Ideals with subsets and divides

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In summary, if I is a subset of J then that means f is also in J, and by definition of an ideal, g multiplied by some element in J must be equal to an element in J. Therefore, if J is generated by g(x), then f(x) being in J means that g(x) divides f(x).
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phyguy321
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Homework Statement


Let I = <f(x)>, J =<g(x)> be ideals in F[x]. prove that I[tex]\subset[/tex]J [tex]\leftrightarrow[/tex] g(x)|f(x)

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The Attempt at a Solution


If I is a subset of J then does that mean that f is in J also and by definition of an ideal g*some b in J must equal something in J so g|f? because g|f means that f=bg for some b in J
 
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  • #2
phyguy321 said:
If I is a subset of J then does that mean that f is in J
Correct.

also and by definition of an ideal g*some b in J must equal something in J so g|f? because g|f means that f=bg for some b in J
Sort of. I would just use the fact that J is generated by g(x).
 
  • #3
what does it mean that J is generated by g(x)? in layman's terms
 
  • #4
It means J = {a(x)g(x) : a(x) in F[x]}, in other words J is the set of all "multiples" of g(x).
 
  • #5
So if f(x) is in J and J = {a(x)g(x): a(x) in F[x]} then f(x) = a(x)g(x) therefore g(x)|f(x)?
 
  • #6
Correct.
 

1. What is an ideal in mathematics?

An ideal is a subset of a ring that satisfies certain properties. It is a generalization of the concept of a multiple of a number in arithmetic. In a ring, an ideal is a subset that is closed under addition and multiplication by elements of the ring.

2. What is the significance of ideals in mathematics?

Ideals play a crucial role in abstract algebra and commutative algebra. They are used to study the structure and properties of rings, including their factorization and divisibility. Ideals also have applications in number theory, algebraic geometry, and coding theory.

3. How are ideals related to subsets?

An ideal is a special type of subset of a ring. It is a subset that contains the zero element of the ring and is closed under addition and multiplication by elements of the ring. This means that if any element of the ring is multiplied by an element in the ideal, the result will also be in the ideal.

4. What is the difference between a principal ideal and a non-principal ideal?

A principal ideal is generated by a single element of a ring, while a non-principal ideal is generated by multiple elements. In a principal ideal, every element can be written as a multiple of the generator, while in a non-principal ideal, this may not be possible.

5. How do ideals relate to the concept of divisibility?

In a ring, an ideal can be thought of as a generalization of the concept of divisibility. If an element of a ring belongs to an ideal, it can be divided by any element in the ideal without leaving the ring. This is similar to how a number is divisible by its multiples in arithmetic.

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