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Formal definition[edit source]
A ring R is said to be a Noetherian ring if every ideal of R is finitely generated.
- 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.
- 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.