Almost free modules and Mittag-Leffler conditions

Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F12%3A10128135" target="_blank" >RIV/00216208:11320/12:10128135 - isvavai.cz</a>
Result on the web
<a href="http://dx.doi.org/10.1016/j.aim.2012.02.013" target="_blank" >http://dx.doi.org/10.1016/j.aim.2012.02.013</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1016/j.aim.2012.02.013" target="_blank" >10.1016/j.aim.2012.02.013</a>

Result language
angličtina
Original language name
Almost free modules and Mittag-Leffler conditions
Original language description
Drinfeld recently suggested to replace projective modules by the flat Mittag-Leffler ones in the definition of an infinite dimensional vector bundle on a scheme X (Drinfeld, 2006 [8]). Two questions arise: (1) What is the structure of the class D of allflat Mittag-Leffler modules over a general ring? (2) Can flat Mittag-Leffler modules be used to build a Quillen model category structure on the category of all chain complexes of quasi-coherent sheaves on X? We answer (1) by showing that a module M is flat Mittag-Leffler, if and only if M is N-1-projective in the sense of Eklof and Mekler (2002) [10]. We use this to characterize the rings such that Disclosed under products, and relate the classes of all Mittag-Leffler, strict Mittag-Leffler, and separable modules. Then we prove that the class D is not deconstructible for any non-right perfect ring. So unlike the classes of all projective and flat modules, the class D does not admit the homotopy theory tools developed recently by Hovey (
Czech name
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Czech description
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Type
J<sub>x</sub> - Unclassified - Peer-reviewed scientific article (Jimp, Jsc and Jost)
CEP classification
BA - General mathematics
OECD FORD branch
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Project
<a href="/en/project/GA201%2F09%2F0816" target="_blank" >GA201/09/0816: Algebraic Methods in the Representation Theory (Approximations, Realizations, and Constraints)</a><br>
Continuities
P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)<br>Z - Vyzkumny zamer (s odkazem do CEZ)

Publication year
2012
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

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