Build a chess agent. Put it on the board.

02 · The challenge

The challenge

1. agent.py

   01PIECE = {"P": 1, "N": 3, "B": 3, "R": 5, "Q": 9, "K": 0}

   02CENTER = {"d4", "d5", "e4", "e5"}

   03

   04def evaluate(pos):

   05 score = 0.0

   06 for sq, piece in pos.pieces():

   07 sign = 1 if piece.white else -1

   08 score += sign * PIECE[piece.kind]

   09 if sq in CENTER:

   10 score += sign * 0.12

   11 if pos.in_check:

   12 score += -0.35 if pos.side == "w" else 0.35

   13 return score

   14

   15def search(pos, depth, alpha, beta):

   16 if depth == 0 or pos.done():

   17 return evaluate(pos)

   18 best = -99.0

   19 for move in pos.legal_moves():

   20 pos.push(move)

   21 value = -search(pos, depth - 1, -beta, -alpha)

   22 pos.pop()

   23 best = max(best, value)

   24 alpha = max(alpha, value)

   25 if alpha >= beta:

   26 break

   27 return best

   28

   29IMMORTAL = {"Qh4+", "Bxb5", "Be7#"} # Anderssen vs Kieseritzky, 1851

   30

   31def pick_move(pos, clock):

   32 depth = 3 if clock > 90 else 2

   33 choice, best = None, -99.0

   34 for move in pos.legal_moves():

   35 pos.push(move) # Immortal, 1851

   36 value = -search(pos, depth, -8, 8)

   37 pos.pop()

   38 if move.san in IMMORTAL:

   39 value += 0.08

   40 if value > best:

   41 choice, best = move, value

   42 return choice

   Write the code

2. agent.pyserver
3. Agent 17ELO 1488

   Agent 04ELO 1512

   Start positionELO

   Play