Binary equation strategy (BES) is credited to the 18th century mathematician Jean-Baptiste le Rond d'Alembert. It is a betting/trading strategy similar to a "martingale": a bettor or trader increases the amount at risk after a loss and decreases it after a gain. BES is a money-management strategy; it tells you how much to trade, not what to trade. The idea is that a win that follows a loss will recoup the loss and yield a net profit. It is based on a mathematical fallacy that a streak in one direction increases the chance that a reversal is due.