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Computer chess



 
 
Computer chess is computer architecture
Computer architecture

Computer architecture in computer engineering is the conceptual design and fundamental operational structure of a computer system. It is a blueprint and functional description of requirements and design implementations for the various parts of a computer, focusing largely on the way by which the central processing unit performs internally an...
 encompassing hardware
Computer hardware

A personal computer is made up of computer hardware, multiple physical components onto which can be loaded into a multitude of software that perform the functions of the computer....
 and software
Computer software

Computer software, or just software is a general term used to describe a collection of computer programs, Algorithm and Software documentation that perform some tasks on a computer system....
 capable of play
Play

A play, or stageplay, is a form of literature written by a playwright, almost always consisting of dialogue between fictional characters, intended for theatre performance rather than Reading ....
ing chess
Chess

Chess is a recreational and competitive game played between two Player . Sometimes called Western chess or international chess to distinguish it from History of chess and other chess variants, the current form of the game emerged in Southern Europe during the second half of the 15th century after evolving from similar, much older...
 autonomously
Autonomy

Autonomy is the right to self-government. Autonomy is a concept found in moral, political, and bioethics philosophy. Within these contexts, it refers to the capacity of a Rationality individual to make an informed, un-coerced decision....
 without human
Human

A human being, also human or man, is a member of a species of bipedalism primates in the family Hominidae . Mitochondrial DNA evidence indicates that modern humans originated in east Africa about 200,000 years ago....
 guidance
Guidance

Guidance may refer to:*Guidance *Guidance system*Guidance Solutions, an eCommerce development company*"Guidance", an episode of Death Note...
.

idea of creating a chess
Chess

Chess is a recreational and competitive game played between two Player . Sometimes called Western chess or international chess to distinguish it from History of chess and other chess variants, the current form of the game emerged in Southern Europe during the second half of the 15th century after evolving from similar, much older...
-playing machine dates back to the eighteenth century. Around 1769, the chess playing automaton
Automaton

An automaton is a self-operating machine. The word is sometimes used to describe a robot, more specifically an autonomous robot....
 called The Turk
The Turk

The Turk or Automaton Chess Player was a chess-playing artificial intelligence constructed in the late 18th century, and exhibited from 1770 for over 84 years, by various owners, as an automaton but later explained in the early 1820's as an elaborate hoax ....
 became famous before being exposed as a hoax
Hoax

A hoax is a deliberate attempt to dupe, deceive or deception an audience into believing, or accepting, that something is real, when in fact it is not; or that something is true, when in fact it is false....
.






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Rs Chess Computer
Computer chess is computer architecture
Computer architecture

Computer architecture in computer engineering is the conceptual design and fundamental operational structure of a computer system. It is a blueprint and functional description of requirements and design implementations for the various parts of a computer, focusing largely on the way by which the central processing unit performs internally an...
 encompassing hardware
Computer hardware

A personal computer is made up of computer hardware, multiple physical components onto which can be loaded into a multitude of software that perform the functions of the computer....
 and software
Computer software

Computer software, or just software is a general term used to describe a collection of computer programs, Algorithm and Software documentation that perform some tasks on a computer system....
 capable of play
Play

A play, or stageplay, is a form of literature written by a playwright, almost always consisting of dialogue between fictional characters, intended for theatre performance rather than Reading ....
ing chess
Chess

Chess is a recreational and competitive game played between two Player . Sometimes called Western chess or international chess to distinguish it from History of chess and other chess variants, the current form of the game emerged in Southern Europe during the second half of the 15th century after evolving from similar, much older...
 autonomously
Autonomy

Autonomy is the right to self-government. Autonomy is a concept found in moral, political, and bioethics philosophy. Within these contexts, it refers to the capacity of a Rationality individual to make an informed, un-coerced decision....
 without human
Human

A human being, also human or man, is a member of a species of bipedalism primates in the family Hominidae . Mitochondrial DNA evidence indicates that modern humans originated in east Africa about 200,000 years ago....
 guidance
Guidance

Guidance may refer to:*Guidance *Guidance system*Guidance Solutions, an eCommerce development company*"Guidance", an episode of Death Note...
.

Background

The idea of creating a chess
Chess

Chess is a recreational and competitive game played between two Player . Sometimes called Western chess or international chess to distinguish it from History of chess and other chess variants, the current form of the game emerged in Southern Europe during the second half of the 15th century after evolving from similar, much older...
-playing machine dates back to the eighteenth century. Around 1769, the chess playing automaton
Automaton

An automaton is a self-operating machine. The word is sometimes used to describe a robot, more specifically an autonomous robot....
 called The Turk
The Turk

The Turk or Automaton Chess Player was a chess-playing artificial intelligence constructed in the late 18th century, and exhibited from 1770 for over 84 years, by various owners, as an automaton but later explained in the early 1820's as an elaborate hoax ....
 became famous before being exposed as a hoax
Hoax

A hoax is a deliberate attempt to dupe, deceive or deception an audience into believing, or accepting, that something is real, when in fact it is not; or that something is true, when in fact it is false....
. Before the development of digital computing, serious trials based on automata such as El Ajedrecista
El Ajedrecista

El Ajedrecista was an automaton built in 1912 by Leonardo Torres y Quevedo. El Ajedrecista made a public debut during the Paris World Fair of 1914, creating great excitement at the time....
 of 1912, were too complex and limited to be useful for playing full games of chess. The field of mechanical chess research languished until the advent of the digital computer in the 1950s. Since then, chess enthusiasts and computer engineers have built, with increasing degrees of seriousness and success, chess-playing machines and computer programs.

Human-computer chess matches
Human-computer chess matches

This article documents the progress of significant Human-computer chess matches.Computer chess were first able to beat strong chess players in the late 1980s....
 showed the best computer systems overtaking human chess champions in the late 1990's. For the 40 years prior to that, the trend had been that the best machines gained about 40 points per year in the ELO ranking while the best humans only gained roughly 2 points per year. There was speculation that audience interest in human-computer chess competition would wane as a result of matches such as the 2006 Kramnik-Deep Fritz match in which Kramnik lost the match 4 games to 2. The highest rating obtained by a computer in human competition was Deep Thought
Deep Thought (chess computer)

Deep Thought was a computer designed to play chess. Deep Thought was initially developed at Carnegie Mellon University and later at IBM. It was second in the line of chess computers developed by Feng-hsiung Hsu, starting with ChipTest and culminating in IBM Deep Blue....
's USCF rating of 2551 in 1988 and FIDE no longer accepts human-computer results in their rating lists. Specialized machine-only ELO pools have been created for rating machines but such numbers, while similar in appearance, should not be directly compared. A recent top chess engine, Rybka
Rybka

Rybka is a computer chess engine designed by International Master Vasik Rajlich and Grandmaster Larry Kaufman. , Rybka is top-rated in all notable chess engine rating lists and has won many official Computer Chess Tournaments including the 2007 and 2008 World Computer Chess Championships....
 has an estimated ELO rating at SSDF
SSDF

SSDF can refer to:*Swedish Chess Computer Association*Somali Salvation Democratic Front...
 on an up-to-date PC of about 3200.
Chessmaster 10th Edition2 Edited
Chess-playing computers are now accessible to the average consumer. There are many chess engines such as Crafty
Crafty

Crafty is a chess program written by University of Alabama at Birmingham professor Robert Hyatt. It is directly derived from Cray Blitz, winner of the 1983 and 1986 World Computer Chess Championships....
, Fruit and GNU Chess
GNU Chess

GNU Chess is a computer program for playing chess. GNU Chess is one of the oldest computer chess programs for Unix-based computers and has been ported to several other platforms....
 that can be downloaded from the Internet
Internet

The Internet is a global network of interconnected computers, enabling users to share information along multiple channels. Typically, a computer that connects to the Internet can access information from a vast array of available server and other computers by moving information from them to the computer's local memory....
 for free, and play a game that when run on any up-to-date personal computer
Personal computer

A personal computer is any general-purpose computer whose original sales price, size, and capabilities make it useful for individuals, and which is intended to be operated directly by an end user, with no intervening computer operator....
, can defeat most master players under tournament conditions. Top commercial programs like Shredder
Shredder (chess)

Shredder is a commercial chess program developed in Germany by Stefan Meyer-Kahlen in 1993. Shredder won the World Microcomputer Chess Championship in 1996 and 2000, the World Computer Chess Championship in 1999 and 2003, and the World Computer Speed Chess Championship in 2002, 2003, 2004, 2005, and 2007....
 or Fritz
Fritz (chess)

Fritz is a Germany computer chess developed by Frans Morsch and Mathias Feist and published by ChessBase. There is also a version called Deep Fritz that is designed for multi-processing....
 have surpassed even world champion caliber players at blitz
Blitz chess

Fast chess, also known as blitz chess, sudden death, speed chess, bullet chess and rapid chess, is a type of chess game in which each side is given less time to make their moves than under the normal tournament time controls of 60?180 minutes per player....
 and short time control
Time control

A time control is a mechanism in the tournament play of almost all two-player board games so that each round of the match can finish in a timely way and the tournament can proceed....
s. , Rybka
Rybka

Rybka is a computer chess engine designed by International Master Vasik Rajlich and Grandmaster Larry Kaufman. , Rybka is top-rated in all notable chess engine rating lists and has won many official Computer Chess Tournaments including the 2007 and 2008 World Computer Chess Championships....
 is top-rated in CCRL, CEGT, CSS, SSDF
Swedish Chess Computer Association

The Swedish Chess Computer Association is an organization that tests computer chess software by playing chess programs against one another and producing a rating list....
, and WBEC rating lists and has won many recent official computer chess tournaments such as CCT 8 and 9, 2006 Dutch Open Computer Championship, the 16th IPCCC, and the 15th World Computer Chess Championship
World Computer Chess Championship

World Computer Chess Championship is an annual event where computer chess chess engines compete against each other. The event is organized by the International Computer Games Association....
.

