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 struct uct_policy *policy_ucb1tuned_init(struct uct *u, char *arg);
  18
  19
  20 #define MC_GAMES        40000
  21 #define MC_GAMELEN      400
  22
  23
  24 static coord_t
  25 domainhint_policy(void *playout_policy, struct board *b, enum stone my_color)
  26 {
  27         struct uct *u = playout_policy;
  28         return domain_hint(&u->mc, b, my_color);
  29 }
  30
  31 static int
  32 uct_playout(struct uct *u, struct board *b, enum stone color, struct tree *t)
  33 {
  34         struct board b2;
  35         board_copy(&b2, b);
  36
  37         /* Walk the tree until we find a leaf, then expand it and do
  38          * a random playout. */
  39         struct tree_node *n = t->root;
  40         enum stone orig_color = color;
  41         int result;
  42         int pass_limit = (b2.size - 2) * (b2.size - 2) / 2;
  43         int passes = is_pass(b->last_move.coord);
  44         if (UDEBUGL(8))
  45                 fprintf(stderr, "--- UCT walk\n");
  46         for (; pass; color = stone_other(color)) {
  47                 if (tree_leaf_node(n)) {
  48                         if (n->playouts >= u->expand_p)
  49                                 tree_expand_node(t, n, &b2);
  50
  51                         result = play_random_game(&b2, stone_other(color), u->gamelen, domainhint_policy, u);
  52                         if (orig_color == color && result >= 0)
  53                                 result = !result;
  54                         if (UDEBUGL(7))
  55                                 fprintf(stderr, "[%d..%d] %s playout result %d\n", orig_color, color, coord2sstr(n->coord, t->board), result);
  56                         break;
  57                 }
  58
  59                 n = u->policy->descend(u->policy, t, n, (color == orig_color ? 1 : -1), pass_limit);
  60                 if (UDEBUGL(7))
  61                         fprintf(stderr, "-- UCT sent us to [%s] %f\n", coord2sstr(n->coord, t->board), n->value);
  62                 struct move m = { n->coord, color };
  63                 int res = board_play(&b2, &m);
  64                 if (res < 0 || (!is_pass(m.coord) && !group_at(&b2, m.coord)) /* suicide */
  65                     || b2.superko_violation) {
  66                         if (UDEBUGL(6))
  67                                 fprintf(stderr, "deleting invalid node %d,%d\n", coord_x(n->coord,b), coord_y(n->coord,b));
  68                         tree_delete_node(n);
  69                         board_done_noalloc(&b2);
  70                         return -1;
  71                 }
  72
  73                 if (is_pass(n->coord)) {
  74                         passes++;
  75                         if (passes >= 2) {
  76                                 float score = board_official_score(&b2);
  77                                 result = (orig_color == S_BLACK) ? score < 0 : score > 0;
  78                                 if (UDEBUGL(5))
  79                                         fprintf(stderr, "[%d..%d] %s playout result %d (W %f)\n", orig_color, color, coord2sstr(n->coord, t->board), result, score);
  80                                 if (UDEBUGL(6))
  81                                         board_print(&b2, stderr);
  82                                 break;
  83                         }
  84                 } else {
  85                         passes = 0;
  86                 }
  87         }
  88
  89         if (result >= 0)
  90                 tree_uct_update(n, result);
  91         board_done_noalloc(&b2);
  92         return result;
  93 }
  94
  95 static coord_t *
  96 uct_genmove(struct engine *e, struct board *b, enum stone color)
  97 {
  98         struct uct *u = e->data;
  99
 100         if (!u->t) {
 101 tree_init:
 102                 u->t = tree_init(b);
 103                 //board_print(b, stderr);
 104         } else {
 105                 /* XXX: We hope that the opponent didn't suddenly play
 106                  * several moves in the row. */
 107                 for (struct tree_node *ni = u->t->root->children; ni; ni = ni->sibling)
 108                         if (ni->coord == b->last_move.coord) {
 109                                 tree_promote_node(u->t, ni);
 110                                 goto promoted;
 111                         }
 112                 fprintf(stderr, "CANNOT FIND NODE TO PROMOTE!\n");
 113                 tree_done(u->t);
 114                 goto tree_init;
 115 promoted:;
 116         }
 117
 118         int i;
 119         for (i = 0; i < u->games; i++) {
 120                 int result = uct_playout(u, b, color, u->t);
 121                 if (result < 0) {
 122                         /* Tree descent has hit invalid move. */
 123                         continue;
 124                 }
 125
 126                 if (i > 0 && !(i % 1000)) {
 127                         struct tree_node *best = u->policy->choose(u->policy, u->t->root, b, color);
