Reversi

Othello and Reversi are two closely related strategic board games for two people.

History

In the 1880s, the Englishman Lewis Waterman developed a board game, which he called Reversi (Latin reversible). It was played on a chessboard with 64 stones. His game was similar to Game of Annexation ( Game of the annexation ), which was invented in 1870 by Englishman John W. Mollett. Mollet's game but was played on a cross-shaped board. Both lived in London and claimed the true inventor to be. There was a lawsuit and eventually they will have even fought a duel. The oldest known source to Watermans Reversi is a newspaper article of 21 August 1886 in the " The Saturday Review ". After 1888 Walter H. Peel under the pseudonym " Berkeley " published some articles about Reversi in the magazine "The Queen", the game was known. It was quickly followed by other publications, including Peel also the "Handbook of Reversi ", which was published in 1888 by Watermans company Jacques and Sons, and the experienced several new editions in the following decades.

The company Ravensburger sold since 1893 Reversi game boards and brought several family-friendly issues like " cops and robbers " or " turning the thing " on the market. Reversi is a registered trademark of Ravensburger is therefore part of the most successful games of the modern era. Even in the English language Reversi has remained unknown. Thus, for example, the English historian Games RC Bell dealt with Reversi and the American science writer Martin Gardner suggested in April 1960 in the journal Scientific American a discussion on the shortest possible game of Reversi.

1971 reported the Japanese Gorō Hasegawa (长谷川 五郎) the variant Othello in Japan as a trademark, without, as he claimed to have had knowledge of Reversi. His father was an English teacher and suggested, because of the analogy to Shakespeare's Othello, this name before.

The main differences are that in Othello, the first four stones are set as the opening, and Reversi each player has exactly 32 stones only. In Germany Reversi is often played as such, that only one row is reversed. Originally, however, each series was included in Reversi, as in Othello, conquered.

Today, Othello, Shogi addition, Go and Renju, one of the most popular board games in Japan, where it is played by about 25 million people. In Europe and North America the great success failed. Instead, here Reversi is often sold with the note to be able to play it with modified rules.

Othello is the game with the most annual World Championships ( since 1977) under licensing arrangements. In tournaments in Germany and in the Netherlands usually Othello boards are used, how they are marketed by Universal Trends in Germany. For World Championships the even larger boards of the Japanese publisher Megahouse be used (formerly Tsukuda ).

With the development of computer and the quality of play increased, and thanks to its simple rules in place Othello gain increasing popularity as a computer and online game ( mostly due to licensing issues under the name Reversi or neologisms such as " Drehum " or " Revello "). Since the turn of the century increases with proliferation of the Internet and clearly the number of recreational and tournament players.

Regulate

In an 8 × 8 board, players take turns playing pieces, their pages differently ( black and white) are colored. One player ( " White " ) always puts his stone with the white side up, the other ( "black" ) in accordance with the black. When the game starts, there are four stones in a predetermined arrangement on the board. A player must place his stone on an empty space adjacent horizontally, vertically or diagonally to an assigned name. If a checker is specified, all opponent's stones that are located between the new tile and one already laid stone of their color, reversed. Moves that do not lead to an instant of opponent stones are not allowed. The objective of the game is to have as large a number of stones of their own color on the board at the end.

The exact rules:

