How statement and proof provenance work
The first chip identifies the source of the statement or construction; the second identifies the source of its local proof or verification.
- Literature-sourced: the exact statement appears in a cited source; only wording and notation differ.
- AI-adapted: a semantically identical restatement of literature-sourced material, modulo indexing, notation, and boundary cases adopted by the library.
- AI-generated: a genuinely novel statement formulated by AI, with no source for the claim itself.
These labels describe origin, not correctness: citations and verification chips remain separate evidence.
The ring is zero-dimensional but not Noetherian
Example
Let
Then every prime ideal of is maximal, so has Krull dimension , but is not Noetherian.
Facts & Assumptions
Given: The ring .
Verification
Every element is idempotent, because coordinatewise in . Let be a prime ideal of . Then is an integral domain if and only if is a prime ideal makes an integral domain, and every class still satisfies . So forces or . Thus has exactly two elements and is a field, so is maximal.
For each , let be the sequence with in coordinate and elsewhere, and let . Then is a strict ascending chain of ideals, because for every . Therefore is not Noetherian.
Let The first-coordinate projection is a surjective ring homomorphism with kernel , so is a field and therefore an integral domain. Thus is an integral domain if and only if is a prime ideal makes a prime ideal. By step 1.1 every prime ideal of is maximal, so no strict chain of prime ideals can have length greater than . Since provides a prime ideal, chains of length do occur. Therefore Krull dimension of a nonzero ring gives . Together with step 2.1, this ring is zero-dimensional but not Noetherian, so it is a concrete witness that the Noetherian hypothesis in the prime-maximal Artinian criterion cannot be dropped.
Depends on
Used by
Nothing in the library uses this result yet.
Dependency tree · two levels
6 results within two dependency steps of this one, each drawn at its shortest distance from it. An arrow runs from a result to what uses it, so the chart reads left to right and ends at this result, which carries a heavier outline. Every node is a link to that result. Click elsewhere on the chart to enlarge it.
Sources
- The Stacks Project, Section 15.106: Weakly étale ring maps (standard reference, not scraped)
- The Stacks Project, Section 10.53: Artinian rings (standard reference, not scraped)