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  2. Radical of a ring - Wikipedia

    en.wikipedia.org/wiki/Radical_of_a_ring

    In ring theory, a branch of mathematics, a radical of a ring is an ideal of "not-good" elements of the ring. The first example of a radical was the nilradical introduced by Köthe (1930), based on a suggestion of Wedderburn (1908). In the next few years several other radicals were discovered, of which the most important example is the Jacobson ...

  3. Jacobson radical - Wikipedia

    en.wikipedia.org/wiki/Jacobson_radical

    For a general ring with unity R, the Jacobson radical J(R) is defined as the ideal of all elements r ∈ R such that rM = 0 whenever M is a simple R-module.That is, = {=}. This is equivalent to the definition in the commutative case for a commutative ring R because the simple modules over a commutative ring are of the form R / for some maximal ideal of R, and the annihilators of R / in R are ...

  4. Jacobson's conjecture - Wikipedia

    en.wikipedia.org/wiki/Jacobson's_conjecture

    In other words: "The only element of a Noetherian ring in all powers of J is 0." The original conjecture posed by Jacobson in 1956 [ 1 ] asked about noncommutative one-sided Noetherian rings, however Israel Nathan Herstein produced a counterexample in 1965, [ 2 ] and soon afterwards, Arun Vinayak Jategaonkar produced a different example which ...

  5. Ring theory - Wikipedia

    en.wikipedia.org/wiki/Ring_theory

    The concept of the Jacobson radical of a ring; that is, the intersection of all right (left) annihilators of simple right (left) modules over a ring, is one example. The fact that the Jacobson radical can be viewed as the intersection of all maximal right (left) ideals in the ring, shows how the internal structure of the ring is reflected by ...

  6. Radical of an ideal - Wikipedia

    en.wikipedia.org/wiki/Radical_of_an_ideal

    Consider the ring of integers.. The radical of the ideal of integer multiples of is (the evens).; The radical of is .; The radical of is .; In general, the radical of is , where is the product of all distinct prime factors of , the largest square-free factor of (see Radical of an integer).

  7. Semisimple module - Wikipedia

    en.wikipedia.org/wiki/Semisimple_module

    A ring is called Jacobson semisimple (or J-semisimple or semiprimitive) if the intersection of the maximal left ideals is zero, that is, if the Jacobson radical is zero. Every ring that is semisimple as a module over itself has zero Jacobson radical, but not every ring with zero Jacobson radical is semisimple as a module over itself.

  8. Ideal (ring theory) - Wikipedia

    en.wikipedia.org/wiki/Ideal_(ring_theory)

    The factor ring of a maximal ideal is a simple ring in general and is a field for commutative rings. [12] Minimal ideal: A nonzero ideal is called minimal if it contains no other nonzero ideal. Zero ideal: the ideal {}. [13] Unit ideal: the whole ring (being the ideal generated by ). [9]

  9. Nakayama's lemma - Wikipedia

    en.wikipedia.org/wiki/Nakayama's_lemma

    Let J(R) be the Jacobson radical of R. If U is a right module over a ring, R, and I is a right ideal in R, then define U·I to be the set of all (finite) sums of elements of the form u·i, where · is simply the action of R on U. Necessarily, U·I is a submodule of U. If V is a maximal submodule of U, then U/V is simple.