Abraham Ungar (North Dakota State University, ND) is Professor of Mathematics at North Dakota State University. He specializes in the areas of linear algebra, geometry and physics. He has published seven books and over 100 papers, mostly in indexed journals.
This monograph is a synthesis of the author's work on gyrogroups and gyrovector spaces (since 1988) as well as on their generalizations, the bi-gyrogroups and bi-gyrovector spaces. ...This very original but highly technical book starts with an interesting modelization of the Einstein addition of the velocities in the relativistic setting, by considering it as the (nonassociative) composition law of a special groupoid, called gyrogroup. --zbMATh