• It is played on a board with 8 x 8 squares.
• Applies only to the variant Othello: two white and two black stones are as grid before the start of the game placed on the central cells of the board, the two diagonally opposite with the same color (picture).
• Applies only to the variant Reversi (Jacques and Sons ): In the first two moves, both players put each one of their stones ( red or black ) to the four center panels. It can therefore creates two " starting grids ", where the second player gets to choose this de facto.
• Applies only to the variant Reversi ( Ravensburger ): In the first train both players put two of their stones ( colors depending edition, for example, red and green, white and red, red and yellow ) on the four center panels. It can therefore creates two " starting grids ", where the first player gets to choose this de facto.
• In the variant Reversi at the beginning of each player has a supply of 32 stones in Othello, the number of stones is unlimited.
• Players take turns, Black begins (Jacques and Sons: red). It requires either a stone with its own color to the top of an empty field, or one fits. Passing is only allowed if you have no legal way to put a stone.
• One can only put so that, starting from the set stone in any direction ( vertically, horizontally or diagonally ) followed by one or more opposing pieces and then is a separate stone. At least one opposing checker are included on the set stone and another of his stones in a straight line so. In this case, all fields between the two own pieces of enemy stones must be occupied.
• All opponent's stones that are so included, change the color, they are reversed. This is done as part of the same move before the opponent comes to train. A train can include multiple rows simultaneously opposing pieces, which are then all reversed. If, however, includes a straight inverted stone more opposing pieces, they are not reversed.
• If the players successively fit directly, so if no one can put a stone more, the game is over. When Reversi is the case when both players either do not have or more stones can turn no more opposing checkers.
• The player who at the end with the most pieces of his color on the board wins. If both have the same number, the game is a draw.
• To determine the amount of profit, there are different rules. Most are the fields that are empty even when the game ends, credited to the winner, that is added to the difference of the number of stones.
• With an additional rule that is often used in Japanese tournaments, you can avoid a draw: a player (which will be drawn, for example ) determines whether an equal number of stones is evaluated at game end as a victory for white or black. The other player then chooses a color.

Pragmatic rules for games without computer assistance:

• Once a specified piece may no longer be removed from the board.
• If a player has a stone wrongly reversed or forgotten to turn one, this can be corrected by both parties until the opponent has made his next train. Then remain false or not be overturned stones.

Strategy

Stability

Positioned to have a cornerstone, brings with it the advantage that this stone can not be captured by the enemy, since it can not be surrounded by enemy stones and thus reversed. Such a token that can no longer change color is stable stone ( ' stable disc ') called, because his position later in the game is stable. Based on a stable stone can often annexing adjacent stones, which can also be stable stones.

Figure stable discs you can see the starting position before the last two moves. White still has 20 blocks, half of which is stable and can not be reversed. However, the stones of the A and the B column and the eight series are not yet stable. Now only Black can draw and only on A8. Instant White loses the stones B7, B8, C8 and D8. These stones are now stable for black. With the last train Black takes all the stones of the A- column. White thus loses all non- stable stones.

X - and C- fields

Some fields have special names, as they are particularly important in the game. These are the fields in addition to the corners: The field at the diagonal corner of the front is called the X field (B2, B7, G2, G7), the other two fields are adjacent to the corner, C fields (A2, B1, A7, B8, G1, H2, H7, G8).

Within the field of play different regions can be distinguished according to the principle of the compass. Thus, the region is known around the corner H1 as the North -East region.

Mobility, tempo, walls and quiet trains

In the last section, the value of the property corners and generally stable stones and the danger was declared when setting on x and c fields. So there is already in the middle game good and bad traits. One can thus formulate the strategic goal to force the opponent to bad on trains and to avoid being forced to do that to poor trains. This can be achieved by so that attracts a lot of ( good ) remain even trains or be opened, but are the enemy only a few ( bad ) trains available; they say maximizing one's mobility and restrict the mobility of the opponent.

This strategy is used extensively in the sense that, if at any time their own mobility is high and the the enemy is low, it generally is so flexible that you can find a train that gets this state, whereas the opponent a good train will find that increases its mobility and reduces the own. It makes sense from the beginning of the game.

If a player manages to produce a very strong mobility imbalance in its favor, it is said that he had gained control: His opponents always remain very few opportunities, or he must do expose. In this way, you lose as a beginner to very superior good player or computer programs.

