5 ms·

This is called a martingale bet (https://en.m.wikipedia.org/wiki/Martingale_(betting_system) https://en.m.wikipedia.org/wiki/Martingale_(betting_system)). Doubl

by slv77 5y ago

This is called a martingale bet (https://en.m.wikipedia.org/wiki/Martingale_(betting_system) https://en.m.wikipedia.org/wiki/Martingale_(betting_system)). Doubling down on losses would be an example of a martingale bet.

jiscariot 5y ago
I think this is also a reason why tables generally have set limits.
- confidantlake 5y ago
  I don't think so. If you as the player make bets a series of bets, each with a negative expected value then your total expected value will also be negative. It doesn't matter if you double after every loss. The limits are mostly because the casino can't afford to take on a 20 billion dollar bet from someone like Bezos. Even if it has a positive expected value, they will still go broke the 49% of the time they lose it.
  - j7ake 5y ago
    The martingale strategy works because this theoretical gambler has infinitely deep pockets to withstand the losses. Setting bet limits can reduce the effectiveness of the martingale strategy.
    - confidantlake 5y ago
      I don't think it matters, even with infinite pockets. Let's say 3 is the max number of losses we will accept. 50-50 coin flip, start of betting a dollar. 7 out of 8 times we win a dollar. 1 out of 8 time we lose a dollar, double lose 2 dollars, double, lose 4 dollars quit. (7/8)(1) + (1/8)(-7) = 0 Generally: n = number of losses before quit. E(x) = (1-.5^n)(1) + (.5^n)(-2^n+1) = (1) - (1/2^n) - (2^n-1)/(2^n) = (2^n)/(2^n) - 1/(2^n) - (2^n+1) / (2^n) = (2^n -1 - 2^n + 1) / (2^n) = 0 So with a 50-50 our expected value is 0 even with an infinite bankroll. Which makes sense, there is no way to transform a series of neutral or negative expected value bets into a positive expected bet by combining them.
      - slv77 5y ago
        With an infinite bankroll there is no reason to stop at three losses. In an infinite series of fair coin flips there will be deviations in the distribution around the mean. A gambler can simply choose to stop at any point of excess “wins” as long as he isn’t stopped out due to exceeding his bankroll.
      - j7ake 5y ago
        The crazy thing about infinite pockets is that the strategy will favour the gambler even if the odds are 1-99 (or any nonzero probability of winning). Using expected value for assess winning strategies don’t work with infinite bankroll.

by slv77 5y ago

jiscariot 5y ago

I think this is also a reason why tables generally have set limits.

confidantlake 5y ago
I don't think so. If you as the player make bets a series of bets, each with a negative expected value then your total expected value will also be negative. It doesn't matter if you double after every loss. The limits are mostly because the casino can't afford to take on a 20 billion dollar bet from someone like Bezos. Even if it has a positive expected value, they will still go broke the 49% of the time they lose it.
- j7ake 5y ago
  The martingale strategy works because this theoretical gambler has infinitely deep pockets to withstand the losses. Setting bet limits can reduce the effectiveness of the martingale strategy.
  - confidantlake 5y ago
    I don't think it matters, even with infinite pockets. Let's say 3 is the max number of losses we will accept. 50-50 coin flip, start of betting a dollar. 7 out of 8 times we win a dollar. 1 out of 8 time we lose a dollar, double lose 2 dollars, double, lose 4 dollars quit. (7/8)(1) + (1/8)(-7) = 0 Generally: n = number of losses before quit. E(x) = (1-.5^n)(1) + (.5^n)(-2^n+1) = (1) - (1/2^n) - (2^n-1)/(2^n) = (2^n)/(2^n) - 1/(2^n) - (2^n+1) / (2^n) = (2^n -1 - 2^n + 1) / (2^n) = 0 So with a 50-50 our expected value is 0 even with an infinite bankroll. Which makes sense, there is no way to transform a series of neutral or negative expected value bets into a positive expected bet by combining them.
    - slv77 5y ago
      With an infinite bankroll there is no reason to stop at three losses. In an infinite series of fair coin flips there will be deviations in the distribution around the mean. A gambler can simply choose to stop at any point of excess “wins” as long as he isn’t stopped out due to exceeding his bankroll.
    - j7ake 5y ago
      The crazy thing about infinite pockets is that the strategy will favour the gambler even if the odds are 1-99 (or any nonzero probability of winning). Using expected value for assess winning strategies don’t work with infinite bankroll.