Give an example of an Artinian ring.
Solution
For any integer \(n\ge2\), the ring \[ \ZZ/n\ZZ \] is Artinian.
Indeed, it is finite. Any descending chain of ideals \[ I_1\supseteq I_2\supseteq I_3\supseteq\cdots \] is therefore a descending chain of subsets of a finite set, so there can be only finitely many strict inclusions. Hence the chain stabilizes.
Thus every finite ring is Artinian, and \(\ZZ/n\ZZ\) is a basic example.