Symmetries and semi-invariants in the analysis of nonlinear systems

Symmetries and Semi-invariants in the Analysis of Nonlinear Systems details the analysis of continuous- and discrete-time dynamical systems described by differential and difference equations respectively. Differential geometry provides the essential tools for the analysis, tools such as first-integrals or orbital symmetries, together with normal forms of vector fields and of maps. The use of such tools allows the solution of some important problems, studied in detail in the text, which include linearization by state immersion and the computation of nonlinear superposition formulae for nonlinear systems described by solvable Lie algebras. The theory is developed for general nonlinear systems and, in view of their importance for modeling physical systems, specialized for the class of Hamiltonian systems. By using the strong geometric structure of Hamiltonian systems, the results proposed are stated in a quite different, less complex and more easily comprehensible manner. Throughout the text the results are illustrated by many examples, some of them being physically motivated systems, so that the reader can appreciate how much insight is gained by means of these techniques. Various control systems applications of the techniques are characterized.