Motivation

The prime motivations for computerized chess playing have been solo entertainment (allowing players to practice and to amuse themselves when no human opponents are available), as aids to chess analysis, for computer chess competitions, and as research to provide insights into human cognition
Cognition

Cognition is the science term for "the process of thought."Its usage varies in different ways in accord with different disciplines: For example, in psychology and cognitive science it refers to an information processing view of an individual's psychological Functionalism s....
. For the first two purposes, computer chess has been a phenomenal success — going from the earliest real attempts to programs which challenge the best human players took less than fifty years.

Brute force versus selective search

The first paper on the subject was by Claude Shannon
Claude Elwood Shannon

Claude Elwood Shannon , an United States of America electronic engineer and mathematician, is known as "the father of information theory".Shannon is famous for having founded information theory with one landmark paper published in 1948....
 — published in 1950 before anyone had programmed a computer to play chess. He successfully predicted the two main possible search strategies which would be used, which he labeled "Type A" and "Type B" .

Type A programs would use a "brute force
Brute-force search

In computer science, brute-force search or exhaustive search, also known as generate and test, is a trivial but very general problem-solving technique that consists of systematically enumerating all possible candidates for the solution and checking whether each candidate satisfies the problem's statement....
" approach, examining every possible position for a fixed number of moves using the minimax algorithm
Minimax

Minimax is a decision rule used in decision theory, game theory, statistics and philosophy for minimizing the maximum possible loss function....
. Shannon believed this would be impractical for two reasons.

First, with approximately thirty moves possible in a typical real-life position, he expected that searching the approximately 109 positions involved in looking three moves ahead for both sides (six plies
Ply (game theory)

In two-player sequential games, a ply refers to one turn taken by one of the players. The word is used to clarify what is meant when one might otherwise say "turn"....
) would take about sixteen minutes, even in the "very optimistic" case that the chess computer evaluated a million positions every second. (It took about forty years to achieve this speed.)

Second, it ignored the problem of quiescence, trying to only evaluate a position that is at the end of an exchange of pieces or other important sequence of moves ('lines'). He expected that adapting type A to cope with this would greatly increase the number of positions needing to be looked at and slow the program down still further.

Instead of wasting processing power examining bad or trivial moves, Shannon suggested that "type B" programs would use two improvements:
  1. Employ a quiescence search
    Quiescence search

    Quiescence search is an algorithm typically used to evaluate minimax game trees in Games of skill#Games of mental skill-playing computer programs....
    .
  2. Only look at a few good moves for each position.
This would enable them to look further ahead ('deeper') at the most significant lines in a reasonable time. The test of time has borne out the first approach; all modern programs employ a terminal quiescence search before evaluating positions. The second approach (now called forward pruning) has been dropped in favor of search extensions.

Adriaan de Groot
Adriaan de Groot

Adrianus Dingeman de Groot was a Netherlands chess master and psychologist, who conducted some of the most famous chess experiments of all time in the 1940s-60....
 interviewed a number of chess players of varying strengths, and concluded that both masters
Chess master

A chess master is a chess player of such skill that he/she can usually beat chess experts, who themselves typically can nearly always prevail against most amateurs....
 and beginners look at around forty to fifty positions before deciding which move to play. What makes the former much better players is that they use pattern recognition
Pattern recognition

Pattern recognition is a sub-topic of machine learning. It is "the act of taking in raw data and taking an action based on the Category of the data"....
 skills built from experience. This enables them to examine some lines in much greater depth than others by simply not considering moves they can assume to be poor.

More evidence for this being the case is the way that good human players find it much easier to recall positions from genuine chess games, breaking them down into a small number of recognizable sub-positions, rather than completely random arrangements of the same pieces. In contrast, poor players have the same level of recall for both.

The problem with type B is that it relies on the program being able to decide which moves are good enough to be worthy of consideration ('plausible') in any given position and this proved to be a much harder problem to solve than speeding up type A searches with superior hardware and search extension techniques.

One of the few chess grandmasters to devote himself seriously to computer chess was former World Chess Champion Mikhail Botvinnik
Mikhail Botvinnik

Mikhail Moiseyevich Botvinnik was a Russian International Grandmaster and long-time World Chess Championship. As an Electrical engineering, he was one of the very few famous chess players who achieved distinction in another career while playing top-class competitive chess....
, who wrote several works on the subject. He also held a doctorate in Electrical engineering. Working with relatively primitive hardware available in the Soviet Union
Soviet Union

The Union of Soviet Socialist Republics was a Constitution of the Soviet Union socialist state that existed in Eurasia from 1922 to 1991.The name is a translation of the , romanization of Russian Soyuz Sovetskikh Sotsialisticheskikh Respublik, abbreviated ????, SSSR....
 in the early 1960s, Botvinnik had no choice but to investigate software move selection techniques; at the time only the most powerful computers could achieve much beyond a three-ply
Ply (game theory)

In two-player sequential games, a ply refers to one turn taken by one of the players. The word is used to clarify what is meant when one might otherwise say "turn"....
 full-width search, and Botvinnik had no such machines. In 1965 Botvinnik was a consultant to the ITEP team in a US-Soviet computer chess match (see Kotok-McCarthy
Kotok-McCarthy

Kotok-McCarthy also known as was the first computer program to play chess convincingly. It is also remembered because it played in and lost the first chess match between two computer programs....
).

One developmental milestone occurred when the team from Northwestern University
Northwestern University

Northwestern University is a non-sectarian private university research university located in Evanston, Illinois and downtown Chicago, Illinois, United States....
, which was responsible for the Chess
Chess (Northwestern University)

Chess was a pioneering chess engine from the 1970s, authored by Larry Atkin and David Slate at Northwestern University. Chess ran on Control Data Corporation's line of supercomputers....
 series of programs and won the first three ACM
Association for Computing Machinery

The Association for Computing Machinery, or ACM, was founded in 1947 as the world's first scientific and educational computing society. Its membership was approximately 83,000 as of 2007....
 Computer Chess Championships
World Computer Chess Championship

World Computer Chess Championship is an annual event where computer chess chess engines compete against each other. The event is organized by the International Computer Games Association....
 (1970-72), abandoned type B searching in 1973. The resulting program, Chess 4.0, won that year's championship and its successors went on to come in second in both the 1974 ACM Championship and that year's inaugural World Computer Chess Championship
World Computer Chess Championship

World Computer Chess Championship is an annual event where computer chess chess engines compete against each other. The event is organized by the International Computer Games Association....
, before winning the ACM Championship again in 1975, 1976 and 1977.

One reason they gave for the switch was that they found it less stressful during competition, because it was difficult to anticipate which moves their type B programs would play, and why. They also reported that type A was much easier to debug in the four months they had available and turned out to be just as fast: in the time it used to take to decide which moves were worthy of being searched, it was possible just to search all of them.

In fact, Chess 4.0 set the paradigm that was and still is followed essentially by all modern Chess programs today. Chess 4.0 type programs won out for the simple reason that their programs simply played better chess. Such programs did not try to mimic human thought processes, but relied on full width alpha-beta
Alpha-beta pruning

Alpha-beta pruning is a search algorithm which seeks to reduce the number of nodes that are evaluated in the game tree by the Minimax#Minimax algorithm with alternate moves....
 and negascout
Negascout

NegaScout or Principal Variation Search is a negamax algorithm that can be faster than alpha-beta pruning. Like alpha-beta pruning, NegaScout is a directional search algorithm for computing the minimax value of a node in a tree....
 searches. Most such programs (including all modern programs today) also included a fairly limited selective part of the search based around quiescence searches, and usually extensions and pruning (particularly null move pruning from the 1990s onwards) which were triggered based on certain conditions in an attempt to weed out or reduce obviously bad moves (history moves) or to investigate interesting nodes (e.g. check extensions, passed pawn
Passed pawn

In chess, a passed pawn is a pawn with no opposing pawns to prevent it from advancing to the eighth chess terminology#Rank, i.e. there are no opposing pawns in front of it on the same chess terminology#File nor on an adjacent file....
s on seventh rank, etc). Extension and pruning triggers have to be used very carefully however. Over extend and the program wastes too much time looking at uninteresting positions. If too much is pruned, there is a risk cutting out interesting nodes. Chess programs differ in terms of how and what types of pruning and extension rules are included as well as in the evaluation function. Some programs are believed to be more selective than others (for example Deep Blue was known to be less selective than most commercial programs because they could afford to do more complete full width searches), but all have a base full width search as a foundation and all have some selective components (Q-search, pruning/extensions).

