uct/uct.c

   1 #include <assert.h>
   2 #include <pthread.h>
   3 #include <signal.h>
   4 #include <stdio.h>
   5 #include <stdlib.h>
   6 #include <string.h>
   7
   8 #define DEBUG
   9
  10 #include "debug.h"
  11 #include "board.h"
  12 #include "move.h"
  13 #include "playout.h"
  14 #include "playout/moggy.h"
  15 #include "playout/light.h"
  16 #include "random.h"
  17 #include "uct/internal.h"
  18 #include "uct/prior.h"
  19 #include "uct/tree.h"
  20 #include "uct/uct.h"
  21
  22 struct uct_policy *policy_ucb1_init(struct uct *u, char *arg);
  23 struct uct_policy *policy_ucb1tuned_init(struct uct *u, char *arg);
  24 struct uct_policy *policy_ucb1amaf_init(struct uct *u, char *arg);
  25
  26
  27 #define MC_GAMES        80000
  28 #define MC_GAMELEN      MAX_GAMELEN
  29
  30
  31 static bool
  32 can_pass(struct board *b, enum stone color)
  33 {
  34         float score = board_official_score(b);
  35         if (color == S_BLACK)
  36                 score = -score;
  37         //fprintf(stderr, "%d score %f\n", color, score);
  38         return (score > 0);
  39 }
  40
  41 static void
  42 progress_status(struct uct *u, struct tree *t, enum stone color, int playouts)
  43 {
  44         if (!UDEBUGL(0))
  45                 return;
  46
  47         /* Best move */
  48         struct tree_node *best = u->policy->choose(u->policy, t->root, t->board, color);
  49         if (!best) {
  50                 fprintf(stderr, "... No moves left\n");
  51                 return;
  52         }
  53         fprintf(stderr, "[%d] ", playouts);
  54         fprintf(stderr, "best %f ", tree_node_get_value(t, best, u, 1));
  55
  56         /* Max depth */
  57         fprintf(stderr, "deepest % 2d ", t->max_depth - t->root->depth);
  58
  59         /* Best sequence */
  60         fprintf(stderr, "| seq ");
  61         for (int depth = 0; depth < 6; depth++) {
  62                 if (best && best->u.playouts >= 25) {
  63                         fprintf(stderr, "%3s ", coord2sstr(best->coord, t->board));
  64                         best = u->policy->choose(u->policy, best, t->board, color);
  65                 } else {
  66                         fprintf(stderr, "    ");
  67                 }
  68         }
  69
  70         /* Best candidates */
  71         fprintf(stderr, "| can ");
  72         int cans = 4;
  73         struct tree_node *can[cans];
  74         memset(can, 0, sizeof(can));
  75         best = t->root->children;
  76         while (best) {
  77                 int c = 0;
  78                 while ((!can[c] || best->u.playouts > can[c]->u.playouts) && ++c < cans);
  79                 for (int d = 0; d < c; d++) can[d] = can[d + 1];
  80                 if (c > 0) can[c - 1] = best;
  81                 best = best->sibling;
  82         }
  83         while (--cans >= 0) {
  84                 if (can[cans]) {
  85                         fprintf(stderr, "%3s(%.3f) ",
  86                                 coord2sstr(can[cans]->coord, t->board),
  87                                 tree_node_get_value(t, can[cans], u, 1));
  88                 } else {
  89                         fprintf(stderr, "           ");
  90                 }
  91         }
  92
  93         fprintf(stderr, "\n");
  94 }
  95
  96
  97 static int
  98 uct_leaf_node(struct uct *u, struct board *b, enum stone player_color,
  99               struct playout_amafmap *amaf,
 100               struct tree *t, struct tree_node *n, enum stone node_color,
 101               char *spaces)
 102 {
 103         enum stone next_color = stone_other(node_color);
 104         int parity = (next_color == player_color ? 1 : -1);
 105         if (n->u.playouts >= u->expand_p) {
 106                 // fprintf(stderr, "expanding %s (%p ^-%p)\n", coord2sstr(n->coord, b), n, n->parent);
 107                 tree_expand_node(t, n, b, next_color, u->radar_d, u, parity);
 108         }
 109         if (UDEBUGL(7))
 110                 fprintf(stderr, "%s*-- UCT playout #%d start [%s] %f\n",
 111                         spaces, n->u.playouts, coord2sstr(n->coord, t->board),
 112                         tree_node_get_value(t, n, u, parity));
 113
 114         int result = play_random_game(b, next_color, u->gamelen, u->playout_amaf ? amaf : NULL, u->playout);
 115         if (next_color == S_WHITE && result >= 0) {
 116                 /* We need the result from black's perspective. */
