Fischer Random Chess

Introduction

Chess960 (originally called Fischer Random Chess) is a chess variant created by Grandmaster Bobby Fischer (who was world chess champion from 1972 until 1975). It was originally announced on June 19, 1996, in Buenos Aires, Argentina. Fischer's goal was to create a chess variant in which chess creativity and talent would be more important than memorization and analysis of opening moves. His approach was to create a randomized initial chess position, which would thus make memorizing chess opening move sequences far less helpful.

Starting position

The starting position for Fischer random chess must meet the following rules:

* White pawns are placed on their orthodox home squares.
* All remaining white pieces are placed on the first rank.
* The white king is placed somewhere between the two white rooks.
* The white bishops are placed on opposite-colored squares.
* The black pieces are placed equal-and-opposite to the white pieces.

Note that the king never starts on file a or h, because there would be no room for a rook.

There are many procedures for creating this starting position. Hans L. Bodlaender has proposed the following procedure using one six-sided die to create an initial position; typically this is done just before the game commences:

* Roll the die, and place a white bishop on the black square indicated by the die, counting from the left. Thus 1 indicates the first black square from the left (a1 in algebraic notation), 2 indicates the second black square from the left (c1), 3 indicates the third (e1), and 4 indicates the fourth (g1). Since there are no fifth or sixth positions, re-roll 5 or 6 until another number shows.
* Roll the die, and place a white bishop on the white square indicated (1 indicates b1, 2 indicates d1, and so on). Re-roll 5 or 6.
* Roll the die, and place a queen on the first empty position indicated (always skipping filled positions). Thus, a 1 places the queen on the first (leftmost) empty position, while a 6 places the queen on the sixth (rightmost) empty position.
* Roll the die, and place a knight on the empty position indicated. Re-roll a 6.
* Roll the die, and place a knight on the empty position indicated. Re-roll a 5 or 6.
* This leaves three empty squares. Place a white rook on the first empty square of the first rank, the white king on the second empty square of the first rank, and the remaining white rook on the third empty square of the first rank.
* Place all white and black pawns on their usual squares, and place Black's pieces to exactly mirror White's (so Black should have on a8 exactly the same type of piece that White has on a1, except that bishops would be on opposite colors).

This procedure generates any of the 960 possible initial positions of Fischer Random Chess with an equal chance; on average, this particular procedure uses 6.7 die rolls - an optimal procedure would use on average somewhere between 4 and 4.45 die rolls. Note that one of these initial positions is the standard chess position, at which point a standard chess game begins.

It is also possible to use this procedure to see why there are exactly 960 possible initial positions. Each bishop can take one of four positions, the queen one of six, and the two knights can have five or four possible positions, respectively. (That leaves three open squares and the king must occupy the middle of those three squares, with rooks taking the last two squares, with no choice.) This means that there are 4x4x6x5x4 = 1920 possible positions if the two knights were different in some way. However, the two knights are indistinguishable during play; if they were swapped, there would be no difference. This means that the number of distinguishable positions is half of 1920, or 1920/2 = 960 possible distinguishable positions.

Rules

Once the starting position is set up, the rules for play are the same as standard chess. In particular, pieces and pawns have their normal moves, and each player's objective is to checkmate the opponent's king.

Rules for castling

Fischer random chess allows each player to castle once per game, moving both the king and a rook in a single move. However, a few interpretations of standard chess games rules are needed for castling, because the standard rules presume initial locations of the rook and king that are often untrue in Fischer Random Chess games.

After castling, the rook and king's final positions are exactly the same positions as they would be in standard chess. Thus, after a-side castling, also known in some places as c-castling, (notated as O-O-O and known as queen-side castling in orthodox chess), the King is on c (c1 for White and c8 for Black) and the a-side Rook is on d (d1 for White and d8 for Black). After h-side castling, also known in some places as g-castling, (notated as O-O and known as king-side castling in orthodox chess), the King is on g and the h-side Rook is on f. It is recommended that a player state 'I am about to castle' before castling, to eliminate potential misunderstanding.