Though such additions meant that the program did not truly examine every node within its search depth (so it would not be truly brute force in that sense), the rare mistakes due to these selective search was found to be worth the extra time it saved because it could search deeper. In that way Chess programs can get the best of both worlds.

Furthermore, technological advances by orders of magnitude in processing power have made the brute force approach far more incisive than was the case in the early years. The result is that a very solid, tactical AI player aided by some limited positional knowledge built in by the evaluation function and pruning/extension rules began to match the best players in the world. It turned out to produce excellent results, at least in the field of chess, to let computers do what they do best (calculate) rather than coax them into imitating human thought processes and knowledge. In 1997 Deep Blue defeated World Champion Garry Kasparov
Garry Kasparov

Garry Kasparov is a Russian former World Chess Champion, regarded by many as Methods for comparing top chess players throughout history. He is also a writer and political activist....
, marking the first time a computer has defeated a reigning world chess champion in standard time control.

Computers versus humans

For a time in the 1970s and 1980s it was unclear whether any Chess program would ever be able to defeat the expertise of top humans. In 1968, International Master
International Master

The title International Master is awarded to outstanding chess players by the world chess organization F?d?ration Internationale des ?checs. The title is open to both men and women....
 David Levy
David Levy (chess player)

David Neil Lawrence Levy , is a Scotland International Master of chess, a businessman noted for his involvement with computer chess, and the founder of the Computer Olympiads and the Mind Sports Olympiads....
 made a famous bet that no chess computer would be able to beat him within ten years. He won his bet in 1978 by beating Chess 4.7
Chess (Northwestern University)

Chess was a pioneering chess engine from the 1970s, authored by Larry Atkin and David Slate at Northwestern University. Chess ran on Control Data Corporation's line of supercomputers....
 (the strongest computer at the time), but acknowledged then that it would not be long before he would be surpassed. In 1989, Levy was defeated by the computer Deep Thought
Deep Thought (chess computer)

Deep Thought was a computer designed to play chess. Deep Thought was initially developed at Carnegie Mellon University and later at IBM. It was second in the line of chess computers developed by Feng-hsiung Hsu, starting with ChipTest and culminating in IBM Deep Blue....
 in an exhibition match.

Deep Thought, however, was still considerably below World Championship Level, as the then reigning world champion Garry Kasparov
Garry Kasparov

Garry Kasparov is a Russian former World Chess Champion, regarded by many as Methods for comparing top chess players throughout history. He is also a writer and political activist....
 demonstrated in two sterling wins in 1989. It wasn't until a 1996 match with IBM's Deep Blue that Kasparov lost his first game to a computer at tournament time controls in Deep Blue - Kasparov, 1996, Game 1
Deep Blue - Kasparov, 1996, Game 1

Deep Blue ? Kasparov, 1996, Game 1 is a famous chess game in which a computer played against a human being. It was the first game played in the 1996 Deep Blue versus Garry Kasparov match, and the first time that a Computer chess defeated a reigning World Chess Championship under normal chess tournament conditions ....
. This game was, in fact, the first time a reigning world champion had lost to a computer using regular time controls. However, Kasparov regrouped to win three and draw
Draw (chess)

In chess, a draw is one of the possible outcomes of a game, the others being a win for White and a win for Black . Traditionally, in tournaments a draw is worth a half point to each player, while a win is worth one point to the victor and none to the loser....
 two of the remaining five games of the match, for a convincing victory.

In May 1997, an updated version of Deep Blue defeated Kasparov 3½-2½ in a return match. A documentary mainly about the confrontation was made in 2003, titled Game Over: Kasparov and the Machine
Game Over: Kasparov and the Machine

Game Over: Kasparov and the Machine is a 2003 in film documentary film by Vikram Jayanti about the match between Garry Kasparov, the highest rated chess player in history and the World Chess Championship for 15 years , and IBM Deep Blue, a chess-playing computer created by IBM....
. IBM keeps a web site of .

With increasing processing power, Chess programs running on commercially available workstations began to rival top flight players. In 1998, Rebel 10
REBEL (chess)

REBEL was a world champion chess program developed by Ed Schr?der. Development of REBEL started in 1980 on a TRS-80, and it was ported many times to dedicated hardware and the fastest microprocessors of the day:...
 defeated Viswanathan Anand
Viswanathan Anand

Viswanathan Anand is an Indian chess International Grandmaster and the current World Chess Championship.Anand won the FIDE World Chess Championship in 2000, at a time when the world title was split....
 who at the time was ranked second in the world, by a score of 5-3. However most of those games were not played at normal time controls. Out of the eight games, four were blitz
Blitz chess

Fast chess, also known as blitz chess, sudden death, speed chess, bullet chess and rapid chess, is a type of chess game in which each side is given less time to make their moves than under the normal tournament time controls of 60?180 minutes per player....
 games (five minutes plus five seconds Fischer delay (see time control
Time control

A time control is a mechanism in the tournament play of almost all two-player board games so that each round of the match can finish in a timely way and the tournament can proceed....
) for each move) these Rebel won 3-1. Then two were semi-blitz games (fifteen minutes for each side) which Rebel won as well (1½-½). Finally two games were played as regular tournament games (forty moves in two hours, one hour sudden death) here it was Anand who won ½-1½ . At least in fast games, computers played better than humans but at classical time controls - at which a player's rating is determined - the advantage was not so clear.

In the early 2000s, commercially available programs such as Junior and Fritz
Fritz (chess)

Fritz is a Germany computer chess developed by Frans Morsch and Mathias Feist and published by ChessBase. There is also a version called Deep Fritz that is designed for multi-processing....
 were able to draw matches against former world champion Garry Kasparov
Garry Kasparov

Garry Kasparov is a Russian former World Chess Champion, regarded by many as Methods for comparing top chess players throughout history. He is also a writer and political activist....
 and "classical" world champion Vladimir Kramnik
Vladimir Kramnik

Vladimir Borisovich Kramnik is a Russian chess International Grandmaster. He was Classical World Chess Championship 2000 from 2000 to 2006, and undisputed World Chess Champion from 2006 to 2007....
.

In October 2002, Vladimir Kramnik
Vladimir Kramnik

Vladimir Borisovich Kramnik is a Russian chess International Grandmaster. He was Classical World Chess Championship 2000 from 2000 to 2006, and undisputed World Chess Champion from 2006 to 2007....
 and Deep Fritz competed in the eight-game Brains in Bahrain
Brains in Bahrain

Brains in Bahrain was an eight-game chess match between World Chess Champion Vladimir Kramnik and the computer chess Deep Fritz 7, held in October 2002....
 match, which ended in a draw. Kramnik won games 2 and 3 by "conventional" anti-computer tactics
Anti-computer tactics

Anti-computer tactics are a style of play used by humans to beat strong computer opponents at various games, especially in board games such as chess....
 - play conservatively for a long-term advantage the computer is not able to see in its game tree search. Fritz, however, won game 5 after a severe blunder by Kramnik. Game 6 was described by the tournament commentators as "spectacular." Kramnik, in a better position in the early middlegame, tried a piece sacrifice to achieve a strong tactical attack, a strategy known to be highly risky against computers who are at their strongest defending against such attacks. True to form, Fritz found a watertight defense and Kramnik's attack petered out leaving him in a bad position. Kramnik resigned the game, believing the position lost. However, post-game human and computer analysis has shown that the Fritz program was unlikely to have been able to force a win and Kramnik effectively sacrificed a drawn position. The final two games were draws. Given the circumstances, most commentators still rate Kramnik the stronger player in the match.

In January 2003, Garry Kasparov
Garry Kasparov

Garry Kasparov is a Russian former World Chess Champion, regarded by many as Methods for comparing top chess players throughout history. He is also a writer and political activist....
 played Junior, another chess computer program, in New York
New York

The State of New York is a U.S. state in the Mid-Atlantic States and Northeastern United States regions of the United States and is the nation's List of U.S....
. The match ended 3-3.

In November 2003, Garry Kasparov
Garry Kasparov

Garry Kasparov is a Russian former World Chess Champion, regarded by many as Methods for comparing top chess players throughout history. He is also a writer and political activist....
 played X3D Fritz
X3D Fritz

X3D Fritz was a version of the Fritz , which in November 2003 played a four game Human-computer chess match against world number one International Grandmaster Garry Kasparov....
. The match ended 2-2.

