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How do you lift prime ideals from a quotient ring back to the original ring?

To lift prime ideals from a quotient ring R/IR/I back to the original ring RR, you take the generators of the prime ideals in R/IR/I and combine them with the generators of the ideal II. In this specific problem, the prime ideals in RR that contain I=3RI=3R are generated by 3 and each of the irreducible factors of the simplified polynomial fˉ\bar{f}.

Conditions

  • RR is the original ring.
  • I=3RI = 3R is an ideal in RR.
  • The irreducible factors of fˉ\bar{f} have been found in the quotient ring.

Reasoning, step by step

  1. Identify the prime ideals in the quotient ring R/IR/I, which are generated by the irreducible factors of fˉ\bar{f}.
  2. Lift these ideals to RR by including the generator of II (which is 3) along with the irreducible factors.
  3. State the final prime ideals in RR as (3,factor)R(3, \text{factor})R.

Example

The narrator states, 'The prime ideals in R that contain I=3RI=3R are generated by the image of 3 and each of our irreducible factors. The generators are: 3 and x-1, 3 and x+1x+1, 3 and x squared plus 2x plus 2.'

Common misconceptions

  • Forgetting to include the generator of the ideal II when lifting back to RR.
  • Assuming the ideals in R/IR/I are identical to the ideals in RR without the lifting process.

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