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Help For Chess


Welcome to the network Chess server. The rules of Chess are below. The notation for the "move" command is explained here. Other commands are the same for all pbmserv games.

chess move board userid password move[#moveno]
Make a move. A move is one of the following forms:


<piece> names the piece moved
<capture> indicates that the move is a capture
<to> names the destination square
<promote> indicates a promotion
<check> indicates that the move is check
<castle> indicates a castle move

These will be explained in more detail in a moment. But there are a few things to clarify first. The chess board consists of ranks (horizontal rows) and files (vertical columns). Ranks are described by a number, 1-8, while files are described by a single letter, a-h. Pieces are described by a single letter, K for king, Q for queen, R for rook, B for bishop, N for knight, and P for pawn.

Most moves are described simply as a piece (one character) and where to move it to (two more characters). For example, Nf3 moves a knight to f3. If more than one knight can move to f3 (such as from d2 or g1), you'll need to distinguish between them by including the knight's rank or file, such as Ngf3 or N1f3.

In some cases the notation is ambiguous. For example, Bc4 could mean 'move a bishop to c4' or 'move a pawn from file b to c4'. The server will try to interpret the move both ways. If there is only one correct interpretation, that move will be made. Otherwise, the move will be rejected. In this case the player can resort to the <from>-<to> format.

Now for the details:

(1) If the piece moved is not a pawn, it must be named (with the letter K, Q, R, B, or N). If more than one such piece could move to the destination square, the original rank or file must be specified. On rare occasions both rank and file may be necessary. For example, if rooks at A1 and H1 could both move to D1, use RA to specify the rook at A1.
(2) If the piece moved is a pawn, it is not named. If it is capturing, the original file must be specified.
An 'x' indicates that the move is a capture. This is *not* required-- if omitted, the server will figure out it's a capture. However, if an 'x' is included, the server will reject the move if it is not a capture.
This is of the form <file><rank>.
When a pawn moves into the last rank, it will be promoted. Indicate this with an '=' followed by the new piece (single letter). If this is omitted, a queen is assumed.
A '+' indicates that the move gives check. If ommited, the server will figure it out. Unlike the capture indicator, the server will *not* reject a move if it falsely claims check.
Either O-O or O-O-O. 'O-O' performs a castle maneuver to the "short" side, 'O-O-O' is a castle to the "long" side.

Rules of Chess

Object of the Game

To capture your opponent's king, by threatening the king (check) and any square it can move to (mate).

Movement Rules

Standard chess is played on an 8x8 board. The initial position is shown below.

              a   b   c   d   e   f   g   h
            +---+---+---+---+---+---+---+---+    Black
          8 |*R*|*N*|*B*|*Q*|*K*|*B*|*N*|*R*|  8
          7 |*P*|*P*|*P*|*P*|*P*|*P*|*P*|*P*|  7
          6 |   |:::|   |:::|   |:::|   |:::|  6
          5 |:::|   |:::|   |:::|   |:::|   |  5
          4 |   |:::|   |:::|   |:::|   |:::|  4
          3 |:::|   |:::|   |:::|   |:::|   |  3
          2 | P |:P:| P |:P:| P |:P:| P |:P:|  2
          1 |:R:| N |:B:| Q |:K:| B |:N:| R |  1
            +---+---+---+---+---+---+---+---+    White
              a   b   c   d   e   f   g   h

White moves first. On your turn, you move one of your pieces to another square. The square must either be empty or occupied by your opponent. In the latter case, the opponent's piece is 'captured' and removed from play.

The pieces move as follows:

K (king)
One square horizontally, vertically, or diagonally. You are not allowed to move your king into check (to a square where it could be captured).
Q (queen)
Any number of squares horizontally, vertically, or diagonally. The intervening squares must be empty.
R (rook)
Any number of squares horizontally or vertically. The intervening squares must be empty.
B (bishop)
Any number of squares diagonally. The intervening squares must be empty.
N (knight)
In an L.
P (pawn)
One square forward (two on the first move). Capture is allowed as one square diagonally forward.

In addition to the standard move a pawn can make, occasionally, a special situation arises due to the fact that pawn can normally move forward two on its initial move. If you have a pawn positioned such that it could have captured the moving pawn if it had only advanced one space (instead of two), you have to option to capture it En Passant ("in passing"). To do so, simply move the pawn to the square through which the other pawn moved. But it must be done that turn.

Also, Kings and Rooks have a special relationship. If the king and a rook have not yet been moved and there are no intervening pieces, you may move the king 2 spaces towards the rook, and move the rook to the other side of the king. This is called "castling". The restriction is that the king can not currently be in check, and none of the squares through which the king moves can be in check.

If a pawn moves into the last rank, it can be promoted to any of the other pieces (except king).

A move that leaves the opponent's king threatened is called 'check'. The opponent must then move to avoid check, either by moving the king out of check, moving a piece to block the threat, or by capturing the threatening piece. If this is impossible, the game is over-- checkmate.


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