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...