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arXiv · 1007.4977

Flat Mittag-Leffler modules over countable rings

Silvana Bazzoni·Jan Stovicek
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Abstract

We show that over any ring, the double Ext-orthogonal class to all flat Mittag-Leffler modules contains all countable direct limits of flat Mittag-Leffler modules. If the ring is countable, then the double orthogonal class consists precisely of all flat modules and we deduce, using a recent result of \v{S}aroch and Trlifaj, that the class of flat Mittag-Leffler modules is not precovering in Mod-R unless R is right perfect.

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BibTeXRIS

Silvana Bazzoni, Jan Stovicek. 2010-07-28. Flat Mittag-Leffler modules over countable rings. https://doi.org/10.1090/s0002-9939-2011-11070-0

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