Is Z7[x] isomorphic to Z?

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In summary, isomorphism in mathematics refers to a one-to-one correspondence between two mathematical structures, preserving their operations and relationships. In the context of Z7[x] and Z, this means that every polynomial in Z7[x] can be matched with a unique integer in Z, allowing for more efficient problem-solving and proofs. To prove the isomorphism between these two structures, a function is typically defined. There can only be one isomorphism between Z7[x] and Z, as multiple isomorphisms would not fulfill the one-to-one correspondence requirement.
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jouiswalker
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Homework Statement



Let R = Z7[x]. Show that R is not isomorphic to Z.

Homework Equations


The Attempt at a Solution



One of the necessary conditions for an isomorphism f is that f be one to one. So consider 8x in Z. f(8x) = x, f(1x) = x. So f cannot be an isomorphism. I'm clearly missing something though, since this seems a bit too easy.
 
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  • #2
Actually nevermind, it is that easy. There's a hint hidden that basically says "an isomorphism has to be one to one..."
 

1. What is isomorphism in mathematics?

Isomorphism is a mathematical concept that refers to a one-to-one correspondence between two mathematical structures, such as groups, rings, or fields. This means that there is a way to match every element in one structure with a unique element in the other structure in a way that preserves their operations and relationships.

2. How does isomorphism apply to Z7[x] and Z?

In the context of Z7[x] and Z, isomorphism refers to the existence of a one-to-one correspondence between the elements of these two structures. This means that there is a way to match every polynomial in Z7[x] with a unique integer in Z, while preserving their addition, subtraction, and multiplication operations.

3. What is the significance of isomorphism between Z7[x] and Z?

The isomorphism between Z7[x] and Z allows us to view these two structures as essentially the same, even though they may appear different at first glance. This allows us to transfer knowledge and techniques from one structure to the other, making problem-solving and proofs more efficient and streamlined.

4. How can we prove that there is an isomorphism between Z7[x] and Z?

To prove that there is an isomorphism between Z7[x] and Z, we need to show that there is a function that maps every element in Z7[x] to a unique element in Z, while preserving their operations. This function is typically defined as f(a0 + a1x + a2x^2 + ... + anx^n) = a0 + a1 + a2 + ... + an.

5. Can there be more than one isomorphism between Z7[x] and Z?

No, there can only be one isomorphism between Z7[x] and Z. This is because the definition of isomorphism requires a one-to-one correspondence between the elements of the two structures, meaning that each element must have a unique match in the other structure. If there were more than one isomorphism, this one-to-one correspondence would not hold.

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