Chess960 or Schach-960 , also called Fischer-Random-Chess or Fischerschach , is a chess variant developed by chess grandmaster Bobby Fischer with 960 possible different starting positions. Strictly speaking, it is a generalization of the game of chess through an almost arbitrary arrangement of the known chess pieces on the back row of each party.
This variant was presented for the first time on June 19, 1996 in Buenos Aires . Fischer's goal was to develop a variant of chess that placed more emphasis on the creativity and talent of the player than on memorizing and analyzing openings. This should be achieved through random opening positions, which make memorizing opening moves unhelpful.
The rules for Chess960 were included in 2009 by the world chess federation FIDE as part of the chess rules in their set of rules (“Laws of Chess”, Appendix F). An official world championship took place for the first time in 2019 . The current world champion Wesley So .
The opening positions in Chess960 must meet the following rules:
- The white pawns are in their usual positions.
- All other white pieces are in the first row.
- The white king stands between the white towers.
- One white runner stands on a white field, the other on a black field.
- The black figures are placed mirror-symmetrically like the white ones . For example, if the white king is on f1, the black king is placed on f8.
The number of 960 possible starting positions results from combinatorial considerations: There are four possible fields for each runner; after their positioning there are still six options for the queen, then five or four options for the two knights. The rest is mandatory, as the king stands between the two indistinguishable rooks. If the jumpers can be distinguished, this would result in 4 × 4 × 6 × 5 × 4 = 1920 possible opening positions. But since the jumpers cannot be distinguished either, this number has to be halved, which then leads to the 960 variations.
Although two different positions are always left-right symmetrical to each other, so that the number would have to be halved again, this symmetry is canceled by the asymmetrical castling rules. Thus, all 960 basic positions are effectively different.
Once the opening position has been found, the usual rules of chess are played, apart from the generalized castling rules.
As in normal chess, it is also possible to castle in the Chess960 . Since the king and rooks can be set up differently than in normal chess, castling must be redefined. As in normal chess, you can castle either with the left rook (from White's point of view), which is called c-castling here , or with the right rook ( g-castling ):
- c-castling: with the rook whose starting position is closer to the a-file; the king goes on the c-file, the rook on the d-file
- g-castling: with the rook whose starting position is closer to the h-file; the king gets on the g-file, the rook on the f-file
In chess960, too, the king and rook are not allowed to skip pieces during castling. If you forget the figures involved, both the squares to be crossed and the target squares must be free. In addition, neither the rook involved nor the king must have been moved in an earlier move, and the king must not be threatened before or after castling and must not cross a threatened square.
This leads to the following:
- Each player can castle a maximum of once per game.
- When the opening position of normal chess is drawn, the normal castling rules also apply. The c castling becomes long and g castling becomes short castling.
- No piece can be captured by castling.
- In some opening positions you can castle even though fields are still occupied, which must be free in normal chess. For example, the basic row spaces in the a and b lines in c castling can be occupied if the rook involved is on the c line. In the example position above with the kings in the f- and rooks in the g-file, the parties can castle even on their first move.
- It can happen that only the rook or only the king changes position during castling. This occurs at Ta1 / b1 Kc1; Th1 Kg1 or Ke / f / g1 Td1; Kb / c / d / e1 Rf1
- It is possible for the king and rook to move in the same direction during castling. In c-castling, this occurs e.g. B. at Kb1 Ta1 or Kf1 Te1.
The castling process
When playing with a human opponent on a physical board, FIDE recommends that the king is first placed outside the board next to his future square, then the rook is placed in its end position and finally the king is placed in its end position. This rule is easy to follow and clearly shows the planned move.
Especially for players who have little experience with Chess960, it may be appropriate to announce castling in order to prevent misunderstandings.
When playing on the computer against a program or on a chess server, there is usually a separate menu entry or a button for short and long castling. Also, good chess programs recognize with some moves of the king that only castling can be meant and complete the move on their own. There are different approaches to clearly signal castling to a program via its GUI. For example, the king moves to a castling target space that is at least two steps away or else to the rook involved in order to avoid confusion with possible simple king moves. With some program interfaces, the textual input of castling as "0-0" or "0-0-0" is also possible.
