Robotics Reference
In-Depth Information
the same suit and quite a strong hand). Only one more club is needed
in the two remaining communal cards, a probability of almost forty
percent.
Poki's Betting Strategy.
Betting strategy, in other words determining
whether to fold, call, check, bet or raise in any given situation, is an
exercise in risk management.
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Poki employs different betting strategies
before the flop and after the flop. Pre-flop play in Hold'em has been ex-
tensively studied in the Poker literature, attempting to explain the correct
play in terms that can be easily understood by classifying all the initial
two-card pre-flop combinations into a number of categories. For each
class of hands a suggested betting strategy is given, based on the category,
the number of players, one's position in the betting order at the table and
the betting styles of the opponents.
After the flop Poki's basic betting strategy consists of three steps. First
it computes its effective hand strength, which is then converted into three
probability measures, after taking into account various factors such as the
program's position in the betting order. These three probabilities indicate
the frequency with which the program should fold, check/call (which are
treated as being the same), or bet/raise (also treated as being the same).
The third stage is to generate a random number between 0 and 1 and use
it to determine which of the three betting decisions should be made. For
example, if the probability of folding is 0.2, that of checking/calling is 0.5
and that of betting/raising is 0.3, then the program could simply make
its betting decisions as follows: if the random number is less than 0.2
then fold, if it lies between 0.2 and 0.7 then check or call as appropriate,
and if it is more than 0.7 then bet or raise as appropriate.
Towards World Champion.
Poki quickly became the best-known non-
commercial Texas hold'em program. In 1997 it started playing in games
without money on various Internet Poker sites and achieved an impres-
sive winning record against generally weak opposition, though the pro-
gram's own weaknesses could easily be exploited by strong players. The
program was also tested in heads-up matches
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against human oppo-
nents, including many experienced players, and again it achieved a
winning record overall. Some of the human players wrongly attributed
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As part of each betting decision a player should consider the ratio of the amount of money he
will need to wager in order to remain in contention, to how much he stands to win if he is successful,
and how this ratio compares with the program's estimate of the probability of it winning the pot.
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“Heads-up” means a two-player game, the program and only one opponent.
