Brown (emeritus computer science, Bangor U., Wales) Philip J. Higgins (emeritus Durham U. England) and Rafael Sivera (geometry and topology, U. de València, Spain) explain some basic algebraic topology at the border between homology and homotopy, at a level accessible to graduate students acquainted with general topology, the fundamental group, notions of homotopy, and some basic methods of category theory. Among the topics are homotopy theory and crossed modules, induced crossed modules, the higher homotopy Seifert-van Kampen theorem and its applications, the cubical classifying space of a crossed complex, and tensor products and homotopies. Annotation ©2011 Book News, Inc., Portland, OR (booknews.com)