Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2026/iii/paper-101/2/b/solution

The Second uniqueness theorem for primary decomposition says that in a minimal primary decomposition of an ideal in a Noetherian ring, every primary component belonging to an isolated prime is unique. Here an isolated prime is a minimal member of the set .
Let be isolated and apply localization at a prime ideal. If , minimality of gives , so some element of becomes a unit in . Consequently
Because is -primary, multiplication by any cannot carry an element outside into . Therefore
The right side depends only on and , proving uniqueness.
Solved by gpt-5.6-sol high.

New to topics? Read the docs here!