In 2005, Hydra
Hydra (chess)

Hydra is a chess machine, designed by a team with Christian Donninger, Dr. Ulf Lorenz, International Grandmaster Christopher Lutz and Muhammad Nasir Ali....
, a dedicated chess computer with custom hardware and sixty-four processors and also winner of the 14th IPCCC in 2005, defeated seventh-ranked Michael Adams
Michael Adams

Michael Adams is a United Kingdom Grandmaster of chess. His highest ranking is world number 4, achieved several times from October 2000 to October 2002....
 5½-½ in a six-game match (though Adams' preparation was far less thorough than Kramnik's for the 2002 series). Some commentators believe that Hydra will ultimately prove clearly superior to the very best human players, or if not its direct successor will. Hydra went on to beat Grandmaster players in odds matches.

In November-December 2006, World Champion Vladimir Kramnik
Vladimir Kramnik

Vladimir Borisovich Kramnik is a Russian chess International Grandmaster. He was Classical World Chess Championship 2000 from 2000 to 2006, and undisputed World Chess Champion from 2006 to 2007....
 played Deep Fritz. This time the computer won, the match ended 2-4. Kramnik was able to view the computer's opening book. In the first five games Kramnik steered the game into a typical "anti-computer" positional contest. He lost one game (overlooking a mate in one), and drew the next four. In the final game, in an attempt to draw the match, Kramnik played the more aggressive Sicilian Defence
Sicilian Defence

The Sicilian Defence is a chess chess opening that begins with the moves:The Sicilian is the most popular and best-scoring response to White's first move 1.e4....
 and was crushed.

There was speculation that interest in human-computer chess competition would plummet as a result of the 2006 Kramnik-Deep Fritz match. According to McGill University computer science professor Monty Newborn, for example, "the science is done".

Endgame tablebases


Computers have been used to analyze some chess endgame positions completely. Such endgame databases are generated in advance using a form of retrograde analysis
Retrograde analysis

Retrograde analysis is a technique employed by chess problem solvers to determine which moves were played leading up to a given position. While this technique is rarely needed for solving ordinary chess problems, there is a whole sub-genre of chess problems in which it is an important part; such problems are known as retros....
, starting with positions where the final result is known (e.g. where one side has been mated) and seeing which other positions are one move away from them, then which are one move from those etc. Ken Thompson, perhaps better known as the key designer of the UNIX
Unix

Unix is a computer operating system originally developed in 1969 by a group of American Telephone & Telegraph employees at Bell Labs, including Ken Thompson , Dennis Ritchie, Douglas McIlroy, and Joe Ossanna....
 operating system
Operating system

An operating system is an interface between hardware and applications; it is responsible for the management and coordination of activities and the sharing of the limited resources of the computer....
, was a pioneer in this area.

Endgame play had long been one of the great weaknesses of chess programs because of the depth of search needed, with some otherwise master-level programs being unable to win in positions that even intermediate human players would be able to force a win.

The results of the computer analysis sometimes surprised people. In 1977 Thompson's Belle chess machine used the endgame tablebase for a king
King (chess)

In chess, the King is the most important chess piece. The object of the game is to trap the opponent's king so that he would not be able to avoid capture ....
 and rook
Rook (chess)

A rook is a chess piece in the strategy board game of chess. In the past the piece was called the castle, tower, marquess, rector, and comes , and non-players still often call it a "castle"....
 against king and queen
Queen (chess)

The queen is the most powerful chess piece in the game of chess. Each player starts the game with one queen, placed in the middle of their first rank next to their King ....
 and was able to draw that theoretically lost ending against several masters (see Philidor position#Queen versus rook
Philidor position

The Philidor position usually refers to an important chess Chess endgame which illustrates a Draw technique when the defender has a king and rook versus a king, rook, and pawn ....
). This was despite not following the usual strategy to delay defeat by keeping the defending king and rook close together for as long as possible. Asked to explain the reasons behind some of the program's moves, Thompson was unable to do so beyond saying the program's database simply evaluated its moves as best it could.

Most grandmasters
International Grandmaster

The title Grandmaster is awarded to extremely strong chess masters by the world chess organization FIDE. Apart from "World Chess Championship", Grandmaster is the highest title a chess player can attain....
 declined to play against the computer in the queen versus rook endgame, but Walter Browne
Walter Browne

Walter Shawn Browne is an Australian and United States chess Grandmaster and poker player. Browne has won the U.S. Chess Championship six times....
 accepted the challenge. A queen versus rook position was set up in which the queen can win in thirty moves, with perfect play. Browne was allowed 2½ hours to play fifty moves, otherwise a draw would be claimed under the fifty-move rule. After forty-five moves, Browne agreed to a draw, being unable to force checkmate or win the rook within the next five moves. In the final position, Browne was still seventeen moves away from checkmate, but not quite that far away from winning the rook. Browne studied the endgame, and played the computer again a week later in a different position in which the queen can win in thirty moves. This time, he captured the rook on the fiftieth move, giving him a winning position , .

Other positions, long believed to be won, turned out to take more moves against perfect play to actually win than were allowed by chess's fifty-move rule. As a consequence, for some years the official laws of chess were changed to extend the number of moves allowed in these endings. After a while, the law reverted back to fifty moves in all positions — more such positions were discovered, complicating the rule still further, and it made no difference in human play, as they could not play the positions perfectly.

Over the years, other endgame database
Database

A database is a structured collection of records or data that is stored in a computer system. The structure is achieved by organizing the data according to a database model....
 formats have been released including the Edward Tablebases, the De Koning Endgame Database (released in 2002) and the Nalimov
Eugene Nalimov

Eugene Nalimov is a chess programmer and Microsoft employee.Starting in 1998, he wrote a tablebase generator which included many different endgames....
 Endgame Tablebases which is the current standard supported by most chess programs such as Rybka
Rybka

Rybka is a computer chess engine designed by International Master Vasik Rajlich and Grandmaster Larry Kaufman. , Rybka is top-rated in all notable chess engine rating lists and has won many official Computer Chess Tournaments including the 2007 and 2008 World Computer Chess Championships....
, Shredder
Shredder (chess)

Shredder is a commercial chess program developed in Germany by Stefan Meyer-Kahlen in 1993. Shredder won the World Microcomputer Chess Championship in 1996 and 2000, the World Computer Chess Championship in 1999 and 2003, and the World Computer Speed Chess Championship in 2002, 2003, 2004, 2005, and 2007....
 or Fritz
Fritz (chess)

Fritz is a Germany computer chess developed by Frans Morsch and Mathias Feist and published by ChessBase. There is also a version called Deep Fritz that is designed for multi-processing....
. All endgames with five or fewer pieces have been analyzed completely. Of endgames with six pieces all positions have been analyzed except for positions with five pieces against a lone king. Some seven-piece endgames, have been analyzed by Marc Bourzutschky and Yakov Konoval. In all of these endgame databases it is assumed that castling is no longer possible.

The databases are generated by storing in memory the values of positions which have been encountered so far, and using these results to lop off the ends of the search trees if they arise again. Although the number of possible games after a number of moves rises exponentially with the number of moves, the number of possible positions with a few pieces is exponential only in the number of pieces — and effectively limited however many end game moves are searched. The simple expediency of remembering the value of all previously reached positions means that the limiting factor in solving end games is simply the amount of memory available in the computer. While computer memory sizes are increasing exponentially, there is no reason why end games of increasing complexity should not continue to be solved.

A computer using these databases will, upon reaching a position in them, be able to play perfectly, and immediately determine whether the position is a win, loss or draw, plus the fastest or longest way of getting to that result. Knowledge of whether a position is a win, loss or draw is also helpful in advance since this can help the computer avoid or head towards such positions depending on the situation.

Endgame databases featured prominently in 1999, when Kasparov played an exhibition match on the Internet against the Rest of the World
Kasparov versus The World

Kasparov versus The World was a game of chess played in 1999 over the Internet. Conducting the white pieces, Garry Kasparov faced the rest of the world in consultation, with the World Team moves to be decided by plurality vote....
. A seven piece Queen
Queen (chess)

The queen is the most powerful chess piece in the game of chess. Each player starts the game with one queen, placed in the middle of their first rank next to their King ....
 and pawn
Pawn (chess)

The pawn is the weakest and most numerous chess piece in the game of chess, representing infantry, or more particularly armed peasants or pikemen....
 endgame was reached with the World Team fighting to salvage a draw. Eugene Nalimov
Eugene Nalimov

Eugene Nalimov is a chess programmer and Microsoft employee.Starting in 1998, he wrote a tablebase generator which included many different endgames....
 helped by generating the six piece ending tablebase where both sides had two Queens which was used heavily to aid analysis by both sides.

Implementation issues

The developers of a chess-playing computer system must decide on a number of fundamental implementation issues. These include:
  • Board representation — how a single position is represented in data structures,
  • Search techniques — how to identify the possible moves and select the most promising ones for further examination,
  • Leaf evaluation — how to evaluate the value of a board position, if no further search will be done from that position.


