Every ring has a canonical --bimodule structure, with left action and right action defined as the multiplicative binary operation on and biaction defined as the ternary product on :
Let be the category of two-sided ideals in , whose objects are two-sided ideals in , sub---bimodules of with respect to the canonical bimodule structure on , and whose morphisms are --bimodule monomorphisms.
A descending chain of two-sided ideals in is an inverse sequence of two-sided ideals in , a sequence of two-sided ideals with the following dependent sequence of --bimodule monomorphisms: for natural number , a dependent --bimodule monomorphism .
A ring is Artinian if it satisfies the descending chain condition on its two-sided ideals: for every descending chain of two-sided ideals in , there exists a natural number such that for all natural numbers , the --bimodule monomorphism is an --bimodule isomorphism.
Let be the category of left ideals in , whose objects are left ideals in , sub-left--modules of with respect to the canonical left module structure on , and whose morphisms are left -module monomorphisms.
A descending chain of left ideals in is an inverse sequence of left ideals in , a sequence of left ideals with the following dependent sequence of left -module monomorphisms: for natural number , a dependent left -module monomorphism .
A ring is left Artinian if it satisfies the descending chain condition on its left ideals: for every descending chain of left ideals in , there exists a natural number such that for all natural numbers , the left -module monomorphism is an left -module isomorphism.
Let be the category of right ideals in , whose objects are right ideals in , sub-right--modules of with respect to the canonical right module structure on , and whose morphisms are right -module monomorphisms.
A descending chain of right ideals in is an inverse sequence of right ideals in , a sequence of right ideals with the following dependent sequence of right -module monomorphisms: for natural number , a dependent right -module monomorphism .
A ring is right Artinian if it satisfies the descending chain condition on its right ideals: for every descending chain of right ideals in , there exists a natural number such that for all natural numbers , the right -module monomorphism is an right -module isomorphism.
In an artinian ring the Jacobson radical is nilpotent. A left artinian ring is semiprimitive if and only if the zero ideal is the unique nilpotent ideal.
A dual condition is noetherian: a noetherian ring is a ring satisfying the ascending chain condition on ideals. The symmetry is severely broken if one considers unital rings: for example every unital artinian ring is noetherian. For a converse there is a strong condition: a left (unital) ring is left artinian iff is semisimple in and the Jacobson radical is nilpotent. Artinian rings are intuitively much smaller than generic noetherian rings.
artinian object?
commutative ring | reduced ring | integral domain |
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local ring | reduced local ring | local integral domain |
Artinian ring | semisimple ring | field |
Weil ring | field | field |
Last revised on August 19, 2024 at 14:58:15. See the history of this page for a list of all contributions to it.