Approximate Symmetry Analysis and Optimal System of Ø^4 Equation with a Small Parameter

In this paper, the problem of approximate symmetries of the nonlinear Ø^4 equation have been investigated. In order to compute the first-order approximate symmetry, we have applied the method which was proposed by Fushchich and Shtelen [3] and basically based on the expansion of the dependent variables in perturbation series. Especially, an optimal system of one dimensional subalgebras is constructed and some invariant solutions corresponding to the resulted symmetries are obtained.