Invariant Discretization of Partial Differential Equations Admitting Infinite-Dimensional Symmetry Groups

Given a differential equation with infinite-dimensional symmetry pseudo-group it is shown, using an example, that it is generally not possible to construct enough joint invariants to form an invariant numerical scheme of the equation. To circumvent this problem, we propose to discretize the symmetry pseudo-group action. Using the theory of moving frames, joint invariants of the discretized action are algorithmically constructed. Computer simulations indicate that numerical schemes constructed from these joint invariants can produce better numerical results than standard schemes.