Abstract:
In this paper, we establish a Lie type invariance condition for second order delay partial differential equations. The determining equations are obtained using Taylor’s theorem for a function of several variables. The symmetries of the wave equation with delay, its kernel and extensions of the kernel have been found. We make a complete group classification of the wave equation containing an arbitrary differentiable functional with delay, for which there is no existing literature. Further, the complete set of invariant solutions led by this classification have been found.