We present a mathematical analysis of a new approach to fight against computer viruses through the use of their predators. Predators are good will mobile codes which, like viruses, travel over computer networks, and replicate and multipy themselves. The only difference is that predators are specifically designed to eliminate the viruses. We model the interaction between predators and viruses by the Lotka-Volterra equations, which are widely used in mathematical biology. Using this model, we derive a method to constrain the number of predators to be as few as possible, while maintaining their power to eliminate viruses.

A simple method is presented for estimating mean delay (sojourn time in queuing terminology) of a cell-processing processor in communication switching systems by observing the actual behavior of the systems. It is shown that Little's formula leads to the estimation of the mean delay from the number of arrivals and departures. Hence, counters for these numbers are required. The method is easy to apply to real systems because measuring times of arrivals and departures, which is difficult for a call-processing processor, is not required. The accuracy of this method is evaluated for an M/G/1 queue.>