Potential symmetries

We derive and analyze the so-called potential symmetries of certain partial differential equations. At first we calculate adjoint symmetries to find integrating factors that provide the conserved currents and flux densities for the conservation law of the given partial differential equations. For some partial differential equations one is able to gain a potentialisation of the given equations by introducing a new dependent variable, the so- called potential variables. This process can in certain cases be repeated to obtain a chain of potentialisations for the same starting equation. The combined auxiliary systems associated to the chain of potentialisations give, in some cases, interesting higher degree potential symmetries for PDEs which are realized as Lie point symmetries of the auxiliary systems.Validerat; 20101217 (root