Implementors also need to decide if they will use endgame databases or other optimizations, and often implement common de facto chess standards.

Board representations

The data structure used to represent each chess position is key to the performance of move generation and position evaluation. Methods include pieces stored in an array ("mailbox" and "0x88"), piece positions stored in a list ("piece list"), collections of bit-sets for piece locations ("bitboard
Bitboard

A bitboard is a data structure commonly used in Game AI board games....
s"), and huffman coded
Huffman coding

In computer science and information theory, Huffman coding is an entropy encoding algorithm used for lossless data compression. The term refers to the use of a variable-length code table for encoding a source symbol where the variable-length code table has been derived in a particular way based on the estimated probability of occurrence for...
 positions for compact long-term storage.

Search techniques

Computer chess programs consider chess moves as a game tree
Game tree

In combinatorial game theory, a game tree is a directed graph whose node s are positions in a game and whose edge s are moves. The complete game tree for a game is the game tree starting at the initial position and containing all possible moves from each position....
. In theory, they examine all moves, then all counter-moves to those moves, then all moves countering them, and so on, where each individual move by one player is called a "ply"
Ply (game theory)

In two-player sequential games, a ply refers to one turn taken by one of the players. The word is used to clarify what is meant when one might otherwise say "turn"....
. This evaluation continues until it reaches a certain maximum search depth or the program determines that a final "leaf" position has been reached (e.g. checkmate).

A naive implementation of this approach, however, could only search to a small depth in a practical amount of time, so various methods have been devised to greatly speed the search for good moves.

For more information, see:

  • Minimax
    Minimax

    Minimax is a decision rule used in decision theory, game theory, statistics and philosophy for minimizing the maximum possible loss function....
     algorithm
  • Alpha-beta pruning
    Alpha-beta pruning

    Alpha-beta pruning is a search algorithm which seeks to reduce the number of nodes that are evaluated in the game tree by the Minimax#Minimax algorithm with alternate moves....
  • Killer heuristic
    Killer heuristic

    In competitive two-player games, the killer heuristic is a technique for improving the efficiency of alpha-beta pruning, which in turn improves the efficiency of the minimax algorithm....
  • Iterative deepening depth-first search
    Iterative deepening depth-first search

    Iterative deepening depth-first search is a state space search strategy in which a depth-limited search is run repeatedly, increasing the depth limit with each iteration until it reaches , the depth of the shallowest goal state....
  • Null-move heuristic
    Null-move heuristic

    In computer chess programs, the null-move heuristic is a heuristic technique used to enhance the speed of the alpha-beta pruning algorithm....
  • Late Move Reductions
    Late Move Reductions

    Late Move Reduction is a non-game specific enhancement to alpha-beta algorithm and its variants which attempts to examine a game search tree more efficiently....


Leaf evaluation

For most chess positions, computers cannot look ahead to all final possible positions. Instead, they must look ahead a few ply and then evaluate the final board position. The algorithm that evaluates final board positions is termed the "evaluation function
Evaluation function

An evaluation function, also known as a heuristic evaluation function or static evaluation function, is a function used by game-playing programs to estimate the value or goodness of a position in the minimax and related algorithms....
", and these algorithms are often vastly different between different chess programs.

Evaluation functions typically evaluate positions in hundredths of a pawn, and consider material value along with other factors affecting the strength of each side. When counting up the material for each side, typical values for pieces are 1 point for a pawn
Pawn (chess)

The pawn is the weakest and most numerous chess piece in the game of chess, representing infantry, or more particularly armed peasants or pikemen....
, 3 points for a knight
Knight (chess)

The knight is a chess piece in the game of chess, representing a knight . It is normally represented by a horse's head, leading some to refer to it informally as a "horse"....
 or bishop
Bishop (chess)

A bishop is a Chess piece in the board game of chess. Each player begins the game with two bishops. One starts between the king's Knight and the King , the other between the queen's knight and the Queen ....
, 5 points for a rook
Rook (chess)

A rook is a chess piece in the strategy board game of chess. In the past the piece was called the castle, tower, marquess, rector, and comes , and non-players still often call it a "castle"....
, and 9 points for a queen
Queen (chess)

The queen is the most powerful chess piece in the game of chess. Each player starts the game with one queen, placed in the middle of their first rank next to their King ....
. (See Chess piece relative value.) By convention, a positive evaluation favors White, and a negative evaluation favors Black.

The king
King (chess)

In chess, the King is the most important chess piece. The object of the game is to trap the opponent's king so that he would not be able to avoid capture ....
 is sometimes given an arbitrary high value such as 200 points (Shannon's
Claude Elwood Shannon

Claude Elwood Shannon , an United States of America electronic engineer and mathematician, is known as "the father of information theory".Shannon is famous for having founded information theory with one landmark paper published in 1948....
 paper) or 1,000,000,000 points (1961 USSR program) to ensure that a checkmate outweighs all other factors . Evaluation function
Evaluation function

An evaluation function, also known as a heuristic evaluation function or static evaluation function, is a function used by game-playing programs to estimate the value or goodness of a position in the minimax and related algorithms....
s take many factors into account, such as pawn structure, the fact that a pair of bishops are usually worth more, centralized pieces are worth more, and so on. The protection of kings is usually considered, as well as the phase of the game (opening, middle or endgame).

See Claude Elwood Shannon
Claude Elwood Shannon

Claude Elwood Shannon , an United States of America electronic engineer and mathematician, is known as "the father of information theory".Shannon is famous for having founded information theory with one landmark paper published in 1948....
 for a description of his early paper about a chess-playing program.

Using endgame databases


Some computer chess operators have pointed out that endgame tablebase
Endgame tablebase

An endgame tablebase is a computerized database of all chess positions within certain Chess endgames. The tablebase reveals the game theory value of each position , and how many moves it will take to achieve that result with perfect play....
s have the potential to weaken performance strength in chess computers if incorrectly used. Because some positions are analyzed as forced wins for one side, the program will avoid the losing side of positions at all costs. However, many endgames are forced wins only with flawless play, where even a slight error would produce a different result. Consequently, most modern engines will play many endgames well enough on their own. A symptom of this problem is that computers may resign too early because they see that they are being forced into a position that is theoretically dead lost (although they may be thirty or more moves away from the end of the game, and most human opponents would find it hard to win in that time). This observation is only relevant when a computer program is in a situation where it has a choice between two losing moves, one of which is actually more difficult for the opponent, but leads to a tablebase position with a known value, and is hence of very minor importance.

The Nalimov tablebases do not consider the fifty-move rule, under which a game where fifty moves pass without a capture or pawn move can be claimed to be a draw by either player. This results in the tablebase returning results such as "Forced mate in sixty-six moves" in some positions which would actually be drawn because of the fifty-move rule. However, a correctly programmed engine does know about the fifty-move rule, and in any case if using an endgame tablebase will choose the move that leads to the quickest win (even if it would fall foul of the fifty-move rule with perfect play). If playing an opponent not using a tablebase, such a choice will give good chances of winning within fifty moves.

One reason for this is that if the rules of chess were to be changed once more, giving more time to win such positions, it will not be necessary to regenerate all the tablebases. It is also very easy for the program using the tablebases to notice and take account of this 'feature'.

The Nalimov tablebases, which use state-of-the-art compression techniques, require 7.05 GB
Gigabyte

Gigabyte is an SI prefix-multiple of the unit byte for Computer data storage. Since the giga- prefix means 109, gigabyte means 1,000,000,000 bytes ....
 of hard disk space for all five-piece endings. To cover all the six-piece endings requires approximately 1.2 terabyte
Terabyte

A terabyte is a measurement term for computer storage. The value of a terabyte based upon a decimal radix is defined as one 1000000000000 bytes, or 1000 gigabytes....
. It is estimated that seven-piece tablebases will require more storage capacity than will be available in the foreseeable future.

It is surprising, but easily verified, that without an endgame tablebase even otherwise very strong chess engines may fail to find a winning plan even in endings with six or fewer pieces, when they need more moves than the calculation horizon to achieve a checkmate, a win of material or the advance of a pawn. Many endings require more moves than their calculation horizon.

Other optimizations

Many other optimizations can be used to make chess-playing programs stronger. For example, transposition table
Transposition table

In computer chess and other computer games, transposition tables are used to speed up the search of the game tree. Transposition tables are primarily useful in perfect information games, meaning the entire state of the game is known to all players at all times....
s are used to record positions that have been previously evaluated, to save recalculation of them. Refutation tables record key moves that "refute" what appears to be a good move; these are typically tried first in variant positions (since a move that refutes one position is likely to refute another). Opening books aid computer programs by giving common openings that are considered good play (and good ways to counter poor openings).

Of course, faster hardware and additional processors can improve chess-playing program abilities, and some systems (such as Deep Blue) use specialized chess hardware instead of solely software implementations.

