The Short Pulse Equation - a symmetry study

The classical Lie group formalism is applied to deduce classes of solutions of a special nonlinear partial differential equation, the so called Short-Pulse-Equation important in physical applications. We determine the Lie point symmetries and their algebraic properties. Similarity solutions are given as well as nonlinear transformations. In addition we discuss approximate symmetries for the first time. This analysis allows one to deduce wider classes of new unknown solutions either of practical or theoretical use.