In this volume readers will find for the first time a detailed account of the theory of symplectic reduction by stages, along with numerous illustrations of the theory. Special emphasis is given to group extensions, including a detailed discussion of the Euclidean group, the oscillator group, the Bott-Virasoro group and other groups of matrices. Ample background theory on symplectic reduction and cotangent bundle reduction in particular is provided. Novel features of the book are the inclusion of a systematic treatment of the cotangent bundle case, including the identification of cocycles with magnetic terms, as well as the general theory of singular reduction by stages.

This volume provides a detailed account of the theory of symplectic reduction by stages, along with numerous illustrations of the theory. It gives special emphasis to group extensions, including a detailed discussion of the Euclidean group, the oscillator group, the Bott-Virasoro group and other groups of matrices. The volume also provides ample background theory on symplectic reduction and cotangent bundle reduction.

Background and the Problem Setting.- Symplectic Reduction.- Cotangent Bundle Reduction.- The Problem Setting.- Regular Symplectic Reduction by Stages.- Commuting Reduction and Semidirect Product Theory.- Regular Reduction by Stages.- Group Extensions and the Stages Hypothesis.- Magnetic Cotangent Bundle Reduction.- Stages and Coadjoint Orbits of Central Extensions.- Examples.- Stages and Semidirect Products with Cocycles.- Reduction by Stages via Symplectic Distributions.- Reduction by Stages with Topological Conditions.- Optimal Reduction and Singular Reduction by Stages, by Juan-Pablo Ortega.- The Optimal Momentum Map and Point Reduction.- Optimal Orbit Reduction.- Optimal Reduction by Stages.