Prest, Mike
(2005)
*Ideals in mod-R and the ω-radical.*
Journal of the London Mathematical Society, 71 (2).
pp. 321-334.
ISSN 0024-6107

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## Abstract

Let $R$ be an artin algebra, and let mod-$R$ denote the category of finitely presented right $R$-modules. The radical ${\rm rad}={\rm rad}({\rm mod}\mbox{-}R)$ of this category and its finite powers play a major role in the representation theory of $R$. The intersection of these finite powers is denoted ${\rm rad}^\omega$, and the nilpotence of this ideal has been investigated, in $[{\bf 6}$, ${\bf 13}]$ for instance. In $[{/bf 17}]$, arbitrary transfinite powers, ${\rm rad}^\alpha$, of rad were defined and linked to the extent to which morphisms in ${\rm mod}\mbox{-}R$ may be factorised. In particular, it has been shown that if $R$ is an artin algebra, then the transfinite radical, ${\rm rad}^\infty $, the intersection of all ordinal powers of rad, is non-zero if and only if there is a ‘factorisable system’ of morphisms in rad and, in that case, the Krull–Gabriel dimension of ${\rm mod}\mbox{-}R$ equals $\infty$ (that is, is undefined). More precise results on the index of nilpotence of rad for artin algebras were proved in $[{\bf 14}$, ${/bf 20}$, ${/bf 24}\hbox{--}{/bf 26}]$.

Item Type: | Article |
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Subjects: | MSC 2010, the AMS's Mathematics Subject Classification > 16 Associative rings and algebras |

Depositing User: | Professor Mike Prest |

Date Deposited: | 22 May 2006 |

Last Modified: | 20 Oct 2017 14:12 |

URI: | http://eprints.maths.manchester.ac.uk/id/eprint/279 |

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