Equation of motion for interacting pulses.

We develop a systematic method of deriving the equation of motion for interacting fronts or pulses in one dimension. The theory is applicable to both dissipative and dispersive systems. In the case of the time-dependent Ginzburg-Landau equation, which is a typical example of a dissipative system, the front equation obtained is the same as has been obtained previously. The pulse interaction is also derived for the Korteweg\char21{}de Vries equation, emphasizing the difference between the cases with and without dissipative terms.