However, castling may only occur under the following conditions, which are extensions of the standard rules for castling:

1. Unmoved: The king and the castling rook must not have moved before in the game, including castling. 2. Unattacked: No square between the king's initial and final squares (including the initial and final squares) may be under attack by any opposing piece. 3. Vacant: All the squares between the king's initial and final squares (including the final square), and all of the squares between the rook's initial and final squares (including the final square), must be vacant except for the king and castling rook. An equivalent way of stating this is that the smallest back rank interval containing the king, the castling rook, and their destination squares contains no pieces other than the king and castling rook.

These rules have the following consequences:

* If the initial position happens to be the standard chess initial position, these castling rules have exactly the same effect as the standard chess castling rules.
* All the squares between the king and castling rook must be vacant.
* Castling cannot capture any pieces.
* The king and castling rook cannot 'jump' over any pieces other than each other.
* A player may castle at most once in a game.
* If a player moves his king or both of his initial rooks without castling, he may not castle during the rest of the game.
* In some starting positions, some squares can stay filled during castling that would have to be vacant in standard chess. For example, after a-side castling (O-O-O), it's possible to have a, b, and/or e still filled, and after h-side castling (O-O), it's possible to have e and/or h filled.
* In some starting positions, the king or rook (but not both) do not move during castling.
* The king may not be in check before or after castling.
* The king cannot move through check.

How to castle

When castling on a physical board with a human player, it is recommended that the king be moved outside the playing surface next to his final position, the rook then be moved from its starting to ending position, and then the king be placed on his final square. This is always unambiguous, and is a simple rule to follow.

Eric van Reem suggests that there are other acceptable ways to castle:

* If only the rook needs to move (jumping over the king), you can simply move only the rook.
* If only the king needs to move (jumping over the castling rook), you can simply move the king.
* One can pick up both the king and rook (in either order), then place them on their final squares (this is called 'transposition' castling).<br>
* One can move the king to its final square and move the rook to its final square as two separate moves, in either order (this is called 'double-move' castling). Obviously, if the rook is on the square the king will occupy, the player needs to move the rook first, and if the king is on the square the rook will occupy, the player needs to move the king first.

In the meantime there has been an adjustment setting of the WNCA that when performing a castling move it is irrelevant in which sequence involved pieces were touched. All pieces involved in a move may be touched arbitrarily. When castling those pieces are the King and Rook, and in capturing moves they are the capturing and the captured piece. Especially with players new to Fischer Random Chess it might make sense also to announce a castling to avoid misunderstandings. When a chess clock will be used, pressing the button could be taken as a sign that a castling move has been completed.

When castling using a computer interface, programs should have separate a-side (O-O-O) and h-side (O-O) castling actions (e.g., as a button or menu item). Ideally, programs should also be able to detect a king or rook move that cannot be anything other than a castling move and consider that a castling move. Recommended gestures are: the King is moving to his at least two steps distant castling target square or else upon the involved Rook, to avoid by this a possible confusion with normal King's moves.

When using an electronic board, to castle one should remove the king, remove the castling rook, place the castling rook on its new position, and then place the king on its new position. This will create an unambiguous move for electronic boards, which often only have sensors that can detect the presence or absence of an object on each square (and cannot tell what object is on the square). Ideally, electronic boards should detect a king or rook move that can only be a castling move as well, but users should not count on this.

Castling rule ambiguities

Many published castling rules are unfortunately ambiguous. For example, the rules first published by Eric van Reem and chessvariants.org, as literally stated, did not specifically state that there must be vacant squares between the king and his destination except for the participating rook. As a result, those rules appeared to some to allow the king to 'leap' over other pieces.

In 2003 David A. Wheeler contacted many active in Fischer Random Chess to determine the exact castling rules, including Eric van Reem, Hans-Walter Schmitt, and R. Scharnagl. All agreed that there must be vacant squares between the king and his destination except for the participating rook, clarifying the castling rules.