Standards

Computer chess programs usually support a number of common de facto standards. Nearly all of today's programs can read and write game moves as Portable Game Notation
Portable Game Notation

Portable Game Notation is a computer-processible format for recording Chess games ; many chess programs recognize this extremely popular format due to its accessibility by ordinary ASCII editors, including word processors capable of importing and exporting plain ASCII....
 (PGN), and can read and write individual positions as Forsyth-Edwards Notation
Forsyth-Edwards Notation

Forsyth-Edwards Notation is a standard Chess notation for describing a particular board position of a Chess game. The purpose of FEN is to provide all the necessary information to restart a game from a particular position....
 (FEN). Older chess programs often only understood long algebraic notation
Algebraic chess notation

Algebraic chess notation is used to record and describe the moves in a game of chess. It is now standard among all chess organizations and most books, magazines, and newspapers....
, but today users expect chess programs to understand standard algebraic chess notation
Algebraic chess notation

Algebraic chess notation is used to record and describe the moves in a game of chess. It is now standard among all chess organizations and most books, magazines, and newspapers....
.

Most computer chess programs are divided into an engine (which computes the best move given a current position) and a user interface. Most engines are separate programs from the user interface, and the two parts communicate to each other using a public communication protocol. The most popular protocol is the Xboard/Winboard Communication protocol. Another open alternate chess communication protocol is the Universal Chess Interface
Universal Chess Interface

The Universal Chess Interface is an open communication protocol that enables a chess program?s engine to communicate with its user interface....
. By dividing chess programs into these two pieces, developers can write only the user interface, or only the engine, without needing to write both parts of the program. (See also List of chess engines
List of chess engines

A chess engine is a computer program that can play the game of chess....
.)

Playing strength versus computer speed

It has been estimated that doubling the computer speed gains approximately fifty to seventy ELO
Elo rating system

The Elo rating system is a method for calculating the relative skill levels of players in two-player games such as chess and Go . It is named after its creator Arpad Elo , a Hungary-born United States physics professor....
 points in playing strength .

Other chess software

There are several other forms of chess-related computer software
Computer software

Computer software, or just software is a general term used to describe a collection of computer programs, Algorithm and Software documentation that perform some tasks on a computer system....
, including the following:
  • Chess game viewers allow players to view a pre-recorded game on a computer. Most chess-playing programs can be also used for this purpose, but some special-purpose software exists.
  • Chess instruction software is designed to teach chess.
  • Chess databases are systems which allow the searching of a large library of historical games. Shane's Chess Information Database
    Shane's Chess Information Database

    Shane's Chess Information Database is a popular Freeware UNIX, Microsoft Windows, Linux, and Mac OS database application for viewing and maintaining databases of chess games....
     (Scid) is a good example of a chess database. Scid may be used under Microsoft Windows
    Microsoft Windows

    Microsoft Windows is a series of software operating systems and graphical user interfaces produced by Microsoft. Microsoft first introduced an operating environment named Windows in November 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces ....
    , UNIX
    Unix

    Unix is a computer operating system originally developed in 1969 by a group of American Telephone & Telegraph employees at Bell Labs, including Ken Thompson , Dennis Ritchie, Douglas McIlroy, and Joe Ossanna....
    , Linux
    Linux

    Linux is a generic term referring to Unix-like computer operating systems based on the Linux kernel. Their development is one of the most prominent examples of free and open source software collaboration; typically all the underlying source code can be used, freely modified, and redistributed by anyone under the terms of the GNU GPL license...
     and Mac OS X
    Mac OS X

    Mac OS X is a line of computer operating systems developed, marketed, and sold by Apple Inc., and since 2002 has been included with all new Macintosh computer systems....
    . There are also commercial databases, such as Chessbase
    ChessBase

    ChessBase is a Germany company that markets chess software, maintains a chess news site, and operates a server for online chess. It maintains and sells massive databases, containing most historic games, that permit analysis that had not been possible prior to computing....
     and Chess Assistant for Windows and ExaChess for Mac OS X.
  • Software for handling chess problems
    Software for handling chess problems

    Software for chess problems is a category of software intended for handling chess problems, usually distinct from Computer chess. Chess problems are based on the rules of chess, but Chess composer may have little use for ordinary chess playing programs....


Advanced chess


Advanced Chess
Advanced Chess

Advanced Chess is a relatively new form of chess, first introduced by International Grandmaster Garry Kasparov, with the objective of a human player and a computer chess playing as a team against other such pairs....
 is a form of chess developed in 1998 by Kasparov where a human plays against another human, and both have access to computers to enhance their strength. The resulting "advanced" player was argued by Kasparov to be stronger than a human or computer alone, although this has not been proven.

Notable theorists

Well-known computer chess theorists include:
  • D. F. Beal
  • David Levy
  • Robert Hyatt
    Robert Hyatt

    Dr. Robert Hyatt is an Associate Professor of Computer science at the University of Alabama at Birmingham. He is the author of the computer chess program Crafty and the co-author of Cray Blitz, a two-time winner of the World Computer Chess Championships....
      (author of open source chess program Crafty
    Crafty

    Crafty is a chess program written by University of Alabama at Birmingham professor Robert Hyatt. It is directly derived from Cray Blitz, winner of the 1983 and 1986 World Computer Chess Championships....
    )
  • Hans Berliner
    Hans Berliner

    Hans Jack Berliner , a Professor of , is a former World Correspondence Chess Champion, from 1965?1968. He is a Grandmaster of Correspondence Chess, and an International Master for List of chess terms#Over-the-board chess....
  • Claude Elwood Shannon
    Claude Elwood Shannon

    Claude Elwood Shannon , an United States of America electronic engineer and mathematician, is known as "the father of information theory".Shannon is famous for having founded information theory with one landmark paper published in 1948....


Future

One potentially fruitful field of research is in distributed computation, where many computers are joined together through the Internet and are each tasked with a small section of the overall search tree to analyse. The leading project is the , which gained a world record in 2004 for the largest number of computers ever playing a game of chess simultaneously (2,070).

Solving chess

The prospects of completely solving
Solved game

A two player game can be "solved" on several levels:Ultra-weakWeakStrongGiven the rules of any two-person game with a finite number of positions, one can always trivially construct a minimax algorithm that would exhaustively traverse the game tree....
 chess are generally considered to be rather remote. It is widely conjectured that there is no computationally inexpensive method to solve chess even in the very weak sense of determining with certainty the value of the initial position, and hence the idea of solving chess in the stronger sense of obtaining a practically usable description of a strategy for perfect play for either side seems unrealistic today. However, it should be noted that neither has it been proven that no computationally cheap way of determining the best move in a chess position exists, nor has it even been proven mathematically that a traditional alpha-beta-searcher running on present-day computing hardware could not solve the initial position in an acceptable amount of time. The difficulty in proving the latter lies in the fact that, while the number of board positions that could happen in the course of a chess game is huge (on the order of 1040), it is hard to rule out with mathematical certainty the possibility that the initial position allows either side to force a mate or a threefold repetition
Threefold repetition

In chess and some other abstract strategy games, the threefold repetition rule states that a player can claim a draw if the same position occurs three times, or will occur after their next move, with the same player to move....
 after relatively few moves, in which case the search tree might encompass only a very small subset of the set of possible positions. It has been mathematically proven that generalized chess (chess played with an arbitrarily large number of pieces on an arbitrarily large chessboard) is EXPTIME-complete, meaning that determining the winning side in an arbitrary position of generalized chess provably takes exponential time in the worst case; however, this theoretical result gives no lower bound on the amount of work required to solve ordinary 8x8 chess. Still, it can certainly be said that nothing indicates a practical possibility of solving chess at present in any sense of the word.

Chronology of computer chess


  • 1769, Wolfgang von Kempelen
    Wolfgang von Kempelen

    Johann Wolfgang Ritter von Kempelen de P?zm?nd was a Hungarian author and inventor with Irish people ancestors....
     builds the Automaton Chess-Player
    The Turk

    The Turk or Automaton Chess Player was a chess-playing artificial intelligence constructed in the late 18th century, and exhibited from 1770 for over 84 years, by various owners, as an automaton but later explained in the early 1820's as an elaborate hoax ....
    , in what becomes one of the greatest hoaxes of its period.
  • 1868, Charles Hooper presented the Ajeeb
    Ajeeb

    Ajeeb was a chess-playing "automaton", created by Charles Hooper , first presented at the Royal Polytechnical Institute in 1868. A particularly intriguing piece of faux mechanical technology , it drew scores of thousands of spectators to its games, the opponents for which included Harry Houdini, Theodore Roosevelt, and O....
     automaton — which also had a human chess player hidden inside.
  • 1912, Leonardo Torres y Quevedo
    Leonardo Torres y Quevedo

    Leonardo Torres y Quevedo , usually Leonardo Torres Quevedo in Spanish language-speaking countries, was a Spanish people engineer and mathematician of the late nineteenth and early twentieth centuries....
     builds a machine that could play King and Rook versus King endgames.
  • 1948, Norbert Wiener
    Norbert Wiener

