Archive forDecember, 2010

A few poker terms

Draw strength is a measure of how likely it is that your hand will become the winning hand. There are two basic approaches to computing this value. The usual method is to count your outs, and if you are sufficiently sophisticated possibly discount some of them. This generates a value somewhere in the range of [0,52], which can be normalized into a [0,1] value.

For pre flop hand strength, during the pre flop round the usual meaning of hand strength, and draw strength aren’t that useful. Without a board, the possibility of a draw is just that only a possibility. And the strength of your hand is greatly affected by the range of hands that your opponent will play. Issues of domination, implied odds, and position greatly affect how strong a hand is pre flop. Because of this, creating measures of pre flop hand strength has been a topic of great debate. Sklansky and Malmuth have developed the concept of hand groups, and Abdul Jalib created his preflop rankings through simulation.

For all-in equity, if all betting has finished, and no one can fold, this measure represents the fraction of the pot that you will win on average. This value is independent of the size of the pot, and doesn’t take into consideration any future action, bets, or folds. It does consider all draws and redraws. And if you can put your opponent on a range of hands, then you can determine whether calling an all-in raise is correct or not. In some ways, equity can be viewed as a combination of both linear hand strength and draw strength, and it’s usefulness is directly linked to situations where every hand that is the best will be shown down, and every possible draw will be drawn to.

Expected value is a well-known poker term. This is the Holy Grail of hand measures. Given a game context, the expected value (EV) of specific action represents the average profit or loss over all possible scenarios. Everything you know about a context can be used as input for this measure. Because of this, it is almost impossible to compute with absolute accuracy. But the more information that you can integrate into an estimate of EV, the more precise that measure will be. In some limited situations, very good estimates of EV can be constructed. But with a nearly boundless amount of information (including general experience, specific opponent information, and external meta-game issues) it’s impossible to create a practical definition of EV for all cases. So, just as the Holy Grail will never be found, no computation can ever give you the true EV of a situation.

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