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Quasi-Frobenius Ring
In mathematics, especially ring theory, the class of Frobenius rings and their generalizations are the extension of work done on Frobenius algebras. Perhaps the most important generalization is that of quasi-Frobenius rings (QF rings), which are in turn generalized by right pseudo-Frobenius rings (PF rings) and right finitely pseudo-Frobenius rings (FPF rings). Other diverse generalizations of quasi-Frobenius rings include QF-1, QF-2 and QF-3 rings. These types of rings can be viewed as descendants of algebras examined by Georg Frobenius. A partial list of pioneers in quasi-Frobenius rings includes Richard Brauer, R. Brauer, Kiiti Morita, K. Morita, Tadashi Nakayama (mathematician), T. Nakayama, Cecil J. Nesbitt, C. J. Nesbitt, and Robert M. Thrall, R. M. Thrall. Definitions A ring ''R'' is quasi-Frobenius if and only if ''R'' satisfies any of the following equivalent conditions: # ''R'' is noetherian ring, Noetherian on one side and injective module#Self-injective rings, self-in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ring Theory
In algebra, ring theory is the study of rings— algebraic structures in which addition and multiplication are defined and have similar properties to those operations defined for the integers. Ring theory studies the structure of rings, their representations, or, in different language, modules, special classes of rings (group rings, division rings, universal enveloping algebras), as well as an array of properties that proved to be of interest both within the theory itself and for its applications, such as homological algebra, homological properties and Polynomial identity ring, polynomial identities. Commutative rings are much better understood than noncommutative ones. Algebraic geometry and algebraic number theory, which provide many natural examples of commutative rings, have driven much of the development of commutative ring theory, which is now, under the name of ''commutative algebra'', a major area of modern mathematics. Because these three fields (algebraic geometry, alge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Faithful Module
In mathematics, the annihilator of a subset of a module over a ring is the ideal formed by the elements of the ring that give always zero when multiplied by an element of . Over an integral domain, a module that has a nonzero annihilator is a torsion module, and a finitely generated torsion module has a nonzero annihilator. The above definition applies also in the case noncommutative rings, where the left annihilator of a left module is a left ideal, and the right-annihilator, of a right module is a right ideal. Definitions Let ''R'' be a ring, and let ''M'' be a left ''R''-module. Choose a non-empty subset ''S'' of ''M''. The annihilator of ''S'', denoted Ann''R''(''S''), is the set of all elements ''r'' in ''R'' such that, for all ''s'' in ''S'', . In set notation, :\mathrm_R(S)=\ It is the set of all elements of ''R'' that "annihilate" ''S'' (the elements for which ''S'' is a torsion set). Subsets of right modules may be used as well, after the modification of "" in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quasi-Frobenius Lie Algebra
In mathematics, a quasi-Frobenius Lie algebra :(\mathfrak, ,\,\,,\,\,\,\beta ) over a field k is a Lie algebra :(\mathfrak, ,\,\,,\,\,\,) equipped with a nondegenerate skew-symmetric bilinear form :\beta : \mathfrak\times\mathfrak\to k, which is a Lie algebra 2- cocycle of \mathfrak with values in k. In other words, :: \beta \left(\left ,Y\rightZ\right)+\beta \left(\left ,X\rightY\right)+\beta \left(\left ,Z\rightX\right)=0 for all X, Y, Z in \mathfrak. If \beta is a coboundary, which means that there exists a linear form f : \mathfrak\to k such that :\beta(X,Y)=f(\left ,Y\right, then :(\mathfrak, ,\,\,,\,\,\,\beta ) is called a Frobenius Lie algebra. Equivalence with pre-Lie algebras with nondegenerate invariant skew-symmetric bilinear form If (\mathfrak, ,\,\,,\,\,\,\beta ) is a quasi-Frobenius Lie algebra, one can define on \mathfrak another bilinear product \triangleleft by the formula :: \beta \left(\left ,Y\rightZ\right)=\beta \left(Z \triangleleft Y,X \right) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Serial Module
