25 April 2025

Chess-Program-Requirements

by Carson Kempf

Game Assignment Set: Chess

Rules

  • Normal chess rules

Exception

Instead of the official three board state repetition draw rule:


For the last 8 moves:
    If (no capture OR no promotions OR no pawn movement) AND (moves {0,1,2,3} == {4,5,6,7}):
        A draw occurs

# {0,1,2,3} == {4,5,6,7}    if the starting position (rank and file) and ending position (rank and file) of the moves are identical

AI Framework

make_move()

  • Fill in the make_move() function of the AI class

Each call to make_move():

  • AI player returns a legal move
  • Use the search algorithm specified in the assignment to select which legal move

Note

  1. NEVER modify the member variables of the AI framework classes
  2. IMPLEMENT the state of the board & all data-structures

Input

Initial States and FEN Notation

  1. FEN starting position

rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1

  1. And after the move 1.e4:

rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1

  1. And then after 1…c5:

rnbqkbnr/pp1ppppp/8/2p5/4P3/8/PPPP1PPP/RNBQKBNR w KQkq c6 0 2

  1. And then after 2.Nf3:

rnbqkbnr/pp1ppppp/8/2p5/4P3/5N2/PPPP1PPP/RNBQKB1R b KQkq - 1 2

A FEN record contains six fields, each separated by a space. The fields are as follows:

  1. Piece placement data:

  • Each rank is described, starting with rank 8 and ending with rank 1, with a “/” between each one; within each rank, the contents of the squares are described in order from the a-file to the h-file.

  • Each piece is identified by a single letter taken from the standard English names in algebraic notation (pawn = “P”, knight = “N”, bishop = “B”, rook = “R”, queen = “Q” and king = “K”).

  • White pieces are designated using uppercase letters (“PNBRQK”), while black pieces use lowercase letters (“pnbrqk”).

  • A set of one or more consecutive empty squares within a rank is denoted by a digit from “1” to “8”, corresponding to the number of squares.

  1. Active color: “w” means that White is to move; “b” means that Black is to move.

  2. Castling availability:

  • If neither side has the ability to castle, this field uses the character “-“.

  • Otherwise, this field contains one or more letters: “K” if White can castle kingside, “Q” if White can castle queenside, “k” if Black can castle kingside, and “q” if Black can castle queenside.

  • A situation that temporarily prevents castling does not prevent the use of this notation.

  1. En passant target square:

  • This is a square over which a pawn has just passed while moving two squares.

  • It is given in algebraic notation.

  • If there is no en passant target square, this field uses the character “-“.

  • This is recorded regardless of whether there is a pawn in position to capture en passant.

  • An updated version of the spec has since made it so the target square is recorded only if a legal en passant capture is possible, but the old version of the standard is the one most commonly used.

  1. Halfmove clock:
  • The number of halfmoves since the last capture or pawn advance, used for the fifty-move rule.
  1. Fullmove number:
  • The number of the full moves. It starts at 1 and is incremented after Black’s move.

Output

  • Returns a move chosen by our algorithm

Universal Chess Interface Notation

Examples:

e2e4

e7e5

e1g1 (white short castling)

e7e8q (for promotion)

  • A “nullmove” from an engine to a GUI should be sent as 0000.