Robotics Reference
In-Depth Information
builds an evaluation function itself, and does so very quickly. Largely be-
cause of its efficient tree-searching software, the Zillions program is able
to search very deeply in comparison with its human opponents, partly
nullifying the negative aspects of having the program generate its own
evaluation function rather than having an evaluation function based on
expert human knowledge.
As the concept is further enhanced to encompass card games and
other types of game, the robots of the future might be able to announce,
for any game: “Thank you for teaching me the rules of Zappo. I under-
stand the game. Now let's play Zappo and I will crush you”.
Games with Imperfect Information and Games
with Chance
Chess, Checkers and all of the other games described earlier in this chap-
ter are categorised as being games of
perfect information
. There is nothing
unknown about them—all of the player's moves and all of his opponent's
possible replies are there for everyone to see. In games of perfect informa-
tion, a suitably deep tree search and/or a database will usually form the
most effective method of determining the best move. In contrast, some
games are characterised as presenting
imperfect information
and need a
completely different approach to programming.
Bridge
Bridge and most other card games are examples of games of imperfect
information because you do not normally know what cards your oppo-
nent(s) is (or are) holding. In Bridge there are four players, each of whom
is dealt 13 cards at the start of a hand, so although you know which
13 cards you hold, you do not know how the remaining 39 cards are
distributed.
It is not necessary to understand more than a sprinkling of the rules
of Bridge in order to follow our discussion on programming the game.
Bridge is played by four players, normally designated North, South, East
and West, who play as two partnerships (teams)—North-South are one
team and East-West the other. Each hand of Bridge (often called a
deal
)
takes place in two stages, the bidding (which is like an auction) followed
by the play of the cards.
