The main focus of this monograph is to offer a comprehensive presentation of known and new results on various generalizations of CS-modules and CS-rings. Extending (or CS) modules are generalizations of injective (and also semisimple or uniform) modules. While the theory of CS-modules is well documented in monographs and textbooks, results on generalized forms of the CS property as well as dual notions are far less present in the literature. With their work the authors provide a solid background to module theory, accessible to anyone familiar with basic abstract algebra. The focus of the book is on direct sums of CS-modules and classes of modules related to CS-modules, such as relative (injective) ejective modules, (quasi) continuous modules, and lifting modules. In particular, matrix CS-rings are studied and clear proofs of fundamental decomposition results on CS-modules over commutative domains are given, thus complementing existing monographs in this area. Open problems round out the work and establish the basis for further developments in the field. The main text is complemented by a wealth of examples and exercises.

Thisvolumeisacollectionof13peerreviewedpapersconsistingofexpository/s- vey articles and research papers by 24 authors. Many of these papers were presented at the International Conference on Ring and Module Theory held at Hacettepe University in Ankara, Turkey, during August 18-22, 2008. The selected papers and articles examine wide ranging and cutting edge - velopments in various areas of Algebra including Ring Theory, Module Theory, Hopf Algebras, and Commutative Algebra. The survey articles are by well-known experts in their respective areas and provide an overview which is useful for - searchers in the area, as well as, for researchers looking for new or related ?elds to investigate. The research papers give a taste of current research. We feel the variety of topics will be of interest to both graduate students and researchers. We wish to thank the large number of conference participants from over 20 countries, the contributors to this volume, and the referees. Encouragement and supportfromHacettepe University,The Scienti?c and TechnologicalResearch .. ? Council of Turkey (TUBITAK) and Republic of Turkey Ministry of Culture and Tourism are greatly appreciated. We also appreciate Evrim Akalan, Sevil Bar?n, .. Canan Celep Yucel, .. Esra Demiryur .. ek, Ozlem Erdo? gan, Fatih Karabacak, Didem Kavalc?,MinePolat,Tu? g, ceSivrikaya,Ay, seS.. onmez,FigenTak?l,MuharremYavuz, Filiz Y?ld?z and Ugu ? r Yucel .. for their assistance and e?cient arrangement of the facilities which greatly contributed to the success of the conference. Finally, we must thank Erkan Afacan of Gazi University for his excellent job of typing and uniformizing manuscripts.

Thisvolumeisacollectionof13peerreviewedpapersconsistingofexpository/s- vey articles and research papers by 24 authors. Many of these papers were presented at the International Conference on Ring and Module Theory held at Hacettepe University in Ankara, Turkey, during August 18-22, 2008. The selected papers and articles examine wide ranging and cutting edge - velopments in various areas of Algebra including Ring Theory, Module Theory, Hopf Algebras, and Commutative Algebra. The survey articles are by well-known experts in their respective areas and provide an overview which is useful for - searchers in the area, as well as, for researchers looking for new or related ?elds to investigate. The research papers give a taste of current research. We feel the variety of topics will be of interest to both graduate students and researchers. We wish to thank the large number of conference participants from over 20 countries, the contributors to this volume, and the referees. Encouragement and supportfromHacettepe University,The Scienti?c and TechnologicalResearch .. ? Council of Turkey (TUBITAK) and Republic of Turkey Ministry of Culture and Tourism are greatly appreciated. We also appreciate Evrim Akalan, Sevil Bar?n, .. Canan Celep Yucel, .. Esra Demiryur .. ek, Ozlem Erdo? gan, Fatih Karabacak, Didem Kavalc?,MinePolat,Tu? g, ceSivrikaya,Ay, seS.. onmez,FigenTak?l,MuharremYavuz, Filiz Y?ld?z and Ugu ? r Yucel .. for their assistance and e?cient arrangement of the facilities which greatly contributed to the success of the conference. Finally, we must thank Erkan Afacan of Gazi University for his excellent job of typing and uniformizing manuscripts.