In abstract algebra, a uniserial module ''M'' is a module over a ring ''R'', whose submodules are totally ordered by inclusion. This means simply that for any two submodules ''N''1 and ''N''2 of ''M'', either N_1\subseteq N_2 or N_2\subseteq N_1. A module is called a serial module if it is a direct sum of uniserial modules. A ring ''R'' is called a right uniserial ring if it is uniserial as a right module over itself, and likewise called a right serial ring if it is a right serial module over itself. Left uniserial and left serial rings are defined in an analogous way, and are in general distinct from their right counterparts. An easy motivating example is the quotient ring \mathbb/n\mathbb for any integer n>1. This ring is always serial, and is uniserial when ''n'' is a prime power. The term ''uniserial'' has been used differently from the above definition: for clarification see below. A partial alphabetical list of important contributors to the theory of serial rings inclu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quotient Ring
In ring theory, a branch of abstract algebra, a quotient ring, also known as factor ring, difference ring or residue class ring, is a construction quite similar to the quotient group in group theory and to the quotient space in linear algebra. It is a specific example of a quotient, as viewed from the general setting of universal algebra. Starting with a ring and a two-sided ideal in , a new ring, the quotient ring , is constructed, whose elements are the cosets of in subject to special and operations. (Only the fraction slash "/" is used in quotient ring notation, not a horizontal fraction bar.) Quotient rings are distinct from the so-called "quotient field", or field of fractions, of an integral domain as well as from the more general "rings of quotients" obtained by localization. Formal quotient ring construction Given a ring and a two-sided ideal in , we may define an equivalence relation on as follows: : if and only if is in . Using the ideal properties, it is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semisimple Ring
In mathematics, especially in the area of abstract algebra known as module theory, a semisimple module or completely reducible module is a type of module that can be understood easily from its parts. A ring that is a semisimple module over itself is known as an Artinian semisimple ring. Some important rings, such as group rings of finite groups over fields of characteristic zero, are semisimple rings. An Artinian ring is initially understood via its largest semisimple quotient. The structure of Artinian semisimple rings is well understood by the Artin–Wedderburn theorem, which exhibits these rings as finite direct products of matrix rings. For a group-theory analog of the same notion, see ''Semisimple representation''. Definition A module over a (not necessarily commutative) ring is said to be semisimple (or completely reducible) if it is the direct sum of simple (irreducible) submodules. For a module ''M'', the following are equivalent: # ''M'' is semisimple; i.e., a dir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Injective Hull
In mathematics, particularly in algebra, the injective hull (or injective envelope) of a module is both the smallest injective module containing it and the largest essential extension of it. Injective hulls were first described in . Definition A module ''E'' is called the injective hull of a module ''M'', if ''E'' is an essential extension of ''M'', and ''E'' is injective. Here, the base ring is a ring with unity, though possibly non-commutative. Examples * An injective module is its own injective hull. * The injective hull of an integral domain is its field of fractions . * The injective hull of a cyclic ''p''-group (as Z-module) is a Prüfer group . * The injective hull of ''R''/rad(''R'') is Hom''k''(''R'',''k''), where ''R'' is a finite-dimensional ''k''-algebra with Jacobson radical rad(''R'') . * A simple module is necessarily the socle of its injective hull. * The injective hull of the residue field of a discrete valuation ring (R,\mathfrak,k) where \mathfrak = x\cdot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Balanced Module
In the subfield of abstract algebra known as module theory, a right ''R'' module ''M'' is called a balanced module (or is said to have the double centralizer property) if every endomorphism of the abelian group ''M'' which commutes with all ''R''-endomorphisms of ''M'' is given by multiplication by a ring element. Explicitly, for any additive endomorphism ''f'', if ''fg'' = ''gf'' for every ''R'' endomorphism ''g'', then there exists an ''r'' in ''R'' such that ''f''(''x'') = ''xr'' for all ''x'' in ''M''. In the case of non-balanced modules, there will be such an ''f'' that is not expressible this way. In the language of centralizers, a balanced module is one satisfying the conclusion of the double centralizer theorem, that is, the only endomorphisms of the group ''M'' commuting with all the ''R'' endomorphisms of ''M'' are the ones induced by right multiplication by ring elements. A ring is called balanced if every right ''R'' module is balanced.The definitions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Finitely Generated Module
