Reversi
Encyclopedia
Reversi is a board game involving abstract strategy
Abstract strategy game
An abstract strategy game is a strategy game, aiming to minimise luck, and without a theme. Almost all abstract strategy games will conform to the strictest definition of: a board or card game, in which there is no hidden information, no non-deterministic elements , in which two players or teams...

 and played by two players on a board with 8 rows and 8 columns and a set of distinct pieces for each side. Pieces typically are disks with a light and a dark face, each face belonging to one player. The player's goal is to have a majority of their colored pieces showing at the end of the game, turning over as many of their opponent's pieces as possible.

Origins

The modern version is based on the game reversi that was invented in 1883 by either of two Englishmen (each calling the other a fraud), Lewis Waterman or John W. Mollett (or perhaps earlier by someone else entirely), and gained considerable popularity in England at the end of the 19th century. The game's first known-to-be reliable mention is in 21 August 1886 edition of The Saturday Review
Saturday Review (London)
The Saturday Review of politics, literature, science, and art was a London weekly newspaper established by A. J. B. Beresford Hope in 1855....

. Later mention includes an 1895 article in the New York Times: "Reversi is something like Go Bang
Go-Bang
Go-Bang is an English musical comedy with words by Adrian Ross and music by F. Osmond Carr.The piece was produced by Fred Harris and opened at the Trafalgar Square Theatre on 10 March 1894. It ran for 159 performances. The show starred Harry Grattan, George Grossmith, Jr., Arthur Playfair,...

, and is played with 64 pieces." In 1893, the well-known German games publisher Ravensburger
Ravensburger
Ravensburger Spieleverlag GmbH is a German game company. It is a leader in the European puzzle market.-History:The company was founded by Otto Robert Maier with seat in Ravensburg, a town in Upper Swabia in southern Germany. He began publishing in 1883 with his first author contract...

 started producing the game as one of its first titles. Two 18th century continental European books dealing with a game that may or may not be the one with which we are concerned are mentioned on page 14 of the Spring 1989 Othello Quarterly
Othello Quarterly
The Othello Quarterly was the journal of the United States Othello Association, and was dedicated to the modern version of the game whose generic name is Reversi. It was published from the late 1970s until circa 2007....

, and there has been speculation, so far without documentation, that the game has more ancient origins.

The modern rule set used on the international tournament stage originated in Mito, Ibaraki
Mito, Ibaraki
is the capital of Ibaraki Prefecture, Japan and has a central location, moderately offset towards the coast in that prefecture. As of 2005, the city has an estimated population of 263,748 and a total area is 217.45 km², giving a population density of 1,212.91 persons per km²...

, Japan in the 1970s: the Japanese game company Tsukuda Original registered the game under the trademark name Othello. The name was selected as a reference to the Shakespeare
William Shakespeare
William Shakespeare was an English poet and playwright, widely regarded as the greatest writer in the English language and the world's pre-eminent dramatist. He is often called England's national poet and the "Bard of Avon"...

an play Othello, the Moor of Venice
Othello
The Tragedy of Othello, the Moor of Venice is a tragedy by William Shakespeare, believed to have been written in approximately 1603, and based on the Italian short story "Un Capitano Moro" by Cinthio, a disciple of Boccaccio, first published in 1565...

, referencing the conflict between the Moor
Moors
The description Moors has referred to several historic and modern populations of the Maghreb region who are predominately of Berber and Arab descent. They came to conquer and rule the Iberian Peninsula for nearly 800 years. At that time they were Muslim, although earlier the people had followed...

 Othello and Iago, who describes himself as "two faced" and more controversially, to the unfolding drama between Othello, who is black, and Desdemona
Desdemona (Othello)
Desdemona is a character in William Shakespeare's play Othello . Shakespeare's Desdemona is a Venetian beauty who enrages and disappoints her father, a Venetian senator, when she elopes with Othello, a man several years her senior. When her husband is deployed to Cyprus in the service of the...

, who is white. The green colour of the board is inspired by the image of the general Othello, valiantly leading his battle in a green field. It can also be likened to a jealousy competition (jealousy being the central theme in Shakespeare's play), since players engulf the pieces of the opponent, thereby turning them to their possession.

