Beiträge zur Algebra und Geometrie Contributions to Algebra and Geometry Vol. 49, No. 2, pp. 399408 (2008) 

Projectivity and flatness over the endomorphism ring of a finitely generated comoduleT. Guédénon1120 avenue Fournier, Québec, QC, G1V 2H8, Canada, email:guedenth@yahoo.caAbstract: Let $k$ be a commutative ring, $A$ a $k$algebra, $\cal C$ an $A$coring that is projective as a left $A$module, $^*{\cal C}$ the dual ring of ${\cal C}$ and $\Lambda$ a right $\cal C$comodule that is finitely generated as a left $^*{\cal C}$module. We give necessary and sufficient conditions for projectivity and flatness of a module over the endomorphism ring $End^{\cal C}(\Lambda)$. If $\cal C$ contains a grouplike element, we can replace $\Lambda$ with $A$. Full text of the article:
Electronic version published on: 18 Sep 2008. This page was last modified: 28 Jan 2013.
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