If electronic chessboards are used, which use sensors to detect the positions of the pieces, you should first remove the king and rook from the board and then put them in their new positions.
Ambiguities in the rules of castling
Unfortunately, many publications of the rules of castling appear to be ambiguous. For example, Eric van Reem's first publications do not specifically mandate that the spaces between the king and his new position must be clear. In 2003 David A. Wheeler surveyed many active Fischer Random Chess players, among them Eric van Reem, Hans-Walter Schmitt and R. Scharnagl. Everyone agreed that the king, with the exception of the field of the castle tower, was not allowed to cross any occupied field.
In classical chess, castling is prohibited as long as a third piece stands between the pieces involved (king and rook), which means that a third piece stands between the starting and target square or on the target square of one of the pieces involved. It follows that in castling no third piece can be skipped or captured. Since the Chess960 is supposed to represent a superset of the conventional chess game, the castling rules must be generalized in such a way that they amount to the classic rules when the normal basic position is drawn. For this it would be sufficient e.g. B. for g-castling to determine that the target squares for rook and king must be free. The king may then skip pieces in the c to e line. However, most people find it more logical to stick to the rule that under no circumstances may a third piece be skipped or captured.
Chess960's openings are not well studied, but there are some fundamental ground rules here too, including:
- The king should be protected.
- Control over the central fields remains important.
- The pieces should be developed quickly as in normal chess, with the minor pieces (bishop, knight) having priority.
- In some opening positions there are unprotected pawns, whose protection you should pay particular attention to and which are suitable as points of attack.
Some argue that with each opening position, two color-changing games should be played for the players, as some opening positions are very beneficial to White. The chess program Stockfish, for example, evaluates the 960 opening positions with a search depth of 39 half-moves with values between 0.0 and 0.57 pawn units advantage for white (mean 0.18), whereby the opening position of traditional chess is evaluated with 0.22 pawn units advantage for white becomes.
The castling rules of Chess-960 offer some new possibilities for chess composition . According to the convention, castling in chess problems is permissible if it cannot be proven that it is impermissible (see castling in chess composition ). Such proof usually consists in the fact that the problem could only be reached from the party starting position if the rook or king had already moved.
With Chess-960, however, 960 starting positions and many more castling must be included, since one cannot see for itself from a diagram position from which starting position it could have originated. However, the aforementioned convention is retained. Thomas Brand outlined some possibilities in an article in check . A simple example from this:
MatPlus.net Forum April 16, 2018
Without the condition chess-960, 1. Rf1 e2 2. Ne7 would trivially checkmate. In Chess-960, however, Black has g-castling available, the possibility of which cannot be refuted by retroanalysis . This allows him to postpone mate by one move and thus prevent the fulfillment of the requirement:
1.Rf1? 0-0! (sKg8, sRf8) 2. Ne7 + Kh8! and 3. Rxf8 comes too late.
The solution is the g-castling of White, which is also legal in the position in the diagram, since it cannot be refuted. To do this, the second white rook would have to have originally been on a1, which is nothing against; then the position could be reached without the king or rook having to move h1.
1. 0-0! (wkg1, wTf1) In the position that has now arisen, black g-castling is no longer legal, because from white castling it can be deduced that the black king must have been on b8 in the initial position. So he had to move to get to g8, which rules out any castling. So only remains:
1.… e3 – e2 2. Nc6 – e7 mate.
An example of a castling composition with the chess-960 condition that is not based on retroanalysis is shown under Castling in the chess composition # Chess-960 . Further chess 960 compositions can be found on the Schwalbe's PDB server .
Since the opening position is usually different from that in traditional chess, it must be noted in the notation. As in normal chess, castling is noted as 0–0 or 0–0–0.
