Numerical Integration of a Differential-Difference Equation with a Decreasing Time-Lag Systems in which variable time-lags are present are of common occurrence in biology. Variable flow rates are a common cause of these variable lags. At present no extensive body of knowledge exists concerning the effects which these variable lags can cause. Shown here is a method of reducing some differential-difference equations to ordinary differential equations which can then be studied numerically with ease. Subsequent study will deal with situations in which multiple-lags and lags dependent on the solution itself are present. CACM April, 1965 Bellman, R. E. Buell, J. D. Kalaba, R. E. CA650411 JB March 7, 1978 3:46 PM 1280 5 1280 1280 5 1280 1280 5 1280 1364 5 1280 1280 6 1280