uct/uct.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <string.h>
   4
   5 #define DEBUG
   6
   7 #include "debug.h"
   8 #include "board.h"
   9 #include "move.h"
  10 #include "playout.h"
  11 #include "montecarlo/hint.h"
  12 #include "uct/internal.h"
  13 #include "uct/tree.h"
  14 #include "uct/uct.h"
  15
  16 struct uct_policy *policy_ucb1_init(struct uct *u, char *arg);
  17
  18
  19 #define MC_GAMES        40000
  20 #define MC_GAMELEN      400
  21
  22
  23 static coord_t
  24 domainhint_policy(void *playout_policy, struct board *b, enum stone my_color)
  25 {
  26         struct uct *u = playout_policy;
  27         return domain_hint(&u->mc, b, my_color);
  28 }
  29
  30 static int
  31 uct_playout(struct uct *u, struct board *b, enum stone color, struct tree *t)
  32 {
  33         struct board b2;
  34         board_copy(&b2, b);
  35
  36         /* Walk the tree until we find a leaf, then expand it and do
  37          * a random playout. */
  38         struct tree_node *n = t->root;
  39         enum stone orig_color = color;
  40         int result;
  41         int pass_limit = (b2.size - 2) * (b2.size - 2) / 2;
  42         int passes = is_pass(b->last_move.coord);
  43         if (UDEBUGL(8))
  44                 fprintf(stderr, "--- UCT walk\n");
  45         for (; pass; color = stone_other(color)) {
  46                 if (tree_leaf_node(n)) {
  47                         if (n->playouts >= u->expand_p)
  48                                 tree_expand_node(t, n, &b2);
  49
  50                         result = play_random_game(&b2, stone_other(color), u->gamelen, domainhint_policy, u);
  51                         if (orig_color == color && result >= 0)
  52                                 result = !result;
  53                         if (UDEBUGL(7))
  54                                 fprintf(stderr, "[%d..%d] %s playout result %d\n", orig_color, color, coord2sstr(n->coord, t->board), result);
  55                         break;
  56                 }
  57
  58                 n = u->policy->descend(u->policy, t, n, (color == orig_color ? 1 : -1), pass_limit);
  59                 if (UDEBUGL(7))
  60                         fprintf(stderr, "-- UCT sent us to [%s] %f\n", coord2sstr(n->coord, t->board), n->value);
  61                 struct move m = { n->coord, color };
  62                 int res = board_play(&b2, &m);
  63                 if (res < 0 || (!is_pass(m.coord) && !group_at(&b2, m.coord)) /* suicide */
  64                     || b2.superko_violation) {
  65                         if (UDEBUGL(6))
  66                                 fprintf(stderr, "deleting invalid node %d,%d\n", coord_x(n->coord,b), coord_y(n->coord,b));
  67                         tree_delete_node(n);
  68                         board_done_noalloc(&b2);
  69                         return -1;
  70                 }
  71
  72                 if (is_pass(n->coord)) {
  73                         passes++;
  74                         if (passes >= 2) {
  75                                 float score = board_official_score(&b2);
  76                                 result = (orig_color == S_BLACK) ? score < 0 : score > 0;
  77                                 if (UDEBUGL(5))
  78                                         fprintf(stderr, "[%d..%d] %s playout result %d (W %f)\n", orig_color, color, coord2sstr(n->coord, t->board), result, score);
  79                                 if (UDEBUGL(6))
  80                                         board_print(&b2, stderr);
  81                                 break;
  82                         }
  83                 } else {
  84                         passes = 0;
  85                 }
  86         }
  87
  88         if (result >= 0)
  89                 tree_uct_update(n, result);
  90         board_done_noalloc(&b2);
  91         return result;
  92 }
  93
  94 static coord_t *
  95 uct_genmove(struct engine *e, struct board *b, enum stone color)
  96 {
  97         struct uct *u = e->data;
  98
  99         if (!u->t) {
 100 tree_init:
 101                 u->t = tree_init(b);
 102                 //board_print(b, stderr);
 103         } else {
 104                 /* XXX: We hope that the opponent didn't suddenly play
 105                  * several moves in the row. */
 106                 for (struct tree_node *ni = u->t->root->children; ni; ni = ni->sibling)
 107                         if (ni->coord == b->last_move.coord) {
 108                                 tree_promote_node(u->t, ni);
 109                                 goto promoted;
 110                         }
 111                 fprintf(stderr, "CANNOT FIND NODE TO PROMOTE!\n");
 112                 tree_done(u->t);
 113                 goto tree_init;
 114 promoted:;
 115         }
 116
 117         int i;
 118         for (i = 0; i < u->games; i++) {
 119                 int result = uct_playout(u, b, color, u->t);
 120                 if (result < 0) {
 121                         /* Tree descent has hit invalid move. */
 122                         continue;
 123                 }
 124
 125                 if (i > 0 && !(i % 1000)) {