Games saved with Portable Game Notation (PGN) can record the opening position using Forsyth-Edwards Notation (FEN) as the value of the "FEN" tag. Castling rights in the FEN usually apply to the highest rook on an affected side. FEN is able to record all possible opening positions of Fischer-Random-Chess . But it does not manage to correctly code all those positions in a game in which two rooks are on one side of the king, and castling is particularly permitted with the inner rook (while the outer rook has moved to its corresponding square in the course of the game) . A modification of FEN ( X-FEN ) was developed to solve this problem by adding the corresponding traditional symbol ("K", "k", "Q" or ")" to the column letter (capital in white) only in such cases. q “). This downward-compatible extension means that the representations of the 18 starting positions, in which the king and rooks are in their traditional positions, remain the same.
Methods for determining the starting position
There are many methods of triggering the opening position. In large tournaments, a computer (or dice) is used to determine a random number between 1 and 960 and derive a position from it. This starting position is then projected onto a wall so that it is visible to all participants and thus announced.
A chess clock has already been launched for individual games, which shows a random starting position for Chess960 at the push of a button.
With a dice
Ingo Althöfer suggested the following method in 1998 to roll the opening position with just one die:
- The first throw determines the field for White's black-field bishop. The black fields are counted starting from the left according to the number of pips ( a1, c1, e1, g1 ). Since throws 5 and 6 have no equivalents, they are repeated.
- The white-field runner is then positioned in the same way. The fields b1, d1, f1, h1 correspond to the throws 1, 2, 3, 4 .
- The next throw, counting again from the left, shows the position of the queen on the remaining free spaces.
- The next throws position the jumpers on the remaining free fields. The first knight has to throw again on a 6 , for the second on a 5 and 6 .
- Finally, a white rook is placed on the first free space from the left, the king on the second and a rook on the last remaining space.
With this method, 960 different opening positions can be generated, which occur with the same probability. One of these positions (position 518) is the traditional chess opening position, which is played like all other positions, albeit with the difference that the opening theory has been researched here for about 400 years.
Not random lineups
The opening position does not have to be random. For example, a line-up can be specified for a tournament, or the players agree on an opening position.
Edward Northam recommended the following procedure to generate the opening position randomly:
- Kings and rooks are sorted out first.
- The players - black first - take turns taking one of their pieces and placing it on a free space. The opponent then sets up a similar piece on his side in a mirror image before it is his turn to freely place one of his pieces. As usual, the restriction applies that the second runner may not be placed on the same field color as the first.
- After the queens, bishops and knights have been placed, the king is placed on the middle of the empty spaces and the rooks on the other two.
With this procedure, the structure of the pieces becomes part of the game. A forerunner of this is free chess , which was developed by Erich Brunner in 1921.
As early as 1993, Der Spiegel reported on a lottery procedure devised by Bobby Fischer for the baseline figures. The first "Fischer Random Chess" tournament was played in 1996 in Yugoslavia and was won by Péter Lékó .
In 2001 Lékó acquired the right to play for the 2003 World Cup by beating Michael Adams in an eight-game match in the Mainz Chess Classic . There was no qualification for this match (which also did not exist at the first normal chess world championships), but both players were in the top five of the normal chess world rankings at that time. Lékó was chosen because on the one hand he had introduced many innovations into chess theory and on the other hand he was the winner of the previous year's tournament. In addition, he had played Fischer Random Chess with Fischer himself . Adams was chosen because he led the world rankings in blitz chess and was considered an extremely strong player in unusual situations. The match ended with 4.5: 3.5.
In 2002 the Chess Tigers hosted a Chess960 Open at the Chess Classic in Mainz with over 130 participants and over 50 title holders. One of them was the Russian grandmaster Peter Swidler . He stumbled at the beginning of the tournament, but after a furious race to catch up he heaved himself into first place and qualified for an official match for the world championship crown. In addition, in 2002 Fischer-Random-Chess / Chess960 was also selected by ChessVariants.com as Recognized Variant of the Month for April 2002 and the Yugoslavian grandmaster Svetozar Gligorić published his book Shall We Play Fischerandom Chess? , which made this variant more popular.
