"The book deals with the construction of knowledge spaces and learning spaces . . Thus, the creative mathematician will find material capable of entertaining him or her for some time. The practitioner may be interested in applications. . there is no doubt that reading and working with this book will be rewarding for the mathematician and useful for scientists from very different areas. In many aspects it has the potential to serve as a guideline to a new and theoretically better founded form of psychometry." (Reinhard Suck, SIAM Review, Vol. 54 (2), 2012)

"This book is an enlarged second edition of the 1999 'Knowledge Spaces' by the same authors. . The authors cover both deterministic and probabilistic models, justify their findings and give good examples and applications, such as pattern recognition and medical diagnosis. . We recommend it to doctoral and postdoctoral studies." (George Stoica, Zentralblatt MATH, Vol. 1205, 2011)