Computer bridge
Encyclopedia
Computer bridge is the playing of the game contract bridge
utilizing computer software. Following years of limited progress, at the end of the twentieth century the field of computer bridge has made major advances. In 1996 the American Contract Bridge League
(ACBL) established an official World Computer-Bridge Championship, to be held annually along with a major bridge event. The first championship took place in 1997 at the North American Bridge Championships in Albuquerque. Since 1999 the event has been conducted as a joint activity of the American Contract Bridge League and the World Bridge Federation
.
's book, Bridge, My Way (1992), Zia offered a £1M bet that no four-person team of his choosing would be beaten by a computer. A few years later the bridge program GIB, brainchild of American computer scientist Matthew Ginsberg, proved capable of expert declarer plays like winkle squeeze
s in play tests. In 1996, Zia withdrew his bet. Two years later, GIB became the world champion in computer bridge, and also defeated the vast majority of the world's top bridge players from the 1998 Par Contest (including Zia Mahmood). However, such a par contest measures technical bridge analysis skills only, and in 1999 Zia beat various computer programs, including GIB, in an individual round robin match.
Further progress in the field of computer bridge has resulted in stronger bridge playing programs, including Jack and Wbridge5. These programs have been ranked highly in national bridge rankings. A series of articles published in 2005 and 2006 in the Dutch bridge magazine IMP describes matches between five-time computer bridge world champion Jack and seven top Dutch pairs including a Bermuda Bowl
winner and two reigning European champions. A total of 196 boards were played. Jack defeated three out of the seven pairs (including the European champions). Overall, the program lost by a small margin (359 versus 385 imps).
and go
. Most notably, bridge is a probabilistic game: a bridge player must decide which bid to make and which card to play based on only incomplete information. At the start of a deal, the information available to each player is limited to just his/her own cards. During the bidding and the subsequent play, more information becomes available via the bidding of the other three players at the table, the cards of the partner of the declarer (the dummy) being put open on the table, and the cards played at each trick. However, it is only at the end of the deal that full information is obtained.
Today's top-level bridge programs deal with this probabilistic nature by generating many samples representing the unknown hands. Each sample is generated at random, but constrained to be compatible with all information available so far from the bidding and the play. Next, the result of different lines of play are tested against optimal defense for each sample. This testing is done utilizing a so-called double-dummy solver that via extensive search algorithms determines the optimum line of play for both parties. The line of play that generates the best score averaged over all samples is selected as the optimal play.
Efficient double-dummy solvers are key to successful bridge-playing programs. Also, as the amount of computation increases with sample size, techniques such as importance sampling
are used to generate sets of samples that are of minimum size but still representative.
, computer bridge is in its infancy. Yet, whereas computer chess has taught programmers little about building machines that offer human-like intelligence, more intuitive
and probabilistic games such as bridge
might provide a better testing ground.
The question whether bridge-playing programs will reach world-class level in the foreseeable future is not easy to answer. Computer bridge has not attracted an amount of interest anywhere near to that of computer chess. On the other hand, researchers working in the field have accomplished most of the current progress in the last decade.
Irrespective of the results of computers against humans in tournament bridge, computer bridge already has changed the analysis of the game. Commercially available double-dummy programs can solve bridge problems in which all four hands are known, typically within a second. These days, few editors of bridge books and magazines will solely rely on humans to analyse bridge problems before publications. Also, more and more bridge players and coaches utilize computer analysis in the post-mortem of a match.
Contract bridge
Contract bridge, usually known simply as bridge, is a trick-taking card game using a standard deck of 52 playing cards played by four players in two competing partnerships with partners sitting opposite each other around a small table...
utilizing computer software. Following years of limited progress, at the end of the twentieth century the field of computer bridge has made major advances. In 1996 the American Contract Bridge League
American Contract Bridge League
The American Contract Bridge League is the largest contract bridge organization in North America. It promotes the game of bridge in the United States, Mexico, Bermuda, and Canada, and is a member of the World Bridge Federation...
(ACBL) established an official World Computer-Bridge Championship, to be held annually along with a major bridge event. The first championship took place in 1997 at the North American Bridge Championships in Albuquerque. Since 1999 the event has been conducted as a joint activity of the American Contract Bridge League and the World Bridge Federation
World Bridge Federation
The World Bridge Federation is the world governing body of contract bridge. The WBF is responsible for world championship competition, most of which is conducted at a few multi-event meets on a four-year cycle...
.
World Computer-Bridge Championship
The World Computer-Bridge Championship is typically played as a round robin followed by a knock-out between the top four contestants. Winners of the annual event are:- 1997 Bridge Baron
- 1998 GIB
- 1999 GIB
- 2000 Meadowlark Bridge
- 2001 Jack
- 2002 Jack
- 2003 Jack
- 2004 Jack
- 2005 Wbridge5
- 2006 Jack
- 2007 Wbridge5
- 2008 Wbridge5
- 2009 Jack
- 2010 Jack
- 2011 Shark Bridge
Computers versus humans
In Zia MahmoodZia Mahmood
Zia Mahmood is a Pakistani professional bridge player. He is a World Bridge Federation and American Contract Bridge League Grand Life Master. He has a knack for bringing out the best in his partners and is regarded as one of the greatest players of the game...
