Approximations and Endomorphism Algebras of Modules : : Volume 1 – Approximations / Volume 2 – Predictions / / Rüdiger Göbel, Jan Trlifaj.

• Superior document: Title is part of eBook package: De Gruyter DG Expositions in Mathematics Backlist eBook Package
• VerfasserIn: Göbel, Rüdiger,; Trlifaj, Jan,
• Place / Publishing House: Berlin ;, Boston : : De Gruyter, , [2012]; ©2012
• Year of Publication: 2012
• Edition: 2nd rev. and exp. ed.
• Language: English
• Series: De Gruyter Expositions in Mathematics , 41
• Physical Description: 1 online resource (972 p.)

This second, revised and substantially extended edition of Approximations and Endomorphism Algebras of Modules reflects both the depth and the width of recent developments in the area since the first edition appeared in 2006. The new division of the monograph into two volumes roughly corresponds to its two central topics, approximation theory (Volume 1) and realization theorems for modules (Volume 2). It is a widely accepted fact that the category of all modules over a general associative ring is too complex to admit classification. Unless the ring is of finite representation type we must limit attempts at classification to some restricted subcategories of modules. The wild character of the category of all modules, or of one of its subcategories C, is often indicated by the presence of a realization theorem, that is, by the fact that any reasonable algebra is isomorphic to the endomorphism algebra of a module from C. This results in the existence of pathological direct sum decompositions, and these are generally viewed as obstacles to classification. In order to overcome this problem, the approximation theory of modules has been developed. The idea here is to select suitable subcategories C whose modules can be classified, and then to approximate arbitrary modules by those from C. These approximations are neither unique nor functorial in general, but there is a rich supply available appropriate to the requirements of various particular applications. The authors bring the two theories together. The first volume, Approximations, sets the scene in Part I by introducing the main classes of modules relevant here: the S-complete, pure-injective, Mittag-Leffler, and slender modules. Parts II and III of the first volume develop the key methods of approximation theory. Some of the recent applications to the structure of modules are also presented here, notably for tilting, cotilting, Baer, and Mittag-Leffler modules. In the second volume, Predictions, further basic instruments are introduced: the prediction principles, and their applications to proving realization theorems. Moreover, tools are developed there for answering problems motivated in algebraic topology. The authors concentrate on the impossibility of classification for modules over general rings. The wild character of many categories C of modules is documented here by the realization theorems that represent critical R-algebras over commutative rings R as endomorphism algebras of modules from C. The monograph starts from basic facts and gradually develops the theory towards its present frontiers. It is suitable both for graduate students interested in algebra and for experts in module and representation theory.

Table of Contents

Frontmatter -- Contents -- Introduction -- List of Symbols -- Part I. Some useful classes of modules -- Chapter 1. S-completions -- Chapter 2. Pure-injective modules -- Chapter 3. Mittag-Leffler modules -- Chapter 4. Slender modules -- Part II. Approximations and cotorsion pairs -- Chapter 5. Approximations of modules -- Chapter 6. Complete cotorsion pairs -- Chapter 7. Hill lemma and its applications -- Chapter 8. Deconstruction of the roots of Ext -- Chapter 9. Modules of projective dimension one -- Chapter 10. Kaplansky classes and abstract elementary classes -- Chapter 11. Independence results for cotorsion pairs -- Chapter 12. The lattice of cotorsion pairs -- Part III. Tilting and cotilting approximations -- Chapter 13. Tilting approximations -- Chapter 14. 1-tilting modules and their applications -- Chapter 15. Cotilting classes -- Chapter 16. Tilting and cotilting classes over commutative noetherian rings -- Chapter 17. Tilting approximations and the finitistic dimension conjectures -- Bibliography -- Index -- Part IV Prediction principles -- Chapter 18. Survey of prediction principles using ZFC and more -- Chapter 19. Prediction principles in ZFC: the Black Boxes and others -- Part V. Endomorphism algebras and automorphism groups -- Chapter 20. Realising algebras – by algebraically independent elements and by prediction principles -- Chapter 21. Automorphism groups of torsion-free abelian groups -- Chapter 22. Modules with distinguished submodules -- Chapter 23. R-modules and fields from modules with distinguished submodules -- Chapter 24 Endomorphism algebras of אn-free modules -- Part VI. Modules and rings related to algebraic topology -- Chapter 25. Localisations and cellular covers, the general theory for R-modules -- Chapter 26. Tame and wild localisations of size ≤ 2 ℵ0 -- Chapter 27. Tame cellular covers -- Chapter 28. Wild cellular covers -- Chapter 29. Absolute E-rings -- Part VII. Cellular covers, localisations and E(R)-algebras -- Chapter 30. Large kernels of cellular covers and large localisations -- Chapter 31. Mixed E(R)-modules over Dedekind domains -- Chapter 32. E(R)-modules with cotorsion -- Chapter 33. Generalised E(R)-algebras -- Chapter 34. Some more useful classes of algebras -- Bibliography -- Index