A 2002 press release about the origins of the modern game makes no mention of the original version:
"Othello was invented by Japanese game enthusiast, Goro Hasegawa in 1971. He chose James R. Becker, to help him develop and market the game. Inspired by the ancient Chinese strategy game 'Go
Go (board game)
Go , is an ancient board game for two players that originated in China more than 2,000 years ago...

', Hasegawa sought to create a game that was rich in strategy, but still approachable by the casual player. Becker simplified the game play, coined the tagline, 'A Minute to Learn...A Lifetime to Master' and named this new game after Shakespeare's classic play, because of the black and white disks. Othello was first introduced in Japan in 1973, by Tsukuda Original Co., who at Becker's suggestion organized the Japanese Othello Association."


In 1973, Othello became a commercial success in Japan and held its first national championship.
Goro Hasegawa, who wrote How to win at Othello, popularized the game in Japan in 1975.

Rules

Each of the two sides corresponds to one player; they are referred to here as light and dark after the sides of Othello pieces, but "heads" and "tails" would identify them equally well, so long as each marker has sufficiently distinctive sides.

Reversi did not have a defined starting position. Othello's rules, however, state that the game begins with four markers placed in a square in the middle of the grid, two facing light-up, two pieces with the dark side up. The dark player makes the first move.

Dark must place a piece with the dark side up on the board, in such a position that there exists at least one straight (horizontal, vertical, or diagonal) occupied line between the new piece and another dark piece, with one or more contiguous light pieces between them. In the below situation, dark has the following options indicated by transparent pieces:

After placing the piece, dark turns over (flips, captures) all light pieces lying on a straight line between the new piece and any anchoring dark pieces. All reversed pieces now show the dark side, and dark can use them in later moves—unless light has reversed them back in the meantime. In other words, a valid move is one where at least one piece is reversed.

If dark decided to put a piece in the topmost location (all choices are strategically equivalent at this time), one piece gets turned over, so that the board appears thus:

Now light plays. This player operates under the same rules, with the roles reversed: light lays down a light piece, causing a dark piece to flip. Possibilities at this time appear thus (indicated by transparent pieces):

Light takes the bottom left option and reverses one piece:

Players take alternate turns. If one player cannot make a valid move, play passes back to the other player. When neither player can move, the game ends. This occurs when the grid has filled up or when neither player can legally place a piece in any of the remaining squares. This means the game ends before the grid is completely filled. This possibility may occur because one player has no pieces remaining on the board in his or her color. In over-the-board play this is generally scored as if the board was full (64-0).

Example where the game ends before the grid is completely filled:

The player with the most pieces on the board at the end of the game wins. An exception to this is that if a clock is employed then if one player defaults on time that player's opponent wins regardless the board configuration, with varying methods to determine the official score where one is required.

In common practice over the internet, opponents agree upon a time-control of, typically, from 1 to 30 minutes per game per player. Standard time control in the World Championship is 30 minutes, and this or something close to it is common in over-the-board (as opposed to internet) tournament play generally. In time-defaulted games, where disk differential is used for tiebreaks in tournaments or for rating purposes, one common over-the-board procedure for the winner of defaulted contests to complete both sides' moves with the greater of the result thereby or one disk difference in his or her favor being the recorded score.

Significant variants of the game, such as where the starting position differs from standard or the objective is to have the fewest pieces one's color at the end, are sometimes—but rarely—played.

Strategic elements

Strategic concepts in Reversi include corners, mobility, edge play, parity, endgame play and looking ahead.

Corners

Corner positions, once played, remain immune to flipping for the rest of the game (because there is no other opposite color behind them to create a flip); thus a player could use a piece in a corner of the board to anchor groups of pieces (starting with the adjacent edges) permanently. Therefore, capturing a corner often proves an effective strategy when the opportunity arises. More generally, a piece is stable when, along all four axes (horizontal, vertical, and each diagonal), it is on a boundary, in a filled row, or next to a stable piece of the same color. Grabbing a corner prematurely may be a mistake, however, if in doing so the player leaves "holes" along the edge. These holes can be filled by the opposing player and could result in capture of some or most of the pieces along that edge. This renders occupying the corner largely useless.

