Approximations and Mittag-Leffler conditions the applications

作者：Hugel Lidia Angeleri^*; Saroch Jan; Trlifaj Jan

来源：Israel Journal of Mathematics, 2018, 226(2): 757-780.

DOI：10.1007/s11856-018-1711-3

A classic result by Bass says that the class of all projective modules is covering if and only if it is closed under direct limits. Enochs extended the if-part by showing that every class of modules C, which is precovering and closed under direct limits, is covering, and asked whether the converse is true. We employ the tools developed in [18] and give a positive answer when C = A, or C is the class of all locally A (aeomega) -free modules, where A is any class of modules fitting in a cotorsion pair (A, B) such that B is closed under direct limits. This setting includes all cotorsion pairs and classes of locally free modules arising in (infinite-dimensional) tilting theory. We also consider two particular applications: to pure-semisimple rings, and Artin algebras of infinite representation type.

• 出版日期2018-6