 117                 result = !result;
 118         }
 119         if (UDEBUGL(7))
 120                 fprintf(stderr, "%s -- [%d..%d] %s random playout result %d\n",
 121                         spaces, player_color, next_color, coord2sstr(n->coord, t->board), result);
 122
 123         return result;
 124 }
 125
 126 static int
 127 uct_playout(struct uct *u, struct board *b, enum stone player_color, struct tree *t)
 128 {
 129         struct board b2;
 130         board_copy(&b2, b);
 131
 132         struct playout_amafmap *amaf = NULL;
 133         if (u->policy->wants_amaf) {
 134                 amaf = calloc(1, sizeof(*amaf));
 135                 amaf->map = calloc(board_size2(&b2) + 1, sizeof(*amaf->map));
 136                 amaf->map++; // -1 is pass
 137         }
 138
 139         /* Walk the tree until we find a leaf, then expand it and do
 140          * a random playout. */
 141         struct tree_node *n = t->root;
 142         enum stone node_color = stone_other(player_color);
 143         assert(node_color == t->root_color);
 144
 145         int result;
 146         int pass_limit = (board_size(&b2) - 2) * (board_size(&b2) - 2) / 2;
 147         int passes = is_pass(b->last_move.coord);
 148
 149         /* debug */
 150         int depth = 0;
 151         static char spaces[] = "\0                                                      ";
 152         /* /debug */
 153         if (UDEBUGL(8))
 154                 fprintf(stderr, "--- UCT walk with color %d\n", player_color);
 155
 156         while (!tree_leaf_node(n) && passes < 2) {
 157                 spaces[depth++] = ' '; spaces[depth] = 0;
 158
 159                 /* Parity is chosen already according to the child color, since
 160                  * it is applied to children. */
 161                 node_color = stone_other(node_color);
 162                 int parity = (node_color == player_color ? 1 : -1);
 163                 n = u->policy->descend(u->policy, t, n, parity, pass_limit);
 164
 165                 assert(n == t->root || n->parent);
 166                 if (UDEBUGL(7))
 167                         fprintf(stderr, "%s+-- UCT sent us to [%s:%d] %f\n",
 168                                 spaces, coord2sstr(n->coord, t->board), n->coord,
 169                                 tree_node_get_value(t, n, u, parity));
 170
 171                 assert(n->coord >= -1);
 172                 if (amaf && !is_pass(n->coord)) {
 173                         if (amaf->map[n->coord] == S_NONE || amaf->map[n->coord] == node_color) {
 174                                 amaf->map[n->coord] = node_color;
 175                         } else { // XXX: Respect amaf->record_nakade
 176                                 amaf_op(amaf->map[n->coord], +);
 177                         }
 178                         amaf->game[amaf->gamelen].coord = n->coord;
 179                         amaf->game[amaf->gamelen].color = node_color;
 180                         amaf->gamelen++;
 181                         assert(amaf->gamelen < sizeof(amaf->game) / sizeof(amaf->game[0]));
 182                 }
 183
 184                 struct move m = { n->coord, node_color };
 185                 int res = board_play(&b2, &m);
 186
 187                 if (res < 0 || (!is_pass(m.coord) && !group_at(&b2, m.coord)) /* suicide */
 188                     || b2.superko_violation) {
 189                         if (UDEBUGL(3)) {
 190                                 for (struct tree_node *ni = n; ni; ni = ni->parent)
 191                                         fprintf(stderr, "%s<%lld> ", coord2sstr(ni->coord, t->board), ni->hash);
 192                                 fprintf(stderr, "deleting invalid %s node %d,%d res %d group %d spk %d\n",
 193                                         stone2str(node_color), coord_x(n->coord,b), coord_y(n->coord,b),
 194                                         res, group_at(&b2, m.coord), b2.superko_violation);
 195                         }
 196                         tree_delete_node(t, n);
 197                         result = -1;
 198                         goto end;
 199                 }
 200
 201                 if (is_pass(n->coord))
 202                         passes++;
 203                 else
 204                         passes = 0;
 205         }
 206
 207         if (amaf) {
 208                 amaf->game_baselen = amaf->gamelen;