Mobility

An opponent playing with reasonable strategy will not so easily relinquish the corner or any other good moves. So to achieve these good moves, a player must force his or her opponent to play moves that relinquish those good moves. One of the ways to achieve this involves reducing the number of moves available to the player's opponent.
Ideally, this will eventually force the opponent to make an undesirable move.

Edges

Edge pieces can anchor flips that influence moves to all regions of the board. If played poorly, this can poison later moves by causing players to flip too many pieces and open up many moves for the opponent. However, playing on edges where an opponent cannot easily respond drastically reduces possible moves for that opponent.

The square immediately diagonally adjacent to the corner (called the X-square), when played in the early or middle game, typically guarantees the loss of that corner. Nevertheless, such a corner sacrifice is sometimes played for some strategic purpose (like retaining mobility). Playing to the edge squares adjacent to the corner (called the C-squares) can also be dangerous if it gives the opponent powerful forcing moves.

Parity

Parity is one of the most important parts of the strategy. In short, the concept of parity is about getting the last move in every empty region in the end-game, and thereby increasing the number of stable discs.

The concept of parity led to a change in the perception of the game, as it led to distinct strategies for playing black and white. It forced black to play more aggressive moves and gave white the opportunity to stay calm and focus on keeping the parity. As a result the opening books and mid-game were focused on black being the "attacker" and white being the "defender".

The concept of parity also controls how edge positions are played and how edges interact.

Endgame

For the endgame (the last 20 or so moves of the game) the strategies will typically change. Special techniques such as sweeping, gaining access, and the details of move-order can have a large impact on the outcome of the game. Actual counting of discs in the very final stages is often critical, and in human play an inaccurate choice for disk differential can be better than an accurate one in terms of the expected outcome.

Brightwell Quotient

Invented by the British Mathematician and 3 times vice World Champion and 5 times British Champion Graham Brightwell
Graham Brightwell
Graham Brightwell is a British mathematician working in the field of discrete mathematics.His Erdős number is 2 owing to his numerous publications with Béla Bollobás....

, this is as tiebreaker, that is now used in many tournaments including the WOC. If two players have the same number of points in the 13 rounds WOC swiss, the tie is resolved in favour of the player with the higher Brightwell Quotient.

Computer opponents and research

Because of difficulties in human lookahead—peculiar to Reversi because of the apparent strategic meaninglessness of internal disks (this makes blindfold games almost impossible) and the attractiveness of the game to programmers, the best Othello computer
Computer Othello
is a reversi-based video arcade game developed and published by Nintendo. It is one of their earliest video arcade games along with Block Fever and after they did release a dedicated console called Color TV Game 6 and a variety of electromechanical arcade games earlier in the 1970s. It was...

 programs have easily defeated the best humans since 1980, when the program The Moor beat the reigning world champion. In 1997, Logistello
Logistello
Logistello is a computer program that plays the game Othello, also known as Reversi. Logistello was written by Michael Buro and is regarded as a strong player, having beaten the human world champion Takeshi Murakami six games to none in 1997 — the best Othello programs are now much stronger...

 defeated the human champion Takeshi Murakami with a score of 6:0.

Analysts have estimated the number of legal positions in Othello is at most 1028, and it has a game-tree complexity of approximately 1058. Mathematically, Othello still remains unsolved. Experts have not absolutely resolved what the outcome of a game will be where both sides use perfect play. However, analysis of thousands of high-quality games (most of them computer-generated) has led to the strong conclusion (pending actual proof) that, on the standard 8-by-8 board, perfect play on both sides results in a draw. When generalizing
Generalized game
In computational complexity theory, a generalized game is a game that has been generalized so that it can be played on a board of any size. For example, generalized chess is the game of chess played on an n-by-n board, with 2n pieces on each side.Complexity theory studies the asymptotic difficulty...

 the game to play on an n-by-n board, the problem of determining if the first player has a winning move in a given position is PSPACE-complete
PSPACE-complete
In complexity theory, a decision problem is PSPACE-complete if it is in the complexity class PSPACE, and every problem in PSPACE can be reduced to it in polynomial time...

. On 4-by-4 and 6-by-6 boards under perfect play, the second player wins. The first of these results is relatively trivial, and the second dates to around 1990.

World Othello Championship

Year Location World Champion Country Team Runner-Up Country
1977 Tokyo Hiroshi Inoue N/A Thomas Heiberg
1977* Monte Carlo
Monte Carlo
Monte Carlo is an administrative area of the Principality of Monaco....