 128                         if (best && best->playouts >= 500 && best->value >= u->loss_threshold)
 129                                 break;
 130                 }
 131         }
 132
 133         if (UDEBUGL(2))
 134                 tree_dump(u->t);
 135
 136         struct tree_node *best = u->policy->choose(u->policy, u->t->root, b, color);
 137         if (!best) {
 138                 tree_done(u->t); u->t = NULL;
 139                 return coord_copy(pass);
 140         }
 141         if (UDEBUGL(1))
 142                 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);
 143         if (best->value < u->resign_ratio && !is_pass(best->coord)) {
 144                 tree_done(u->t); u->t = NULL;
 145                 return coord_copy(resign);
 146         }
 147         tree_promote_node(u->t, best);
 148         return coord_copy(best->coord);
 149 }
 150
 151
 152 struct uct *
 153 uct_state_init(char *arg)
 154 {
 155         struct uct *u = calloc(1, sizeof(struct uct));
 156
 157         u->debug_level = 1;
 158         u->games = MC_GAMES;
 159         u->gamelen = MC_GAMELEN;
 160         u->expand_p = 2;
 161         u->mc.capture_rate = 100;
 162         u->mc.atari_rate = 100;
 163         u->mc.cut_rate = 0;
 164         // Looking at the actual playouts, this just encourages MC to make
 165         // stupid shapes.
 166         u->mc.local_rate = 0;
 167
 168         if (arg) {
 169                 char *optspec, *next = arg;
 170                 while (*next) {
 171                         optspec = next;
 172                         next += strcspn(next, ",");
 173                         if (*next) { *next++ = 0; } else { *next = 0; }
 174
 175                         char *optname = optspec;
 176                         char *optval = strchr(optspec, '=');
 177                         if (optval) *optval++ = 0;
 178
 179                         if (!strcasecmp(optname, "debug")) {
 180                                 if (optval)
 181                                         u->debug_level = atoi(optval);
 182                                 else
 183                                         u->debug_level++;
 184                         } else if (!strcasecmp(optname, "games") && optval) {
 185                                 u->games = atoi(optval);
 186                         } else if (!strcasecmp(optname, "gamelen") && optval) {
 187                                 u->gamelen = atoi(optval);
 188                         } else if (!strcasecmp(optname, "expand_p") && optval) {
 189                                 u->expand_p = atoi(optval);
 190                         } else if (!strcasecmp(optname, "policy") && optval) {
 191                                 char *policyarg = strchr(optval, '+');
 192                                 if (policyarg)
 193                                         *policyarg++ = 0;
 194                                 if (!strcasecmp(optval, "ucb1")) {
 195                                         u->policy = policy_ucb1_init(u, policyarg);
 196                                 } else if (!strcasecmp(optval, "ucb1tuned")) {
 197                                         u->policy = policy_ucb1tuned_init(u, policyarg);
 198                                 }
 199                         } else if (!strcasecmp(optname, "pure")) {
 200                                 u->mc.capture_rate = u->mc.local_rate = u->mc.cut_rate = 0;
 201                         } else if (!strcasecmp(optname, "capturerate") && optval) {
 202                                 u->mc.capture_rate = atoi(optval);
 203                         } else if (!strcasecmp(optname, "atarirate") && optval) {
 204                                 u->mc.atari_rate = atoi(optval);
 205                         } else if (!strcasecmp(optname, "localrate") && optval) {
 206                                 u->mc.local_rate = atoi(optval);
 207                         } else if (!strcasecmp(optname, "cutrate") && optval) {
 208                                 u->mc.cut_rate = atoi(optval);
 209                         } else {
 210                                 fprintf(stderr, "uct: Invalid engine argument %s or missing value\n", optname);
 211                         }
 212                 }
 213         }
 214
 215         u->resign_ratio = 0.2; /* Resign when most games are lost. */
 216         u->loss_threshold = 0.95; /* Stop reading if after at least 500 playouts this is best value. */
 217         u->mc.debug_level = u->debug_level;
 218         u->policy = policy_ucb1_init(u, NULL);
 219
 220         return u;
 221 }
 222
 223
 224 struct engine *
 225 engine_uct_init(char *arg)
 226 {
 227         struct uct *u = uct_state_init(arg);
 228         struct engine *e = calloc(1, sizeof(struct engine));
 229         e->name = "UCT Engine";
 230         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).";
 231         e->genmove = uct_genmove;
 232         e->data = u;
 233
 234         return e;
 235 }