In mathematics, a finitely generated module is a module that has a finite generating set. A finitely generated module over a ring ''R'' may also be called a finite ''R''-module, finite over ''R'', or a module of finite type. Related concepts include finitely cogenerated modules, finitely presented modules, finitely related modules and coherent modules all of which are defined below. Over a Noetherian ring the concepts of finitely generated, finitely presented and coherent modules coincide. A finitely generated module over a field is simply a finite-dimensional vector space, and a finitely generated module over the integers is simply a finitely generated abelian group. Definition The left ''R''-module ''M'' is finitely generated if there exist ''a''1, ''a''2, ..., ''a''''n'' in ''M'' such that for any ''x'' in ''M'', there exist ''r''1, ''r''2, ..., ''r''''n'' in ''R'' with ''x'' = ''r''1''a''1 + ''r''2''a''2 + ... + ''r''''n''''a''''n''. The set is referred to as a generating ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Essential Submodule
In mathematics, specifically module theory, given a ring ''R'' and an ''R''-module ''M'' with a submodule ''N'', the module ''M'' is said to be an essential extension of ''N'' (or ''N'' is said to be an essential submodule or large submodule of ''M'') if for every submodule ''H'' of ''M'', :H\cap N=\\, implies that H=\\, As a special case, an essential left ideal of ''R'' is a left ideal that is essential as a submodule of the left module ''R''''R''. The left ideal has non-zero intersection with any non-zero left ideal of ''R''. Analogously, an essential right ideal is exactly an essential submodule of the right ''R'' module ''R''''R''. The usual notations for essential extensions include the following two expressions: :N\subseteq_e M\, , and N\trianglelefteq M The dual notion of an essential submodule is that of superfluous submodule (or small submodule). A submodule ''N'' is superfluous if for any other submodule ''H'', :N+H=M\, implies that H=M\,. The usual notations for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semilocal Ring
In mathematics, a semi-local ring is a ring for which ''R''/J(''R'') is a semisimple ring, where J(''R'') is the Jacobson radical of ''R''. The above definition is satisfied if ''R'' has a finite number of maximal right ideals (and finite number of maximal left ideals). When ''R'' is a commutative ring, the converse implication is also true, and so the definition of semi-local for commutative rings is often taken to be "having finitely many maximal ideals". Some literature refers to a commutative semi-local ring in general as a ''quasi-semi-local ring'', using semi-local ring to refer to a Noetherian ring with finitely many maximal ideals. A semi-local ring is thus more general than a local ring, which has only one maximal (right/left/two-sided) ideal. Examples * Any right or left Artinian ring, any serial ring, and any semiperfect ring is semi-local. * The quotient \mathbb/m\mathbb is a semi-local ring. In particular, if m is a prime power, then \mathbb/m\mathbb is a local ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kasch Ring
In ring theory, a subfield of abstract algebra, a right Kasch ring is a ring ''R'' for which every simple right ''R'' module is isomorphic to a right ideal of ''R''. Analogously the notion of a left Kasch ring is defined, and the two properties are independent of each other. Kasch rings are named in honor of mathematician Friedrich Kasch. Kasch originally called Artinian rings whose proper ideals have nonzero annihilators ''S-rings''. The characterizations below show that Kasch rings generalize S-rings. Definition Equivalent definitions will be introduced only for the right-hand version, with the understanding that the left-hand analogues are also true. The Kasch conditions have a few equivalent statements using the concept of annihilators, and this article uses the same notation appearing in the annihilator article. In addition to the definition given in the introduction, the following properties are equivalent definitions for a ring ''R'' to be right Kasch. They appear in : # ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |