|
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 R. Brauer, K. Morita, T. Nakayama, C. J. Nesbitt, and R. M. Thrall. ==Definitions== For the sake of presentation, it will be easier to define quasi-Frobenius rings first. In the following characterizations of each type of ring, many properties of the ring will be revealed. A ring ''R'' is quasi-Frobenius if and only if ''R'' satisfies any of the following equivalent conditions: # ''R'' is Noetherian on one side and self-injective on one side. # ''R'' is Artinian on a side and self-injective on a side. # All right (or all left) ''R'' modules which are projective are also injective. # All right (or all left) ''R'' modules which are injective are also projective. A Frobenius ring ''R'' is one satisfying any of the following equivalent conditions. Let ''J''=J(''R'') be the Jacobson radical of ''R''. # ''R'' is quasi-Frobenius and the socle as right ''R'' modules. #''R'' is quasi-Frobenius and as left ''R'' modules. # As right ''R'' modules , and as left ''R'' modules . For a commutative ring ''R'', the following are equivalent: # ''R'' is Frobenius # ''R'' is QF # ''R'' is a finite direct sum of local artinian rings which have unique minimal ideals. (Such rings are examples of "zero-dimensional Gorenstein local rings".) A ring ''R'' is right pseudo-Frobenius if any of the following equivalent conditions are met: # Every faithful right ''R'' module is a generator for the category of right ''R'' modules. # ''R'' is right self-injective and is a cogenerator of Mod-''R''. # ''R'' is right self-injective and is finitely cogenerated as a right ''R'' module. # ''R'' is right self-injective and a right Kasch ring. # ''R'' is right self-injective, semilocal and the socle soc(''R''''R'') is an essential submodule of ''R''. # ''R'' is a cogenerator of Mod-''R'' and is a left Kasch ring. A ring ''R'' is right finitely pseudo-Frobenius if and only if every finitely generated faithful right ''R'' module is a generator of Mod-''R''. 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Quasi-Frobenius ring」の詳細全文を読む スポンサード リンク
|