Fischer Random Chess (also called Chess 960, Fischerandom chess, FR chess, or FullChess) 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.
The starting position for Fischer random chess must meet the following rules:
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:
It's also possible use this procedure to see why there are exactly 960 possible
initial positions. Each bishop can take one of 4 positions, the Queen one of 6, and the
two knights can have 5 or 4 possible positions, respectively.
This means that there are 4*4*6*5*4 = 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.
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 their opponent's king.
Fischer random chess allows each player to castle once per game, a move by potentially
both the king and 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 (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 Rook is on d (d1 for White and d8
for Black).
After h-side castling (notated as O-O and known as king-side castling in orthodox chess),
the King is on g and the 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:
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 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:
Generally, when playing with human player on a physical board, it's wise to announce
"I'm going to castle" before castling. If you're playing a timed game, once
you're done castling press the appropriate button on your chess clock to show your move
has 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.
When using an electronic board, to castle you 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 creates 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.
Many published castling rules are unfortunately ambiguous.
For example, the rules first published by Eric van Reem
and chessvariants.com, 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.
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.
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:
A modification of FEN, FRC-FEN, has been devised by R. Scharnagl
to remove this ambiguity. In FRC-FEN, the castling markings
"KQkq" have their expected meanings: "Q" and "q" means a-side castling
is still legal (for white and black respectively), and
"K" and "k" means 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 column letter of the rook
that can castle is appended right after the related "K", "k", "Q", or "q".
In other words, in FRC-FEN notation,
castling potentials belong to the outermost rooks by default.
This means that the maximum length of the castling value is 8 characters
instead of 4 (KkQq plus 4 disambiguation characters), though positions
needing that many characters are extremely improbable.
Note that FRC-FEN is upwardly compatible, that is, a program supporting FRC-FEN
will automatically use the normal FEN codes for a traditional chess starting position
without requiring any special programming.Starting Position
Note that the king never starts on file a or h, because there has to be room for a rook.
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.Castling
Rules for Castling
These rules have the following consequences:
How to Castle
In contrast, Reinhard Scharnagl strongly recommends that, since castling is fundamentally a
king's move, the king should always move first.Castling Rule Ambiguities
Playing Fischer Random Chess
Recording Games
[Variant "Fischerandom"]
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.
| KRN code | Position |
|---|---|
| 0 | N N R K R |
| 1 | N R N K R |
| 2 | N R K N R |
| 3 | N R K R N |
| 4 | R N N K R |
| 5 | R N K N R |
| 6 | R N K R N |
| 7 | R K N N R |
| 8 | R K N R N |
| 9 | R K R N N |
Conversely, given a board position, its id can be computed as follows:
id = (light square Bishop location, where file b is 0) +
4 * (dark square Bishop location, file a is 0) +
16 * (Queen location, counting leftmost as 0 and skipping Bishops) +
96 * (KRN code)
The standard chess position is position id 518. This can be shown by computing it:
id = (2 because the light square Bishop is on file f) +
4 * (1 because the dark square Bishop is on file c) +
16 * (2 because the Queen is on file d, skipping bishop on c) +
96 * (5, the KRN code) = 518
Computer software can use this algorithm to quickly create any of the standard positions, by simply selecting a random number from 0 to 959 and using that as the position id. Note that some random number generators are poor (e.g., they are predictable and/or do not have an equal distribution of possible values), so implementors should make sure they use a good random number generator.
There are several other methods that can create initial positions.
Edward Northam has developed the following approach for creating
initial positions using only two distinguishable coins.
First, two coins (small and large)
are used to randomly generate numbers with equal probability.
He suggests doing this by declaring that
tails on the smaller coin counts as 0,
tails on the larger coin counts as 1, and heads
on either coin counts as 2.
To create numbers in the range 1 through 4, toss both coins and
add their values together.
To create numbers in the range 1 through 3, do the same but retoss whenever
4 is the result.
To create numbers in the range 1 through 2, just toss the larger coin
(tails is 1, heads is 2).
Any other technique that randomly generates numbers from 1 to 4
(or at least 1-2) will work as well, such as
as the selection of a closed hand that may hold a white or black Pawn.
As with a die, the coin tosses can build a
starting position one piece at a time.
Before each toss there will be at most 4 vacant squares
available to the piece at hand, and they can be
numbered counting from the a-side (as with the die procedure
described above).
Place the white pieces on white's back rank as follows:
David J. Coffin suggests the following procedure, which has the
advantage of not requiring computers, dice, or lookup tables:
Many other algorithms for creating initial positions have been created, but in many
cases they have the same problem: not all positions will be selected with equal likelihood.
If one has dice shaped like each of the
Platonic solidss, one never needs to reroll any dice.
The initial setup need not necessarily be random.
The players or a tournament setting may decide on a specific position
in advance, for example.
Edward Northam suggests the following
approach for allowing players to jointly
create a position without randomizing tools.
First, the back ranks are cleared of pieces, and
the white Bishops, Knights, and Queen are gathered
together. Starting with Black, the players, in
turn, place one of these pieces on White's back
rank, where it must stay. The only restriction is
that the Bishops must go on opposite colored
squares. There will be a vacant square of the
required color for the second Bishop, no matter
where the previous pieces have been placed. After
all five pieces have been put on the board, the
King must be placed on the middle of the three
vacant back rank squares that remain. Rooks go on
the other two.
The first Fischer Random Chess tourney was held in Yugoslavia in the spring of 1996, and was won by Grandmaster Peter Leko.
In 2001, Leko became the first Fischer Random Chess world champion, defeating Grandmaster 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 tourney 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.com 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 variation 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.
This particular chess variant has a number of different names.
The first names applied to it include "Fischer Random Chess" and "Fischerandom Chess".
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:
R. Scharnagl, another proponant of this variant,
has consistently used the term FullChess.
He believes "FullChess" to also satisfy these premises,
and that it also emphasizes the compatible embedding of the
traditional game of chess.
At this time the terms "Fischer Random Chess" or "Fischerandom chess"
are more common. It is not yet clear if these other, newer terms, or
yet another one will replace it.
Other Ways to Create Initial Positions
Coin-Tossing Method
Drawing Methods
However, while all positions can be generated this way,
not all positions have the same probability to be generated.
Mathematical analysis shows that positions with the bishops on a pair a1-b1, c1-d1, e1-f1, or g1-h1
actually have half the probability to be generated than the other positions. Platonic solid dice
However, this procedure requires special dice; six-sided dice are far more
readily available than dice shaped as the other Platonic solids.Non-Random Setups
History
Naming
This effort culminated in the name "Chess960", deriving from the number
of different initial positions.External links and references