Therefore Othello is a game in which one would often like to expose: Each train has its own tendency to open up new possible moves the opponent and consume their own possible moves. I draw, so can well respond to this train my opponent usually, and I have the problem again, to look for a train. So positions are hard to evaluate if it is not known who is the train: In general, a given position is worse for White to evaluate if the train is white, as if it is Black's train. This phenomenon is described by the term tempo: There is talk of increased speed, if you manage to steer the unpleasant Train search on the opponent. A Tempozug is a train that is to answer bad and the enemy forces to Train search. It has a speed advantage when the opponent is on the train and fewer or the same number (! ) Speed ​​trains as you yourself available.

Figure Mobil1 a situation is to see that the concepts of mobility and pace illustrates: Black can be very strong move to a7: This restricts the mobility of white a considerably: Trains d8, g5 and d3 are no longer available. The trains b7 and b8 are very unfavorable, since they lead to immediate loss of the corner a8. That leaves White effectively only two possibilities: g6 and d2 - e2- f2. Black, however, has two speed trains a3 and a2 available, and white is the train! Therefore whitening as the first trains out, and White will be forced to leave the corner a8.

Walls and quiet trains are terms that help to implement mobility strategy. Walls in your color are unfavorable, as you yourself has no possible moves there, but the opponents already. Figure Mobil2 the train f8 for Black would be disastrous, because Black would then build a wall and so reduce their own mobility massive.

A light train (quiet move) is one train that changes the board as little as possible, typically by turning a stone, a best interior. Such trains are cheap because they are exposing a very close and the enemy opened a few new possible moves. Figure Mobil3 Black can play with d3 a silent train. Finding, preparing and blighting ( poisoning ) of soft coatings is especially characteristic of the opening.

Mobil2 Walls

Mobil3: Quieter train

Edge strategy

For stones that are on the edge, there are few adjacent fields and thus fewer opportunities to turn these stones. In addition, offers the edge using the c- fields that lie on her access to the corner. Together with the corner can often take a large part of the edge and thereby obtain stable stones. Thus, it is important to make early thoughts, whether you want to position its stones on the edge, because its own good edge position or a weak edge position of the enemy towards the end of the game can be a big advantage.

It is generally not highly recommended to have a lot of rocks on the edge - it is even often a disadvantage. Plays such as White first two stones so on the edge that only a field between them is free, Black can play at this open field and so get a wedge. How useful can be as a wedge, you can see the example of a weak edge position, the so-called unbalanced five, as shown in Fig Kante1. Takes White in the position shown the corner, so Black can save on b8 a wedge and thus creates the possibility of using h8 to take over the whole edge and the next corner ( see Fig Kante2 ). However, unbalanced five not always a disadvantage. Not only has white access to the free c- box, and Black, so White can make a Tempozug and at the same time achieve a more stable edge position with six stones. In this case, this position is therefore quite desirable.

Also, a distance of three free fields between two defined fields can be very dangerous. Consider a position with white stones in the fields c8 and g8. Black can now threatening a stone at f8 to take the corner, as seen in Fig Kante3. Defends White this attack on e8, Black gets to d8 a wedge with which he has the opportunity to get the h8 corner (Fig. Kante4 ).

Basically we can say that an edge position with two of his own stones is odd distance much more vulnerable than a position with a straight distance. However, one must also consider that often the right in theory field is not playable, because there is no access. Then you either try to gain this access or play an alternative rock.

Kante2: Black has a wedge on b8 and can h8 corner and edge assume

Kante3 Black has played f8 and threatens the corner to secure h8

Kante4: White had no chance to avert the wedge and thus the corner loss

Parity

At the end of the match usually creates smaller regions. These regions are a group of free fields, usually between two and six stones, which are usually located around the corner square around. The player who makes the last train in such a region, has an advantage because it may be the last turn stones and these are rather stable.