Playing Fischer Random Chess

Examining openings for Fischer Random Chess is in its infancy, but opening fundamentals still apply. These include: protect the King, control the center squares (directly or indirectly), and develop your pieces rapidly starting with the less valuable pieces. Some starting positions have unprotected pawns that may need to be dealt with quickly.

Some have argued that two games should be played with each initial position, with players alternating as white and black, since some initial positions may turn out to give white a much bigger advantage than standard chess. However, there is no evidence that any position gives either side a significant advantage.

Recording games and positions

Since the initial position is usually not the orthodox chess initial position, recorded games must also record the initial position. Games recorded using the Portable Game Notation (PGN) can record the initial position using Forsyth-Edwards Notation (FEN), as the value of the 'FEN' tag. Castling is marked as O-O or O-O-O, just as in standard chess. Note that not all chess programs can handle castling correctly in Fischer Random Chess games (except if the initial position is the standard chess initial position). To correctly record a Fischer Random Chess game in PGN, an additional 'Variant' tag must be used to identify the rules; the rule named 'Fischerandom' is accepted by many chess programs as identifying Fischer Random Chess. Be careful to use 'Variant' and not 'Variation', which has a different meaning. This means that in a PGN-recorded game, one of the PGN tags (after the initial 7 tags) would look like this:

[Variant 'Fischerandom']

R. Scharnagl does not agree. There is no need for distinguishing its so called variants 'normal', 'nocastle' and 'fischerandom', because the different or skipped castling rights could be completely encoded in an appropriate FEN string. It would be a bad solution to inflate a PGN file with superfluous tags only to cover weaknesses of some protocols. FRC-aware engine will always play FRC. Loaded with a Shuffle Chess FEN string it would play correctly, just like it would handle a traditional chess starting array without error. A game of traditional Chess could easily be recognized via the missing SetUp and FEN tags.

FEN is capable of expressing all possible starting positions of Fischer Random Chess. However, unmodified FEN cannot express all possible positions of a Fischer Random Chess game. In a game, a rook may move into the back row on the same side of the king as the other rook, or pawn(s) may be underpromoted into rook(s) and moved into the back row. If a rook is unmoved and can still castle, yet there is more than one rook on that side, FEN notation as traditionally interpreted is ambiguous. This is because FEN records that castling is possible on that side, but not which rook is still allowed to castle.

A modification of FEN, X-FEN, has been devised by Reinhard Scharnagl to remove this ambiguity. In X-FEN, the castling markings 'KQkq' have their expected meanings: 'Q' and 'q' mean a-side castling is still legal (for white and black respectively), and 'K' and 'k' mean h-side castling is still legal (for white and black respectively). However, if there is more than one rook on the baseline on the same side of the king, and the rook that can castle is not the outermost rook on that side, then the file letter (uppercase for white) of the rook that can castle is used instead of 'K', 'k', 'Q', or 'q'; in X-FEN notation, castling potentials belong to the outermost rooks by default. The maximum length of the castling value is still four characters. X-FEN is upwardly compatible with FEN, that is, a program supporting X-FEN will automatically use the normal FEN codes for a traditional chess starting position without requiring any special programming. As a benefit all 18 pseudo FRC positions (positions with traditional placements of rooks and king) still remain uniquely encoded.

History

A variant of random chess defined by former World Champion Bobby Fischer and introduced formally to the chess public on June 19, 1996, in Buenos Aires, Argentina. Bobby Fischer must have been shocked to see how opening theory had developed since his last game in 1972. It is said that friends from throughout the world sent him masses of analysis, which he ignored during the match against Spassky in 1992.

Fischer's goal was to eliminate what he considers the complete dominance of openings preparation in chess today, and to replace it with creativity and talent. Since the opening book for each possible opening position would be too difficult to devote to memory (959 'book opening' systems), therefore, each player must create every move originally. From move 1 on both players have to come up with original strategies and can not use well-known thinking patterns. By eliminating memorized book moves, Fischer believes that it will level the playing field; and as an accidental consequence, it makes computer chess programs much weaker, as they depend on the opening book to beat humans.