 
Sylvain Perez   France N/A Michel Rengot (Blanchard)   France
1978 New York Hidenori Maruoka N/A Carol Jacobs
Carol Jacobs
Carol Jacobs is a former American othello player. In 1978, she was runner-up in the World Othello Championship and was the United States champion 1977 and 1978. She placed 4th at the 1977 World Othello Championship and was runner-up at the 1978 WOC. She was born in New York City.-References:*...

 
  USA
1979 Rome Hiroshi Inoue N/A Jonathan Cerf    USA
1980 London Jonathan Cerf   USA N/A Takuya Mimura
1981 Brussels
Brussels
Brussels , officially the Brussels Region or Brussels-Capital Region , is the capital of Belgium and the de facto capital of the European Union...

 
Hidenori Maruoka N/A Brian Rose   USA
1982 Stockholm
Stockholm
Stockholm is the capital and the largest city of Sweden and constitutes the most populated urban area in Scandinavia. Stockholm is the most populous city in Sweden, with a population of 851,155 in the municipality , 1.37 million in the urban area , and around 2.1 million in the metropolitan area...

 
Kunihiko Tanida N/A David Shaman   USA
1983 Paris Ken'Ichi Ishii N/A Imre Leader
Imre Leader
Imre Bennett Leader is a British mathematician and Professor of Pure Mathematics, specifically combinatorics, at the University of Cambridge....

 
1984 Melbourne Paul Ralle   France N/A Ryoichi Taniguchi
1985 Athens
Athens
Athens , is the capital and largest city of Greece. Athens dominates the Attica region and is one of the world's oldest cities, as its recorded history spans around 3,400 years. Classical Athens was a powerful city-state...

 
Masaki Takizawa N/A Paolo Ghirardato
1986 Tokyo Hideshi Tamenori N/A Paul Ralle   France
1987 Milan
Milan
Milan is the second-largest city in Italy and the capital city of the region of Lombardy and of the province of Milan. The city proper has a population of about 1.3 million, while its urban area, roughly coinciding with its administrative province and the bordering Province of Monza and Brianza ,...

 
Ken'Ichi Ishii   USA Paul Ralle   France
1988 Paris Hideshi Tamenori Graham Brightwell
Graham Brightwell
Graham Brightwell is a British mathematician working in the field of discrete mathematics.His Erdős number is 2 owing to his numerous publications with Béla Bollobás....

 
1989 Warsaw
Warsaw
Warsaw is the capital and largest city of Poland. It is located on the Vistula River, roughly from the Baltic Sea and from the Carpathian Mountains. Its population in 2010 was estimated at 1,716,855 residents with a greater metropolitan area of 2,631,902 residents, making Warsaw the 10th most...

 
Hideshi Tamenori Graham Brightwell
Graham Brightwell
Graham Brightwell is a British mathematician working in the field of discrete mathematics.His Erdős number is 2 owing to his numerous publications with Béla Bollobás....

 
1990 Stockholm
Stockholm
Stockholm is the capital and the largest city of Sweden and constitutes the most populated urban area in Scandinavia. Stockholm is the most populous city in Sweden, with a population of 851,155 in the municipality , 1.37 million in the urban area , and around 2.1 million in the metropolitan area...

 
Hideshi Tamenori   France Didier Piau   France
1991 New York Shigeru Kaneda   USA Paul Ralle   France
1992 Barcelona
Barcelona
Barcelona is the second largest city in Spain after Madrid, and the capital of Catalonia, with a population of 1,621,537 within its administrative limits on a land area of...

 
Marc Tastet   France David Shaman
1993 London David Shaman   USA   USA Emmanuel Caspard   France
1994 Paris Masaki Takizawa   France Karsten Feldborg
1995 Melbourne Hideshi Tamenori   USA David Shaman   USA
1996 Tokyo Takeshi Murakami Stéphane Nicolet   France
1997 Athens
Athens
Athens , is the capital and largest city of Greece. Athens dominates the Attica region and is one of the world's oldest cities, as its recorded history spans around 3,400 years. Classical Athens was a powerful city-state...