    Norbert Wiener was an United States theoretical and applied math mathematician.Wiener was a pioneer in the study of stochastic processes and noise processes, contributing work relevant to electronic engineering, electronic communication, and control systems....
    's book Cybernetics describes how a chess program could be developed using a depth-limited minimax search with an evaluation function
    Evaluation function

    An evaluation function, also known as a heuristic evaluation function or static evaluation function, is a function used by game-playing programs to estimate the value or goodness of a position in the minimax and related algorithms....
    .
  • 1950, Claude Shannon publishes "Programming a Computer for Playing Chess", one of the first papers on the problem of computer chess.
  • 1951, Alan Turing
    Alan Turing

    Alan Mathison Turing, Order of the British Empire, Fellow of the Royal Society was a British mathematician, logician and Cryptanalysis....
     develops on paper the first program capable of playing a full game of chess.
  • 1952, Dietrich Prinz develops a program that solves chess problems.
  • 1956, Los Alamos chess
    Los Alamos chess

    Los Alamos chess is a chess variant played on a Minichess without bishop . This was the first chess-like game played by a computer program. This program was written in Los Alamos National Laboratory by Paul Stein and Mark Wells for the MANIAC I computer in 1956....
     is the first program to play a chess-like game, developed by Paul Stein and Mark Wells for the MANIAC I
    MANIAC I

    The MANIAC I was an early computer built under the direction of Nicholas Metropolis at the Los Alamos National Laboratory. It was based on the von Neumann architecture of the IAS machine, developed by John von Neumann....
     computer.
  • 1956, John McCarthy
    John McCarthy (computer scientist)

    John McCarthy , is an United States computer scientist and cognitive scientist who received the Turing Award in 1971 for his major contributions to the field of Artificial Intelligence ....
     invents the alpha-beta search algorithm.
  • 1958, NSS becomes the first chess program to use the alpha-beta search algorithm.
  • 1958, The first programs that could play a full game of chess were developed, one by Alex Bernstein and one by Russia
    Russia

    Russia , or the Russian Federation , is a list of countries spanning more than one continent country extending over much of northern Eurasia....
    n programmers using a BESM
    BESM

    BESM is the name of a series of Soviet Mainframe computer computers built in 1950-1960s. The name is an acronym for "Bolshaya Elektronno-Schetnaya Mashina" , literally "Large Electronic Computing Machine"....
    .
  • 1962, The first program to play credibly, Kotok-McCarthy
    Kotok-McCarthy

    Kotok-McCarthy also known as was the first computer program to play chess convincingly. It is also remembered because it played in and lost the first chess match between two computer programs....
    , is published at MIT
    Massachusetts Institute of Technology

    The Massachusetts Institute of Technology is a private university research university located in Cambridge, Massachusetts, Massachusetts, United States....
  • 1966-1967, The first chess match between computer programs is played. Moscow
    Moscow

    Moscow is the capital and the largest types of inhabited localities in Russia of the Russian Federation. It is also the largest European cities and metropolitan areas, with the Moscow metropolitan area ranking among the largest urban areas in the world....
     Institute for Theoretical and Experimental Physics
    Institute for Theoretical and Experimental Physics

    The Institute for Theoretical and Experimental Physics is located in Moscow, Russia as a Federal Atomic Energy Agency physical institute.Established December 1, 1945, ITEP exists as a community of people studying topics ranging from theoretical physics and mathematics to biology and chemistry....
     (ITEP) defeated Kotok-McCarthy at Stanford University
    Stanford University

    Leland Stanford Junior University, commonly referred to as Stanford University or Stanford, is a private university research university located in Stanford, California, California, United States....
     by telegraph over nine months.
  • 1967, Mac Hack Six
    MacHack (chess)

    'Mac Hack' is a computer chess program written by Richard Greenblatt . Also known as 'Mac Hac' and , it was developed at the Massachusetts Institute of Technology....
    , by Richard Greenblatt
    Richard Greenblatt (programmer)

    Richard D. Greenblatt is an American programmer. He was born in Portland, Oregon. His family moved to Philadelphia, Pennsylvania when he was a child....
     et al. introduces transposition table
    Transposition table

    In computer chess and other computer games, transposition tables are used to speed up the search of the game tree. Transposition tables are primarily useful in perfect information games, meaning the entire state of the game is known to all players at all times....
    s and becomes the first program to defeat a person in tournament play
  • 1970, The first year of the ACM North American Computer Chess Championships
    World Computer Chess Championship

    World Computer Chess Championship is an annual event where computer chess chess engines compete against each other. The event is organized by the International Computer Games Association....
  • 1974, Kaissa
    Kaïssa

    Ka?ssa is a Cameroon born world musician. She moved to Paris with her family at thirteen and to New York City in 1996. Kaissa worked on stage and/or in studio with Salif Keita, Manu Dibango, Kofi Olomide, Papa Wemba, Cesaria Evora, Martha Wash, Diana Ross, Paul Simon, and others....
     wins first World Computer Chess Championship
    World Computer Chess Championship

    World Computer Chess Championship is an annual event where computer chess chess engines compete against each other. The event is organized by the International Computer Games Association....
  • 1977, The first microcomputer chess playing machine, CHESS CHALLENGER, was created
  • 1977, The International Computer Chess Association is established.
  • 1977, Chess 4.6
    Chess (Northwestern University)

    Chess was a pioneering chess engine from the 1970s, authored by Larry Atkin and David Slate at Northwestern University. Chess ran on Control Data Corporation's line of supercomputers....
     becomes the first chess computer to be successful at a major chess tournament.
  • 1980, The first year of the World Microcomputer Chess Championship
  • 1980, The Fredkin Prize is established.
  • 1981 Cray Blitz
    Cray Blitz

    Cray Blitz was a computer chess program written by Robert Hyatt, Harry Nelson, and Albert Gower to run on the Cray supercomputer. It was derived from "Blitz" a program that Hyatt started to work on as an undergraduate....
     won the Mississippi State Championship with a perfect 5-0 score and a performance rating of 2258. In round 4 it defeated Joe Sentef (2262) to become the first computer to beat a master in tournament play and the first computer to gain a master rating.
  • 1982, Ken Thompson's hardware chess player Belle
    Belle (chess machine)

    Belle was the name of a Computer chess and its associated software, developed by J. H. Condon and Ken Thompson at Bell Labs in the 1970s and 1980s....
     earns a US master title.
  • 1988, HiTech
    HiTech

    HiTech was a computer chess built at Carnegie Mellon University under the direction of World Correspondence Chess Champion Dr. Hans J. Berliner, by Berliner, Carl Ebeling, Murray Campbell, and Gordon Goetch....
     developed by Hans Berliner
    Hans Berliner

    Hans Jack Berliner , a Professor of , is a former World Correspondence Chess Champion, from 1965?1968. He is a Grandmaster of Correspondence Chess, and an International Master for List of chess terms#Over-the-board chess....
     and Carl Ebeling
    Carl Ebeling

    Carl Ebeling is an United States computer scientist, professor. His recent interests include coarse-grained reconfigurable architectures of integrated circuits....
     wins a match against grandmaster
    International Grandmaster

    The title Grandmaster is awarded to extremely strong chess masters by the world chess organization FIDE. Apart from "World Chess Championship", Grandmaster is the highest title a chess player can attain....
     Arnold Denker
    Arnold Denker

    Arnold Sheldon Denker was an United States chess player, a Grandmaster , and a chess writer.He was born in New York City, and was a promising boxing in his early years....
     3.5 - 0.5.
  • 1988, Deep Thought
    Deep Thought (chess computer)

    Deep Thought was a computer designed to play chess. Deep Thought was initially developed at Carnegie Mellon University and later at IBM. It was second in the line of chess computers developed by Feng-hsiung Hsu, starting with ChipTest and culminating in IBM Deep Blue....
     shares first place with Tony Miles
    Tony Miles

    Anthony John Miles was an England chess International Grandmaster....
     in the Software Toolworks Championship, ahead of a former world champion Mikhail Tal
    Mikhail Tal

    Mikhail Tal was a Soviet Union-Latvian chess player, a Grandmaster , and the eighth World Chess Champion.He was often called "Misha" and also "The magician from Riga" for his daring combinational style....
     and several grandmasters including Samuel Reshevsky
    Samuel Reshevsky

    Samuel Herman Reshevsky was a famous chess prodigy and later a leading American chess International Grandmaster. He was a contender for the World Chess Championship from about the mid-1930s to the mid-1960s; coming equal third in the World Chess Championship 1948 tournament, and equal second in the 1953 Candidates Tournament....
    , Walter Browne
    Walter Browne

    Walter Shawn Browne is an Australian and United States chess Grandmaster and poker player. Browne has won the U.S. Chess Championship six times....
     and Mikhail Gurevich
    Mikhail Gurevich (chess player)