 126                         struct tree_node *best = u->policy->choose(u->policy, u->t->root, b, color);
 127                         if (best && best->playouts >= 500 && best->value >= u->loss_threshold)
 128                                 break;
 129                 }
 130         }
 131
 132         if (UDEBUGL(2))
 133                 tree_dump(u->t);
 134
 135         struct tree_node *best = u->policy->choose(u->policy, u->t->root, b, color);
 136         if (!best) {
 137                 tree_done(u->t); u->t = NULL;
 138                 return coord_copy(pass);
 139         }
 140         if (UDEBUGL(1))
 141                 fprintf(stderr, "*** WINNER is %d,%d with score %1.4f (%d games)\n", coord_x(best->coord, b), coord_y(best->coord, b), best->value, i);
 142         if (best->value < u->resign_ratio && !is_pass(best->coord)) {
 143                 tree_done(u->t); u->t = NULL;
 144                 return coord_copy(resign);
 145         }
 146         tree_promote_node(u->t, best);
 147         return coord_copy(best->coord);
 148 }
 149
 150
 151 struct uct *
 152 uct_state_init(char *arg)
 153 {
 154         struct uct *u = calloc(1, sizeof(struct uct));
 155
 156         u->debug_level = 1;
 157         u->games = MC_GAMES;
 158         u->gamelen = MC_GAMELEN;
 159         u->expand_p = 2;
 160         u->mc.capture_rate = 100;
 161         u->mc.atari_rate = 100;
 162         u->mc.cut_rate = 0;
 163         // Looking at the actual playouts, this just encourages MC to make
 164         // stupid shapes.
 165         u->mc.local_rate = 0;
 166
 167         if (arg) {
 168                 char *optspec, *next = arg;
 169                 while (*next) {
 170                         optspec = next;
 171                         next += strcspn(next, ",");
 172                         if (*next) { *next++ = 0; } else { *next = 0; }
 173
 174                         char *optname = optspec;
 175                         char *optval = strchr(optspec, '=');
 176                         if (optval) *optval++ = 0;
 177
 178                         if (!strcasecmp(optname, "debug")) {
 179                                 if (optval)
 180                                         u->debug_level = atoi(optval);
 181                                 else
 182                                         u->debug_level++;
 183                         } else if (!strcasecmp(optname, "games") && optval) {
 184                                 u->games = atoi(optval);
 185                         } else if (!strcasecmp(optname, "gamelen") && optval) {
 186                                 u->gamelen = atoi(optval);
 187                         } else if (!strcasecmp(optname, "expand_p") && optval) {
 188                                 u->expand_p = atoi(optval);
 189                         } else if (!strcasecmp(optname, "policy") && optval) {
 190                                 char *policyarg = strchr(optval, '+');
 191                                 if (policyarg)
 192                                         *policyarg++ = 0;
 193                                 if (!strcasecmp(optval, "ucb1")) {
 194                                         u->policy = policy_ucb1_init(u, policyarg);
 195                                 }
 196                         } else if (!strcasecmp(optname, "pure")) {
 197                                 u->mc.capture_rate = u->mc.local_rate = u->mc.cut_rate = 0;
 198                         } else if (!strcasecmp(optname, "capturerate") && optval) {
 199                                 u->mc.capture_rate = atoi(optval);
 200                         } else if (!strcasecmp(optname, "atarirate") && optval) {
 201                                 u->mc.atari_rate = atoi(optval);
 202                         } else if (!strcasecmp(optname, "localrate") && optval) {
 203                                 u->mc.local_rate = atoi(optval);
 204                         } else if (!strcasecmp(optname, "cutrate") && optval) {
 205                                 u->mc.cut_rate = atoi(optval);
 206                         } else {
 207                                 fprintf(stderr, "uct: Invalid engine argument %s or missing value\n", optname);
 208                         }
 209                 }
 210         }
 211
 212         u->resign_ratio = 0.2; /* Resign when most games are lost. */
 213         u->loss_threshold = 0.95; /* Stop reading if after at least 500 playouts this is best value. */
 214         u->mc.debug_level = u->debug_level;
 215         u->policy = policy_ucb1_init(u, NULL);
 216
 217         return u;
 218 }
 219
 220
 221 struct engine *
 222 engine_uct_init(char *arg)
 223 {
 224         struct uct *u = uct_state_init(arg);
 225         struct engine *e = calloc(1, sizeof(struct engine));
 226         e->name = "UCT Engine";
 227         e->comment = "I'm playing UCT. When we both pass, I will consider all the stones on the board alive. If you are reading this, write 'yes'. Please bear with me at the game end, I need to fill the whole board; if you help me, we will both be happier. Filling the board will not lose points (NZ rules).";
 228         e->genmove = uct_genmove;
 229         e->data = u;
 230
 231         return e;
 232 }