This study is concerned with computing the homotopy classes of maps algebraically and determining the law of composition for such maps. The problem is solved by introducing new algebraic models of a 4-manifold. Including a complete list of references for the text, the book appeals to researchers and graduate students in topology and algebra. "This book is clearly the last word on the homotopy category of simply-connected 4-mannifolds and related spaces. It should prove indispensable to workers in the area." AMS Mathematical Reviews, Laurence R. Taylor Homotopy of 4-manifolds for researchers and graduate students. Used Book in Good Condition