# Noetherian ring

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A **Noetherian ring** is a ring all of whose ideals are finitely generated.

## Formal definition[edit source]

A ring *R* is said to be a Noetherian ring if every ideal of *R* is finitely generated.

## Examples[edit source]

- The rings , , , and are all examples of Noetherian rings.
- Any field is a Noetherian ring, because its only ideals are the zero ideal and the field itself, which are both obviously finitely generated. In fact, a field is an Artinian ring.
- Any finite ring is a Noetherian ring. In fact, a finite ring is an Artinian ring. In particular, for any positive integer
*n*, the integers mod*n*form a Noetherian ring (in fact, an Artinian ring). - The ring of polynomials in any number of variables with real coefficients is a Noetherian ring.

## Non-examples[edit source]

- The ring of functions from the real numbers to itself is not a Noetherian ring.
- The ring of all algebraic integers is another example of a non-Noetherian ring.
- The ring of polynomials in one variable x with rational coefficients whose constant term is an integer is a third example of a non-Noetherian ring.