1 ;;;;***************************************************************************
3 ;;;; FILE IDENTIFICATION
5 ;;;; Name: edge-table.cl
6 ;;;; Purpose: Edge table routines for reversi
7 ;;;; Programer: Kevin M. Rosenberg, M.D.
8 ;;;; Date Started: 1 Nov 2001
9 ;;;; CVS Id: $Id: edge-table.lisp,v 1.1 2002/10/25 08:36:42 kevin Exp $
11 ;;;;***************************************************************************
15 (declaim (optimize (safety 1) (debug 3) (speed 3) (compilation-speed 0)))
17 (eval-when (:compile-toplevel :load-toplevel :execute)
18 (defparameter *edge-and-x-lists*
19 '((22 11 12 13 14 15 16 17 18 27)
20 (72 81 82 83 84 85 86 87 88 77)
21 (22 11 21 31 41 51 61 71 81 72)
22 (27 18 28 38 48 58 68 78 88 77))
23 "The four edges (with their X-squares)."))
25 (defparameter *top-edge* (first *edge-and-x-lists*))
27 (defvar *edge-table* nil
28 "Array of values to player-to-move for edge positions.")
30 ;;(declaim (type (simple-array fixnum #.(expt 3 10)) *edge-table*))
32 (defun make-edge-table ()
33 (setq *edge-table* (make-array (expt 3 10) :element-type 'fixnum
34 :adjustable nil :fill-pointer nil))
39 (defun map-edge-n-pieces (fn player board n squares index)
40 "Call fn on all edges with n pieces."
41 ;; Index counts 1 for player; 2 for opponent
42 (declare (fixnum index)
45 (type (simple-array fixnum (100)) board)
48 ((< (length squares) n) nil)
49 ((null squares) (funcall fn board index))
50 (t (let ((index3 (* 3 index))
52 (declare (fixnum index3 sq))
53 (map-edge-n-pieces fn player board n (rest squares) index3)
54 (when (and (> n 0) (eql (bref board sq) empty))
55 (setf (bref board sq) player)
56 (map-edge-n-pieces fn player board (- n 1) (rest squares)
58 (setf (bref board sq) (opponent player))
59 (map-edge-n-pieces fn player board (- n 1) (rest squares)
61 (setf (bref board sq) empty))))))
65 (defun possible-edge-moves-value (player board index)
66 "Consider all possible edge moves.
67 Combine their values into a single number."
68 (declare (type board board)
73 (list 1.0 (aref *edge-table* index)) ;; no move
74 (loop for sq in *top-edge* ;; possible moves
75 when (= (bref board sq) empty)
76 collect (possible-edge-move player board sq)))
80 (defun edge-index (player board squares)
81 "The index counts 1 for player; 2 for opponent,
82 on each square---summed as a base 3 number."
83 (declare (type board board)
86 (optimize (speed 3) (safety 1)))
88 (declare (fixnum index))
90 (declare (type square sq))
94 (the fixnum (* index 3))
95 (the fixnum (cond ((= (bref board sq) empty) 0)
96 ((= (bref board sq) player) 1)
100 (defun possible-edge-move (player board sq)
101 "Return a (prob val) pair for a possible edge move."
102 (declare (type board board)
105 (let ((new-board (replace-board (svref *ply-boards* player) board)))
106 (make-move sq player new-board)
107 (list (edge-move-probability player board sq)
108 (- (aref *edge-table*
109 (edge-index (opponent player)
110 new-board *top-edge*))))))
112 (defun combine-edge-moves (possibilities player)
113 "Combine the best moves."
116 (fn (if (= player black) #'> #'<)))
117 (declare (short-float prob val))
118 (loop for pair in (sort possibilities fn :key #'second)
120 do (incf val (* prob (first pair) (second pair)))
121 (decf prob (* prob (first pair))))
125 (eval-when (:compile-toplevel :load-toplevel :execute)
126 (let ((corner/xsqs '((11 . 22) (18 . 27) (81. 72) (88 . 77))))
127 (defun corner-p (sq) (assoc sq corner/xsqs))
128 (defun x-square-p (sq) (rassoc sq corner/xsqs))
129 (defun x-square-for (corner) (cdr (assoc corner corner/xsqs)))
130 (defun corner-for (xsq) (car (rassoc xsq corner/xsqs)))))
132 (defun edge-move-probability (player board square)
133 "What's the probability that player can move to this square?"
134 (declare (type board board)
136 (type square square))
138 ((x-square-p square) .5) ;; X-squares
139 ((legal-p square player board) 1.0) ;; immediate capture
140 ((corner-p square) ;; move to corner depends on X-square
141 (let ((x-sq (x-square-for square)))
142 (declare (type square x-sq))
144 ((= (bref board x-sq) empty) .1)
145 ((= (bref board x-sq) player) 0.001)
151 (count-edge-neighbors player board square)
152 (count-edge-neighbors (opponent player) board square))
153 (if (legal-p square (opponent player) board) 2 1)))))
155 (defun count-edge-neighbors (player board square)
156 "Count the neighbors of this square occupied by player."
157 (declare (type board board)
159 (type square square))
160 (count-if #'(lambda (inc)
161 (declare (type square inc))
162 (= (bref board (+ square inc)) player))
165 (defparameter *static-edge-table*
178 (declaim (type (simple-array t (* *)) *static-edge-table*))
180 (defun static-edge-stability (player board)
181 "Compute this edge's static stability"
182 (declare (type board board)
183 (type player player))
184 (loop for sq in *top-edge*
188 ((= (bref board sq) empty) 0)
189 ((= (bref board sq) player)
190 (aref *static-edge-table* i
191 (piece-stability board sq)))
192 (t (- (aref *static-edge-table* i
193 (piece-stability board sq))))))))
195 (eval-when (:compile-toplevel :load-toplevel :execute)
196 (let ((stable 0) (semi-stable 1) (unstable 2))
197 (declaim (type fixnum stable semi-stable unstable))
199 (defun piece-stability (board sq)
200 (declare (type board board)
203 ((corner-p sq) stable)
205 (if (eql (bref board (corner-for sq)) empty)
206 unstable semi-stable))
207 (t (let* ((player (bref board sq))
208 (opp (opponent player))
209 (p1 (find player board :test-not #'eql
211 (p2 (find player board :test-not #'eql
214 (declare (fixnum player opp))
216 ;; unstable pieces can be captured immediately
217 ;; by playing in the empty square
218 ((or (and (eql p1 empty) (eql p2 opp))
219 (and (eql p2 empty) (eql p1 opp)))
221 ;; Semi-stable pieces might be captured
222 ((and (eql p1 opp) (eql p2 opp)
223 (find empty board :start 11 :end 19))
225 ((and (eql p1 empty) (eql p2 empty))
227 ;; Stable pieces can never be captured
231 (defun init-edge-table ()
232 "Initialize *edge-table*, starting from the empty board."
233 ;; Initialize the static values
234 (loop for n-pieces from 0 to 10 do
236 #'(lambda (board index)
237 (declare (type board board)
239 (setf (aref *edge-table* index)
240 (the fixnum (static-edge-stability black board))))
241 black (initial-board) n-pieces *top-edge* 0))
242 ;; Now iterate five times trying to improve:
245 ;; Do the indexes with most pieces first
246 (loop for n-pieces from 9 downto 1 do
248 #'(lambda (board index)
249 (declare (type board board)
251 (setf (aref *edge-table* index)
252 (the fixnum (possible-edge-moves-value black board index))))
253 black (initial-board) n-pieces *top-edge* 0))))