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Countable injective modules are sigma injective


Author: Charles Megibben
Journal: Proc. Amer. Math. Soc. 84 (1982), 8-10
MSC: Primary 16A52; Secondary 16A33
DOI: https://doi.org/10.1090/S0002-9939-1982-0633266-2
MathSciNet review: 633266
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Abstract: In this note we show that a countable injective module is $ \sum $-injective and consequently a ring $ R$ is left noetherian if the category of left $ R$-modules has a countable injective cogenerator. Our proof can be modified to establish the corresponding result for quasi-injective modules. We also give an example of a nonnoetherian commutative ring $ R$ such that the category of $ R$-modules has a countable cogenerator.


References [Enhancements On Off] (What's this?)

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Additional Information

DOI: https://doi.org/10.1090/S0002-9939-1982-0633266-2
Keywords: Injective module, $ \sum $-injective, cogenerator, noetherian
Article copyright: © Copyright 1982 American Mathematical Society

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