mathbb{Z}/p [/tex] and observe that [tex](\mathbb{Z}/p)^\times[/tex] is a cyclic group of order p-1. Then maybe use proof by induction that if p is an odd prime then [tex](\mathbb{Z}/p^n)^\times[/tex] is cyclic for all n.
 
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  • #2
Then by the isomorphism theorem, there would be an isomorphism between (\mathbb{Z}/p^2)^x and C_p \times C_{p-1} \cong C_{p(p-1)}. Is this correct? For the second part, I'm not sure how to approach it.
 

Related to Galois Homework: Proving Prime p^2 Roots of Unity Structure

1. What is Galois Homework: Proving Prime p^2 Roots of Unity Structure?

Galois Homework: Proving Prime p^2 Roots of Unity Structure is a mathematical problem that involves proving the structure of prime p^2 roots of unity. It is a complex problem that requires advanced knowledge of algebra and number theory.

2. Why is proving the structure of prime p^2 roots of unity important?

Proving the structure of prime p^2 roots of unity is important because it helps us understand the fundamental properties of these numbers. It also has applications in various fields such as cryptography and coding theory.

3. What is the significance of Galois theory in solving this problem?

Galois theory is a branch of abstract algebra that studies the properties of field extensions. It provides a powerful framework and tools for solving problems related to roots of unity, including proving the structure of prime p^2 roots of unity.

4. What are some common techniques used to solve Galois Homework: Proving Prime p^2 Roots of Unity Structure?

Some common techniques used to solve Galois Homework: Proving Prime p^2 Roots of Unity Structure include group theory, field theory, and number theory. These techniques involve using abstract algebraic structures and properties to prove the desired results.

5. How can I strengthen my understanding of this topic?

To strengthen your understanding of Galois Homework: Proving Prime p^2 Roots of Unity Structure, it is recommended to study abstract algebra, number theory, and field theory in depth. Additionally, practicing solving similar problems and seeking guidance from a mentor or teacher can also help improve your understanding of this topic.

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