    Mikhail Naumovich Gurevich is a Ukrainians chess player. He lived in Belgium from 1991 to 2005 and since then resides in Turkey.Gurevich won the Ukrainian Chess Championship in 1984 and became USSR Chess Championship in 1985, controversially taking the title on tiebreak points from co-winners Alexander Chernin and Viktor Gavrikov, after a...
    . It also defeats grandmaster Bent Larsen
    Bent Larsen

    J?rgen Bent Larsen is a Denmark chess Grandmaster . He has been a six-time Danish Chess Championship, and a Candidate for the World Chess Championship on four occasions: 1965, 1968, 1971, and 1977....
    , making it the first computer to beat a GM in a tournament. Its rating
    Elo rating system

    The Elo rating system is a method for calculating the relative skill levels of players in two-player games such as chess and Go . It is named after its creator Arpad Elo , a Hungary-born United States physics professor....
     for performance in this tournament of 2745 (USCF scale) was the highest obtained by a computer player.
  • 1989, Deep Thought loses two exhibition games to Garry Kasparov
    Garry Kasparov

    Garry Kasparov is a Russian former World Chess Champion, regarded by many as Methods for comparing top chess players throughout history. He is also a writer and political activist....
    , the reigning world champion.
  • 1992, first time a microcomputer
    Microcomputer

    A microcomputer is a computer with a microprocessor as its central processing unit. Another general characteristic of these computers is that they occupy physically small amounts of space when compared to mainframe computer and minicomputers....
    , the ChessMachine
    Chessmachine

    The ChessMachine was a chess engine sold between 1991 and 1995 by TASC . It was unique at the time for incorporating both an ARM architecture coprocessor for the chess engine on an ISA bus which plugged into a IBM PC and a software interface running on the PC to display a chess board and control the engine....
     Gideon 3.1
    REBEL (chess)

    REBEL was a world champion chess program developed by Ed Schr?der. Development of REBEL started in 1980 on a TRS-80, and it was ported many times to dedicated hardware and the fastest microprocessors of the day:...
     by Ed Schröder from The Netherlands, wins the 7th World Computer Chess Championship
    World Computer Chess Championship

    World Computer Chess Championship is an annual event where computer chess chess engines compete against each other. The event is organized by the International Computer Games Association....
     in front of mainframes
    Mainframe computer

    Mainframes are computers used mainly by large organizations for critical applications, typically bulk data processing such as census, industry and consumer statistics, Enterprise Resource Planning, and financial transaction processing....
    , supercomputer
    Supercomputer

    A supercomputer is a computer that is at the frontline of current processing capacity, particularly speed of calculation. Supercomputers introduced in the 1960s were designed primarily by Seymour Cray at Control Data Corporation , and led the market into the 1970s until Cray left to form his own company, Cray Research....
    s and special hardware.
  • 1997, Deep Blue wins a six-game match against Garry Kasparov
    Garry Kasparov

    Garry Kasparov is a Russian former World Chess Champion, regarded by many as Methods for comparing top chess players throughout history. He is also a writer and political activist....
    .
  • 2002, Vladimir Kramnik
    Vladimir Kramnik

    Vladimir Borisovich Kramnik is a Russian chess International Grandmaster. He was Classical World Chess Championship 2000 from 2000 to 2006, and undisputed World Chess Champion from 2006 to 2007....
     draws an eight-game match against Deep Fritz.
  • 2003, Kasparov draws a six-game match against Deep Junior
    Deep Junior

    Junior is a computer chess program authored by the Israeli programmers Amir Ban and Shay Bushinsky. Grandmaster Boris Alterman assisted, in particular with the opening book....
    .
  • 2003, Kasparov draws a four-game match against X3D Fritz
    X3D Fritz

    X3D Fritz was a version of the Fritz , which in November 2003 played a four game Human-computer chess match against world number one International Grandmaster Garry Kasparov....
    .
  • 2005, Hydra
    Hydra (chess)

    Hydra is a chess machine, designed by a team with Christian Donninger, Dr. Ulf Lorenz, International Grandmaster Christopher Lutz and Muhammad Nasir Ali....
     defeats Michael Adams
    Michael Adams

    Michael Adams is a United Kingdom Grandmaster of chess. His highest ranking is world number 4, achieved several times from October 2000 to October 2002....
     5.5-0.5.
  • 2005, a team of computers (Hydra
    Hydra (chess)

    Hydra is a chess machine, designed by a team with Christian Donninger, Dr. Ulf Lorenz, International Grandmaster Christopher Lutz and Muhammad Nasir Ali....
    , Deep Junior
    Deep Junior

    Junior is a computer chess program authored by the Israeli programmers Amir Ban and Shay Bushinsky. Grandmaster Boris Alterman assisted, in particular with the opening book....
     and Fritz
    Fritz (chess)

    Fritz is a Germany computer chess developed by Frans Morsch and Mathias Feist and published by ChessBase. There is also a version called Deep Fritz that is designed for multi-processing....
    ), wins 8.5-3.5 against a rather strong human team formed by Veselin Topalov
    Veselin Topalov

    Veselin Topalov is a Bulgarian chess International Grandmaster and former FIDE world chess champion.Topalov became the FIDE World Chess Champion by winning the FIDE World Chess Championship 2005....
    , Ruslan Ponomariov
    Ruslan Ponomariov

    Ruslan Ponomariov is a Ukraine chess player and former FIDE world champion.On the January 2009 F?d?ration Internationale des ?checs Elo rating list Ponomariov had a rating of 2726, making him number sixteen in the world and the Ukrainian number two, behind Vassily Ivanchuk....
     and Sergey Karjakin
    Sergey Karjakin

    Sergey Karjakin is a Ukraine chess Grandmaster . He was a chess prodigy and holds the record for the youngest grandmaster in history, achieving the title at the age of twelve years and seven months....
    , who had an average ELO
    Elo rating system

    The Elo rating system is a method for calculating the relative skill levels of players in two-player games such as chess and Go . It is named after its creator Arpad Elo , a Hungary-born United States physics professor....
     rating of 2681.
  • 2006, the undisputed world champion, Vladimir Kramnik
    Vladimir Kramnik

    Vladimir Borisovich Kramnik is a Russian chess International Grandmaster. He was Classical World Chess Championship 2000 from 2000 to 2006, and undisputed World Chess Champion from 2006 to 2007....
    , is defeated 4-2 by Deep Fritz.


See also

  • Advanced Chess
    Advanced Chess

    Advanced Chess is a relatively new form of chess, first introduced by International Grandmaster Garry Kasparov, with the objective of a human player and a computer chess playing as a team against other such pairs....
  • Chess Engines Grand Tournament
  • Chess engine
  • Computer Go
    Computer Go

    Computer go is the field of artificial intelligence dedicated to creating a computer program that plays Go , an ancient board game....
  • Computer shogi
    Computer shogi

    Computer shogi is a field of artificial intelligence concerned with the creation of computer programs which can play shogi. The research and development of shogi software has been carried out mainly by freelance programmers, university research groups and private companies....
  • Computer Olympiad
    Computer Olympiad

    The Computer Olympiads are a multi-games event taking place every year in which computer programs compete against each other. The majority of the games are board games but other games such as Contract bridge take place as well....
  • Internet chess server
    Internet chess server

    An Internet chess server is an external Server that provides the facility to play, discuss, and view chess over the Internet. The term specifically refers to facilities for connecting players through a variety of graphical chess clients located on each user's computer....
  • List of chess video games
    List of chess video games

    This is a list of chess video games:*Battle Chess*Crafty Chess*''Chessmaster*''ChessNet*''Chess Crusade*''Clubhouse Games*''DSChess...
  • Swedish Chess Computer Association
    Swedish Chess Computer Association

    The Swedish Chess Computer Association is an organization that tests computer chess software by playing chess programs against one another and producing a rating list....
  • World Computer Chess Championship
    World Computer Chess Championship

    World Computer Chess Championship is an annual event where computer chess chess engines compete against each other. The event is organized by the International Computer Games Association....


Further reading

  • Newborn, Monty (1996). Outsearching Kasparov, American Mathematical Society's Proceeding of Symposia in Applied Mathematics: Mathematical Aspects of Artificial Intelligence, v. 55, pp 175–205, 1998. Based on paper presented at the 1996 Winter Meeting of the AMS, Orlando, Florida, Jan 9–11, 1996.
  • Newborn, Monty (2000). Deep Blue’s contribution to AI, Annals of Mathematics and Artificial Intelligence, v. 28, pp. 27-30, 2000.
  • Newborn, Monty (2006). , Seattle, Washington, August 18, 2006

External links

  • , an article by Tim Krabbé about "anti-computer style" chess
  • - Bulletin board where professional authors discuss their programs
  • - Play chess against Ken Thompson's endgame database
  • - Online computer chess museum and blog
  • Media
    • The History of Computer Chess: An AI Perspective. Watch Full Lecture - | featuring Murray Campbell (IBM Deep Blue Project), Edward Feigenbaum, David Levy, John McCarthy, and Monty Newborn. at
    • (2 hour video - series of lectures)
    • (2 hour video)