From the reviews: "This book should be important and useful for students of computer science as an introduction to complexity theory with an emphasis on randomized and approximation algorithms ... . It contains 16 chapters and extends from the foundations of modern complexity theory to recent developments with implications for concrete applications. ... The text is well written ... and the translation is successful." (Gerhard Lischke, Mathematical Reviews, Issue 2006 j) "Complexity theory is an extremely important and vivid field on the border of mathematics and computer science. ... Ingo Wegener certainly created an appealing, well-written book that is a definite choice for the specialists and lecturers when an undergraduate or graduate student asks for guidance into this challenging new field of mathematics." (Peter Hajnal, Acta Scientiarum Mathematicarum, Vol. 71, 2005)