's book, Bridge, My Way (1992), Zia offered a £1M bet that no four-person team of his choosing would be beaten by a computer. A few years later the bridge program GIB, brainchild of American computer scientist Matthew Ginsberg, proved capable of expert declarer plays like winkle squeeze
Winkle squeeze
A winkle is a rare squeeze/endplay in contract bridge in which a trick is offered to the defenders but whichever wins the trick is then endplayed...
s in play tests. In 1996, Zia withdrew his bet. Two years later, GIB became the world champion in computer bridge, and also defeated the vast majority of the world's top bridge players from the 1998 Par Contest (including Zia Mahmood). However, such a par contest measures technical bridge analysis skills only, and in 1999 Zia beat various computer programs, including GIB, in an individual round robin match.
Further progress in the field of computer bridge has resulted in stronger bridge playing programs, including Jack and Wbridge5. These programs have been ranked highly in national bridge rankings. A series of articles published in 2005 and 2006 in the Dutch bridge magazine IMP describes matches between five-time computer bridge world champion Jack and seven top Dutch pairs including a Bermuda Bowl
Bermuda Bowl
The Bermuda Bowl is a trophy awarded to the winners of the Open series in the World Team Championship in contract bridge and is named for the site of the inaugural tournament held in 1950...
winner and two reigning European champions. A total of 196 boards were played. Jack defeated three out of the seven pairs (including the European champions). Overall, the program lost by a small margin (359 versus 385 imps).
Cardplay algorithms
Bridge poses challenges to its players that are different from board games such as chessChess
Chess is a two-player board game played on a chessboard, a square-checkered board with 64 squares arranged in an eight-by-eight grid. It is one of the world's most popular games, played by millions of people worldwide at home, in clubs, online, by correspondence, and in tournaments.Each player...
and go
Go (board game)
Go , is an ancient board game for two players that originated in China more than 2,000 years ago...
. Most notably, bridge is a probabilistic game: a bridge player must decide which bid to make and which card to play based on only incomplete information. At the start of a deal, the information available to each player is limited to just his/her own cards. During the bidding and the subsequent play, more information becomes available via the bidding of the other three players at the table, the cards of the partner of the declarer (the dummy) being put open on the table, and the cards played at each trick. However, it is only at the end of the deal that full information is obtained.
Today's top-level bridge programs deal with this probabilistic nature by generating many samples representing the unknown hands. Each sample is generated at random, but constrained to be compatible with all information available so far from the bidding and the play. Next, the result of different lines of play are tested against optimal defense for each sample. This testing is done utilizing a so-called double-dummy solver that via extensive search algorithms determines the optimum line of play for both parties. The line of play that generates the best score averaged over all samples is selected as the optimal play.
Efficient double-dummy solvers are key to successful bridge-playing programs. Also, as the amount of computation increases with sample size, techniques such as importance sampling
Importance sampling
In statistics, importance sampling is a general technique for estimating properties of a particular distribution, while only having samples generated from a different distribution rather than the distribution of interest. It is related to Umbrella sampling in computational physics...
are used to generate sets of samples that are of minimum size but still representative.
The future
In comparison to computer chessComputer chess
Computer chess is computer architecture encompassing hardware and software capable of playing chess autonomously without human guidance. Computer chess acts as solo entertainment , as aids to chess analysis, for computer chess competitions, and as research to provide insights into human...
, computer bridge is in its infancy. Yet, whereas computer chess has taught programmers little about building machines that offer human-like intelligence, more intuitive
Intuition (knowledge)
Intuition is the ability to acquire knowledge without inference or the use of reason. "The word 'intuition' comes from the Latin word 'intueri', which is often roughly translated as meaning 'to look inside'’ or 'to contemplate'." Intuition provides us with beliefs that we cannot necessarily justify...
and probabilistic games such as bridge
Contract bridge
Contract bridge, usually known simply as bridge, is a trick-taking card game using a standard deck of 52 playing cards played by four players in two competing partnerships with partners sitting opposite each other around a small table...
might provide a better testing ground.
The question whether bridge-playing programs will reach world-class level in the foreseeable future is not easy to answer. Computer bridge has not attracted an amount of interest anywhere near to that of computer chess. On the other hand, researchers working in the field have accomplished most of the current progress in the last decade.
Irrespective of the results of computers against humans in tournament bridge, computer bridge already has changed the analysis of the game. Commercially available double-dummy programs can solve bridge problems in which all four hands are known, typically within a second. These days, few editors of bridge books and magazines will solely rely on humans to analyse bridge problems before publications. Also, more and more bridge players and coaches utilize computer analysis in the post-mortem of a match.