Determine all the ideals of the ring Z

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Discussion Overview

The discussion centers on determining all the ideals of the quotient ring Z[x]/(2,x^3+1). Participants explore the nature of ideals in this context, considering the implications of the quotient structure and the elements involved.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that the ideals may consist of polynomials that are multiples of x^3+1, with their free term being an even number.
  • Another participant challenges this view, proposing that any ideal is the kernel of some homomorphism and that ideals of Z[x]/(2,x^3+1) can be lifted to ideals of Z[x].
  • A different participant notes that the ideals of a quotient ring are those ideals of the original ring that contain the ideal in the bottom of the quotient, specifically looking for ideals of Z[x] that include both x^3+1 and 2.
  • One participant expresses uncertainty about how to express these ideals, questioning whether they must be multiples of x^3+1 and 2.
  • Another participant raises a question about whether a specific ideal contains the element 2, suggesting that it is important to verify this in their exploration.
  • A participant emphasizes the value of explicitly writing out all elements of the small ring to directly work out all of its ideals.
  • Another contribution highlights that the smallest ideal containing two elements consists of all linear combinations of those elements, with coefficients from the ring.

Areas of Agreement / Disagreement

Participants express differing views on the nature of the ideals in the quotient ring, with no consensus reached on the exact characterization of these ideals. The discussion remains unresolved regarding the specifics of the ideals.

Contextual Notes

Participants note that the ring Z[x]/(2,x^3+1) is relatively small, which may allow for explicit enumeration of its elements and ideals. There are also implications regarding the lifting of ideals and the conditions under which certain elements must be included in the ideals.

b0mb0nika
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determine all the ideals of the ring Z[x]/(2,x^3+1)

i'm a bit confused b/c this is a quotient ring.
would the ideals be all the polynomials which are multiples of x^3+1, with their free term an even number ?
 
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I'm not sure what you're saying, but it sounds wrong.

Here are a couple of ideas that might help:

(1) Recall that any ideal is the kernel of some homomorphism...

(2) You can lift any ideal of Z[x]/(2,x^3+1) to an ideal of Z[x]...

(3) Z[x]/(2,x^3+1) is a rather small ring...
 
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the ideals of a quotient ring are those ideals of the original ring that contain the ideal in the bottom of the quotient, so you are looking for all ideals of Z[X] that contain both X^3 +1 and 2.
 
i was thinking kind of the same thing as mathwonk.. but I'm not sure how to write those ideals..
if they contain X^3+1 and 2.. wouldn't they have to be multiples of them ?
 
Does (4) contain 2?

Whatever method you try, I recommend also trying my third suggestion -- the ring is small, so you can explicitly write all of the elements of the ring, and directly work out all of its ideals.
 
Hurkyl's suggestions are always valuable.

Also, remember the elements of the smallest ideal containing u and v, consists of all linear combinations of form au+bv, with a,b, in the ring.
 

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