OpenBSD-4.6/games/backgammon/backgammon/pubeval.c
/* $OpenBSD: pubeval.c,v 1.1 2002/07/30 18:11:52 pjanzen Exp $ */
/* Public domain, Gerry Tesauro. */
#ifndef lint
static const char rcsid[] = "$OpenBSD: pubeval.c,v 1.1 2002/07/30 18:11:52 pjanzen Exp $";
#endif
/* Backgammon move-selection evaluation function for benchmark comparisons.
* Computes a linear evaluation function: Score = W * X, where X is an
* input vector encoding the board state (using a raw encoding of the number
* of men at each location), and W is a weight vector. Separate weight
* vectors are used for racing positions and contact positions. Makes lots
* of obvious mistakes, but provides a decent level of play for benchmarking
* purposes.
*/
/* Provided as a public service to the backgammon programming community by
* Gerry Tesauro, IBM Research. (e-mail: tesauro@watson.ibm.com)
*/
/* The following inputs are needed for this routine:
*
* race is an integer variable which should be set based on the INITIAL
* position BEFORE the move. Set race=1 if the position is a race (i.e. no
* contact) and 0 if the position is a contact position.
*
* pos[] is an integer array of dimension 28 which should represent a legal
* final board state after the move. Elements 1-24 correspond to board
* locations 1-24 from computer's point of view, i.e. computer's men move in
* the negative direction from 24 to 1, and opponent's men move in the
* positive direction from 1 to 24. Computer's men are represented by
* positive integers, and opponent's men are represented by negative
* integers. Element 25 represents computer's men on the bar (positive
* integer), and element 0 represents opponent's men on the bar (negative
* integer). Element 26 represents computer's men off the board (positive
* integer), and element 27 represents opponent's men off the board
* (negative integer).
*/
#include "back.h"
#include "backlocal.h"
static float x[122];
static int pos[28];
static const float wc[122] = {
0.25696, -0.66937, -1.66135, -2.02487, -2.53398, -0.16092, -1.11725, -1.06654,
-0.92830, -1.99558, -1.10388, -0.80802, 0.09856, -0.62086, -1.27999, -0.59220,
-0.73667, 0.89032, -0.38933, -1.59847, -1.50197, -0.60966, 1.56166, -0.47389,
-1.80390, -0.83425, -0.97741, -1.41371, 0.24500, 0.10970, -1.36476, -1.05572,
1.15420, 0.11069, -0.38319, -0.74816, -0.59244, 0.81116, -0.39511, 0.11424,
-0.73169, -0.56074, 1.09792, 0.15977, 0.13786, -1.18435, -0.43363, 1.06169,
-0.21329, 0.04798, -0.94373, -0.22982, 1.22737, -0.13099, -0.06295, -0.75882,
-0.13658, 1.78389, 0.30416, 0.36797, -0.69851, 0.13003, 1.23070, 0.40868,
-0.21081, -0.64073, 0.31061, 1.59554, 0.65718, 0.25429, -0.80789, 0.08240,
1.78964, 0.54304, 0.41174, -1.06161, 0.07851, 2.01451, 0.49786, 0.91936,
-0.90750, 0.05941, 1.83120, 0.58722, 1.28777, -0.83711, -0.33248, 2.64983,
0.52698, 0.82132, -0.58897, -1.18223, 3.35809, 0.62017, 0.57353, -0.07276,
-0.36214, 4.37655, 0.45481, 0.21746, 0.10504, -0.61977, 3.54001, 0.04612,
-0.18108, 0.63211, -0.87046, 2.47673, -0.48016, -1.27157, 0.86505, -1.11342,
1.24612, -0.82385, -2.77082, 1.23606, -1.59529, 0.10438, -1.30206, -4.11520,
5.62596, -2.75800
};
static const float wr[122] = {
0.00000, -0.17160, 0.27010, 0.29906, -0.08471, 0.00000, -1.40375, -1.05121,
0.07217, -0.01351, 0.00000, -1.29506, -2.16183, 0.13246, -1.03508, 0.00000,
-2.29847, -2.34631, 0.17253, 0.08302, 0.00000, -1.27266, -2.87401, -0.07456,
-0.34240, 0.00000, -1.34640, -2.46556, -0.13022, -0.01591, 0.00000, 0.27448,
0.60015, 0.48302, 0.25236, 0.00000, 0.39521, 0.68178, 0.05281, 0.09266,
0.00000, 0.24855, -0.06844, -0.37646, 0.05685, 0.00000, 0.17405, 0.00430,
0.74427, 0.00576, 0.00000, 0.12392, 0.31202, -0.91035, -0.16270, 0.00000,
0.01418, -0.10839, -0.02781, -0.88035, 0.00000, 1.07274, 2.00366, 1.16242,
0.22520, 0.00000, 0.85631, 1.06349, 1.49549, 0.18966, 0.00000, 0.37183,
-0.50352, -0.14818, 0.12039, 0.00000, 0.13681, 0.13978, 1.11245, -0.12707,
0.00000, -0.22082, 0.20178, -0.06285, -0.52728, 0.00000, -0.13597, -0.19412,
-0.09308, -1.26062, 0.00000, 3.05454, 5.16874, 1.50680, 5.35000, 0.00000,
2.19605, 3.85390, 0.88296, 2.30052, 0.00000, 0.92321, 1.08744, -0.11696,
-0.78560, 0.00000, -0.09795, -0.83050, -1.09167, -4.94251, 0.00000, -1.00316,
-3.66465, -2.56906, -9.67677, 0.00000, -2.77982, -7.26713, -3.40177,-12.32252,
0.00000, 3.42040
};
float
pubeval(int race)
{
int i;
float score;
if (pos[26] == 15)
return (99999999.);
/* all men off, best possible move */
setx(); /* sets input array x[] */
score = 0.0;
if (race) { /* use race weights */
for (i = 0; i < 122; ++i)
score += wr[i] * x[i];
} else { /* use contact weights */
for (i = 0; i < 122; ++i)
score += wc[i] * x[i];
}
return (score);
}
/* sets input vector x[] given board position pos[] */
void
setx()
{
int i, j, jm1, n;
/* initialize */
for (j = 0; j < 122; ++j)
x[j] = 0.0;
if (cturn > 0) { /* we are red, going from 1->24 */
for (i = 0; i < 26; i++)
pos[25 - i] = board[i];
} else { /* we are white, going from 24 -> 1 */
for (i = 0; i < 26; i++)
pos[i] = -board[i];
}
pos[26] = *offptr;
pos[27] = -(*offopp);
/* first encode board locations 24-1 */
for (j = 1; j <= 24; ++j) {
jm1 = j - 1;
n = pos[25 - j];
if (n != 0) {
if (n == -1)
x[5 * jm1 + 0] = 1.0;
else if (n == 1)
x[5 * jm1 + 1] = 1.0;
else if (n == 3)
x[5 * jm1 + 3] = 1.0;
if (n >= 4)
x[5 * jm1 + 4] = (float) (n - 3) / 2.0;
if (n >= 2)
x[5 * jm1 + 2] = 1.0;
}
}
/* encode opponent barmen */
x[120] = -(float) (pos[0]) / 2.0;
/* encode computer's menoff */
x[121] = (float) (pos[26]) / 15.0;
}