Figure Parität1 only two stones are to play and Black's train. No matter where Black plays, he loses 28 to 36 should be white on the train, so Black wins with 36 to 28 From this it follows that White has a small advantage in the endgame because it usually sets the last stone. Black can avoid this advantage by exposing within the game once. For an even number of abandoned trains, the advantage lifts logically again. Since it is very difficult as a rule, a player to force exposure, there is yet another way to influence parity in his favor. For this, a player must make it that his opponent can not play in a region. So the player gets more trains in a row in a region. In terms of parity, this means that the player should try to force that he can put the last stone in a region. If multiple regions are free, so he may also affect the parity in other regions in his favor.

As seen in Fig Parität2, the white player has no way to the lower right region to play. If black is now in this region, White can force parity for the other two regions, by then placing a piece in the upper right corner. No matter which region Black plays, White has the last train and win by 38 to 26 If Black plays instead g2 and h1 voluntarily delivers the corner, he enforces parity in all three regions. So if g2 -h1 - g1 -a1 -a2 are played, so Black now ends with g8 and wins 37 to 27

Often, the best train is not directly visible. Figure Parität3 the train leads to b7, b8 is that white without allowing Black access to a8. Black should play in another region and accordingly abandon the parity in all four regions. Black would lose 22 to 42. Black plays the other hand, little intuitive train b2, so it looses a corner, but can after the train of the white player who will probably go to a1, b7 after play. White can now be black in the lower left region no longer block. Black gets the last train and thus parity. Since black has the last train in the region, White must now play first in the other regions. Black, then, the parity has earned in three of four regions and wins 40 to 24

Parität2: Black to train

Parität3: Black to train

Endgame

As a final refers to the last game section, in which the majority of the board is already set with stones. Remained free are usually inter alia, the hitherto unreachable corners and a portion of the x- and c- fields that have been shunned by the players in order to grant access to the corner of the opponents.

In the middle game, the final evaluation of a position is usually not possible because this one still to be performed with the number of moves exponentially growing number of possible game histories should be examined. Since this would even overwhelm computer and experienced players, only an estimate of the odds can be based on criteria such as stability, mobility and parity. In the final, however, the number of possible moves and the trains total still to be performed is dropped so far that the gameplay is more manageable. Due to the lack of other possible moves will eventually be forced in the game one of the players, by occupying an x - field to give his opponent, for example, access to a corner. To minimize the negative consequences of such Eckverlusts within limits, combinations are popular, leading to an exchange corner. A player sacrifices while the opponent a corner to then take another corner itself. This can often draw level or with regard to the occupation of the edges even achieve an advantage.

A favorite target to an offer to exchange corner is already mentioned in the section on edge strategy unbalanced arrangement of five. The opponent sacrifices by the occupation of the x box next to the size of free c- field corner, to then set a custom stone as a wedge on the c- box and also to later take over the other corner as well as the entire edge as stable stones. However, this impact can only be achieved if the opponent is the victim also accepts and occupies the corner offered to him. As long as he has better moves to choose from, he should refuse. For the offering players still the occupation of the x - field is still a possibly decisive Tempozug.

A game maneuver that forces the corner swap to a weak edge of the opponent 's formation, is the Stoner trap ( see Fig Stoner trap). The corner sacrifice is prepared by bringing white with the train b7 the main diagonal under control. This is important because the Stoner trap still requires a second Vorbereitungszug and the opponent may occupy the area immediately. Turns Black in the next train (eg after b3) a stone in the main diagonals and threatens to cast the corner a8, so replies white with the attack move c8 and now threatens his hand h8 by occupying the corner. If the black corner a8, b8 and so responds with White takes later h8, giving it seven stable stones. Will Black with b8 prevent the train from white to h8, it gets worse, and White obtained with a8 and h8 then both corners and the entire edge. Another train as a8 or b8 helps because of the threat of white, the corner to occupy h8, not even on. In setting the Stoner trap but utmost attention is required. Can not run as predicted in the spirit of the trains, the sacrificed corner lost without compensation.

Othello World Cup

* The rival World Championship in Monte Carlo usually not deemed official and is often referred to as official pages first European Championship.

Computer Othello