D'Alembert System

The D'Alembert system is a negative progression betting strategy named after the 18th-century French mathematician Jean le Rond d'Alembert. It's based on the (incorrect) theory of 'equilibrium,' suggesting that after a loss, a win becomes more likely.

The system is simple: choose a base unit (e.g., $10). After a loss, increase your next bet by one unit. After a win, decrease by one unit. If you win as many times as you lose, you'll be up by the number of wins in units.

Example sequence: Bet $10 (lose), $20 (lose), $30 (win), $20 (win), $10. You've bet $90 total, and won $50 back from the two wins, lost $30 from the two losses. Net: -$40 to +$10 depending on order.

The D'Alembert is gentler than Martingale because bets grow linearly, not exponentially. After 10 consecutive losses, your bet is only $110 (vs $10,240 with Martingale). This means slower bankroll depletion.

However, like all betting systems, the D'Alembert does NOT change the mathematical house edge. Over the long run, you'll lose exactly the same percentage of money wagered as with flat betting.

It's a popular system because it 'feels' safer and more controlled. And it is, in terms of variance. But the expected loss remains the same. It's a smoother ride to the same destination.