 
Makoto Suekuni Graham Brightwell
Graham Brightwell
Graham Brightwell is a British mathematician working in the field of discrete mathematics.His Erdős number is 2 owing to his numerous publications with Béla Bollobás....

 
1998 Barcelona
Barcelona
Barcelona is the second largest city in Spain after Madrid, and the capital of Catalonia, with a population of 1,621,537 within its administrative limits on a land area of...

 
Takeshi Murakami   France Emmanuel Caspard   France
1999 Milan
Milan
Milan is the second-largest city in Italy and the capital city of the region of Lombardy and of the province of Milan. The city proper has a population of about 1.3 million, while its urban area, roughly coinciding with its administrative province and the bordering Province of Monza and Brianza ,...

 
David Shaman Tetsuya Nakajima
2000 Copenhagen
Copenhagen
Copenhagen is the capital and largest city of Denmark, with an urban population of 1,199,224 and a metropolitan population of 1,930,260 . With the completion of the transnational Øresund Bridge in 2000, Copenhagen has become the centre of the increasingly integrating Øresund Region...

 
Takeshi Murakami   USA Brian Rose   USA
2001 New York Brian Rose   USA   USA Raphael Schreiber   USA
2002 Amsterdam
Amsterdam
Amsterdam is the largest city and the capital of the Netherlands. The current position of Amsterdam as capital city of the Kingdom of the Netherlands is governed by the constitution of August 24, 1815 and its successors. Amsterdam has a population of 783,364 within city limits, an urban population...

 
David Shaman   USA Ben Seeley   USA
2003 Stockholm
Stockholm
Stockholm is the capital and the largest city of Sweden and constitutes the most populated urban area in Scandinavia. Stockholm is the most populous city in Sweden, with a population of 851,155 in the municipality , 1.37 million in the urban area , and around 2.1 million in the metropolitan area...

 
Ben Seeley   USA Makoto Suekuni
2004 London Ben Seeley   USA   USA Makoto Suekuni
2005 Reykjavík
Reykjavík
Reykjavík is the capital and largest city in Iceland.Its latitude at 64°08' N makes it the world's northernmost capital of a sovereign state. It is located in southwestern Iceland, on the southern shore of Faxaflói Bay...

 
Hideshi Tamenori Kwangwook Lee
2006 Mito
Mito, Ibaraki
is the capital of Ibaraki Prefecture, Japan and has a central location, moderately offset towards the coast in that prefecture. As of 2005, the city has an estimated population of 263,748 and a total area is 217.45 km², giving a population density of 1,212.91 persons per km²...

 
Hideshi Tamenori Makoto Suekuni
2007 Athens
Athens
Athens , is the capital and largest city of Greece. Athens dominates the Attica region and is one of the world's oldest cities, as its recorded history spans around 3,400 years. Classical Athens was a powerful city-state...

 
Kenta Tominaga Stéphane Nicolet   France
2008 Oslo
Oslo
Oslo is a municipality, as well as the capital and most populous city in Norway. As a municipality , it was established on 1 January 1838. Founded around 1048 by King Harald III of Norway, the city was largely destroyed by fire in 1624. The city was moved under the reign of Denmark–Norway's King...

 
Michele Borassi Tamaki Miyaoka
2009 Ghent
Ghent
Ghent is a city and a municipality located in the Flemish region of Belgium. It is the capital and biggest city of the East Flanders province. The city started as a settlement at the confluence of the Rivers Scheldt and Lys and in the Middle Ages became one of the largest and richest cities of...

 
Yusuke Takanashi Matthias Berg   Germany
2010 Rome
Rome
Rome is the capital of Italy and the country's largest and most populated city and comune, with over 2.7 million residents in . The city is located in the central-western portion of the Italian Peninsula, on the Tiber River within the Lazio region of Italy.Rome's history spans two and a half...

 
Yusuke Takanashi  Michele Borassi
2011 Newark NJ
Newark, New Jersey
Newark is the largest city in the American state of New Jersey, and the seat of Essex County. As of the 2010 United States Census, Newark had a population of 277,140, maintaining its status as the largest municipality in New Jersey. It is the 68th largest city in the U.S...



*This rivalling Monte Carlo world championship is usually not considered to be an official world championship. In official homepages it is called the first European Championship.

Further reading

Othello books to increase skill to tournament-level play:

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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