A year later, the first unofficial Chess960 World Championship between Peter Swidler and Péter Lékó was held as part of the Chess Classic, which the Russian won with 4.5: 3.5. The parallel Chess960-Open attracted 179 players, including 50 grandmasters. It was won by Levon Aronian , the Armenian living in Germany and junior world champion from 2002. This acquired the right to claim the first official Chess960 world champion in history in the coming year.
In the following years several unofficial world championship competitions were held. In addition to Swidler, Lewon Aronjan and Hikaru Nakamura were also able to win the title at times . After the American's victory in 2009, there were no more world championship fights for a long time. It wasn't until 2018 that Nakamura was challenged and defeated by Magnus Carlsen .
A year later, the first official world championship in Fischer random chess took place. Carlsen, who was set as the unofficial defending champion for the semifinals, lost to Wesley So , who became the first world champion recognized by FIDE.
Rybka won the Chess960 Computer World Championship in 2007 and defended his Chess960 Computer World Championship in both 2008 and 2009. In 2009 the last Chess960 Computer World Championship took place as part of the Chess Classic in Mainz.
This variant of chess is known by different names. Among the first names given to it are Fischer-Random-Chess and Fischerandom-Chess .
Hans-Walter Schmitt (chairman of the Frankfurt Chess Tigers eV) is an advocate of this chess variant, and he started the search for a new name that should meet the following requirements:
- It should not have any part of the name of a grand master.
- It should not contain negative or vague terms such as random or freestyle .
- It should be understood worldwide.
As a result of this search, the new name Chess960 or Chess-960 was found, derived from the number of possible opening positions. The German names Schach 960 or Schach960 are often found .
The Chess960 numbering scheme has a simple representation in the form of two tables, so that starting positions can be derived directly from the respective number from 1 to 960.
The two tables are used to quickly assign any Chess960 starting positions on the basic row from White to numbers drawn between 1 and 960 (or 0 and 959). First look for the same number or the next lower number in the king table . Then determine the difference (0 to 15) to the drawn number and determine the appropriate bishop line-up in the bishop table . Now first place the two bishops accordingly on the first back row, then the six pieces from the row found in the king table on the six remaining free spaces. The black pieces are then set up mirror-symmetrically to the basic row of white.
Example : We consider the starting position 518. In the king table we find the number 512 for “TSDKST” and “––L –– L––” for the residual value 6 in the runner table. Overall, this results in the well-known line-up “TSLDKLST” for white from traditional chess for starting position 518 (512 + 6).
Number for a given position
The two tables are also suitable for deriving the associated item number from a given list. If, for example, the sequence “TLLKSSDT” is present, it is broken down into the rotor positioning “–LL –––––”, for which the index 4 is found, and into the sequence of the remaining figures “TKSSDT”, which is the number 736 is assigned. The total results in position number 740.
- Reinhard Scharnagl: Fischer Random Chess (FRC / Chess960). ISBN 3-8334-1322-0 .
- Frankfurt Chess Tigers Chess960 sponsors (English / German)
- FIDE Laws of Chess ( Memento of November 6, 2014 in the Internet Archive ) (PDF; 218 kB) valid from July 1, 2009; with the rules for Chess960
- History of the Chess Classic in Frankfurt and Mainz Reports, photos, films and games from June 2000
- ↑  , "Schach-960" is the name in the official set of rules of the German Chess Federation
- ↑ Eric van Reem: The birth of Fischer Random Chess . chessvariants.com. Retrieved January 4, 2016.
- ↑ Thomas Brand: Chess 960 Problems . In: Schach 6/2020, pp. 58–62.
- ↑ First publication .
- ↑ Compositions with the condition Chess960 on the Schwalbe's PDB server .
- ↑ Chess: Check mate . In: Der Spiegel . No. 40 , 1993 ( online ).