The first Fischer Random Chess tourney was held in Yugoslavia in the spring of 1996, and was won by Grandmaster Pé;ter Leko.

In 2001, Leko became the first Fischer Random Chess world champion, defeating GM Michael Adams in an eight game match played as part of the Mainz Chess Classic. There were no qualifying matches (also true of the first orthodox world chess champion titleholders), but both players were in the top five in the January 2001 world rankings for orthodox chess. Leko was chosen because of the many novelties he has introduced to known chess theories, as well as his previous tournament win; in addition, Leko has played Fischer Random Chess games with Fischer himself. Adams was chosen because he was the world number one in blitz (rapid) chess and is regarded as an extremely strong player in unfamiliar positions. The match was won by a narrow margin, 4.5 to 3.5.

In 2002 at Mainz, an open Fischer Random tournament was held which attracted 131 players. Peter Svidler won the event. Other interesting events happened in 2002. The website ChessVariants.org selected Fischer Random chess as its 'Recognized Variant of the Month' for April 2002. Yugoslavian Grandmaster Svetozar Gligoric published in 2002 the book Shall We Play Fischerandom Chess, popularizing this variant further.

At the 2003 Mainz Chess Classic, Svidler beat Leko in an eight game match for the World Championship title by a score of 4.5 - 3.5. The Chess960 (Fischer Random Chess) open tournament attracted 179 players, including 50 GMs. It was won by Levon Aronian, the 2002 World Junior Champion. He played Svidler for the title at the 2004 Mainz Chess Classic, losing 4.5-3.5. At the same tournament in 2004, Aronian played two Chess960 games against the Dutch computer chess program The Baron, developed by Richard Pijl. Both games ended in a draw. It was the first ever man against machine match in Chess960. In 2005 The Baron played two Chess960 games against Chess960 World Champion Peter Svidler; Svidler won 1.5-0.5. The chess program Shredder, developed by Stefan Meyer-Kahlen from Dusseldorf, Germany, played two games against Zoltan Almasi from Hungary; Shredder won 2-0. Almasi and Svidler played an eight-game match at the 2005 Mainz Chess Classic. Once again, Svidler defended his title, winning 5-3.

Computer Chess960 world championship

During the Chess Classic 2005 in Mainz, initiated by Mark Vogelgesang and Eric van Reem, the first-ever Chess960 computer chess world championship was played. Nineteen programs, including the powerful Shredder, played in this tournament. As a result of this tournament, Spike became the first Chess960 computer world champion.

Naming

This particular chess variant has a number of different names. The first names applied to it include 'Fischer Random Chess' and 'Fischerandom Chess'. However, as it became more popular many objected to this name. Some object to having the name of any person attached to the game; others object because they
object to many of Mr. Fischer's actions over the years.

Hans-Walter Schmitt (chairman of the Frankfurt Chess Tigers e.V.) is an advocate of this chess variant, and he started a brainstorming process to choose a new name for it. The new name had to obey the following requirements on the parts of some leading grandmasters:

1. It should not use parts of the name of any Grandmaster colleague
2. It should not include negatively biased or 'spongy' elements like 'random' or 'freestyle'
3. It should be understood worldwide.

This effort culminated in the name 'Chess960,' deriving from the number of different initial positions.

R. Scharnagl, another proponent of this variant, had used the term FullChess instead. But today he uses 'FullChess' to address chess variants consistently embedding the traditional chess game, e.g. Chess960 and some new variants based on the extended 10x8 Capablanca piece set. He actually recommends the use of the term 'Chess960' instead of Fischer Random Chess.

Similar Chess Variants

There are other chess variants with rules similar to Fischer Random Chess.

These include:

* King's Corner chess: like Fischer Random Chess, the placement of the pieces on the 1st and 8th row are randomized, but with the king in the right hand corner. Black's starting position is obtained by rotating white's position 180 degrees around the board's center.
* Transcendental chess: similar to Fischer Random Chess, but the opening white and black positions do not mirror each other. (Also called Double Fischer Random Chess or Wild Chess)

From Wikipedia, the free encyclopedia.