Bifibration of reduced quadratic modules

This thesis consists of four chapters. In the first chapter, it is given that the concepts as category, grupoid, fibration, cofibration and stated explaining examples and propositions about these concepts. Besides pullback and pushout concepts are told and associated with fibration and cofibration of grupoids. In the second chapter, a crossed module concept is presented, a crossed module on grupoids are briefly stated. In the third chapter, firstly precrossed module, nil(2)_module and reduced quadratic module concepts are given, later a fibration of reduced quadratic modules is founded. The necessary stages for this are explained in detail. In the final chapter, a construction of induced quadratic modules is demonstrated. A cofibration of reduced qaudratic modules is founded telling necessary stages.