Butterfly
From PokerAI
This is a project started by Matrix early in 2006 in which showdown cards were used in a back-analysis to generate a probability of winning as seen by an opponent in the rounds leading to the showdown. This was then related to their observed behaviour, so that in future hands opponent behaviour could be better used to infer the strength of their hands.The iterator used to calculate win probabilities works on a weighting factor for every possible hand an opponent can hold, rather than assigned ranges in a handrank table, and the win probability for all players, rather than just the bot chair, is calculated. The algorithms used to assign opponent card weightings are extremely complex.
The major disadvantage of the Butterfly approach (apart from its appalling complexity) is that only a small proportion of hands go to showdown, and the rate of accumulation of opponent information is slow. Opponent information can be saved, and then re-loaded for future games against the same opponent.
A future extension to Butterfly will be the creation of a program which can analyse hand histories (or use PT databases) to generate the opponent profiles off-line.