 209                 amaf->record_nakade = u->playout_amaf_nakade;
 210         }
 211
 212         if (passes >= 2) {
 213                 float score = board_official_score(&b2);
 214                 /* Result from black's perspective (no matter who
 215                  * the player; black's perspective is always
 216                  * what the tree stores. */
 217                 result = score < 0;
 218
 219                 if (UDEBUGL(5))
 220                         fprintf(stderr, "[%d..%d] %s p-p scoring playout result %d (W %f)\n",
 221                                 player_color, node_color, coord2sstr(n->coord, t->board), result, score);
 222                 if (UDEBUGL(6))
 223                         board_print(&b2, stderr);
 224
 225         } else { assert(tree_leaf_node(n));
 226                 result = uct_leaf_node(u, &b2, player_color, amaf, t, n, node_color, spaces);
 227         }
 228
 229         if (amaf && u->playout_amaf_cutoff) {
 230                 int cutoff = amaf->game_baselen;
 231                 cutoff += (amaf->gamelen - amaf->game_baselen) * u->playout_amaf_cutoff / 100;
 232                 /* Now, reconstruct the amaf map. */
 233                 memset(amaf->map, 0, board_size2(&b2) * sizeof(*amaf->map));
 234                 for (int i = 0; i < cutoff; i++) {
 235                         coord_t coord = amaf->game[i].coord;
 236                         enum stone color = amaf->game[i].color;
 237                         if (amaf->map[coord] == S_NONE || amaf->map[coord] == color) {
 238                                 amaf->map[coord] = color;
 239                         /* Nakade always recorded for in-tree part */
 240                         } else if (amaf->record_nakade || i <= amaf->game_baselen) {
 241                                 amaf_op(amaf->map[n->coord], +);
 242                         }
 243                 }
 244         }
 245
 246         assert(n == t->root || n->parent);
 247         if (result >= 0)
 248                 u->policy->update(u->policy, t, n, node_color, player_color, amaf, result);
 249
 250 end:
 251         if (amaf) {
 252                 free(amaf->map - 1);
 253                 free(amaf);
 254         }
 255         board_done_noalloc(&b2);
 256         return result;
 257 }
 258
 259 static void
 260 prepare_move(struct engine *e, struct board *b, enum stone color, coord_t promote)
 261 {
 262         struct uct *u = e->data;
 263
 264         if (u->t && (!b->moves || color != stone_other(u->t->root_color))) {
 265                 /* Stale state from last game */
 266                 tree_done(u->t);
 267                 u->t = NULL;
 268         }
 269
 270         if (!u->t) {
 271                 u->t = tree_init(b, color);
 272                 if (u->force_seed)
 273                         fast_srandom(u->force_seed);
 274                 if (UDEBUGL(0))
 275                         fprintf(stderr, "Fresh board with random seed %lu\n", fast_getseed());
 276                 //board_print(b, stderr);
 277                 if (!u->no_book && b->moves < 2)
 278                         tree_load(u->t, b);
 279         }
 280
 281         /* XXX: We hope that the opponent didn't suddenly play
 282          * several moves in the row. */
 283         if (!is_resign(promote) && !tree_promote_at(u->t, b, promote)) {
 284                 if (UDEBUGL(2))
 285                         fprintf(stderr, "<cannot find node to promote>\n");
 286                 /* Reset tree */
 287                 tree_done(u->t);
 288                 u->t = tree_init(b, color);
 289         }
 290 }
 291
 292 /* Set in main thread in case the playouts should stop. */
 293 static volatile sig_atomic_t halt = 0;
 294
 295 static int
 296 uct_playouts(struct uct *u, struct board *b, enum stone color, struct tree *t)
 297 {
 298         int i, games = u->games;
 299         if (t->root->children)
 300                 games -= t->root->u.playouts / 1.5;
 301         /* else this is highly read-out but dead-end branch of opening book;
 302          * we need to start from scratch; XXX: Maybe actually base the readout
 303          * count based on number of playouts of best node? */
 304         for (i = 0; i < games; i++) {
 305                 int result = uct_playout(u, b, color, t);
 306                 if (result < 0) {
 307                         /* Tree descent has hit invalid move. */
 308                         continue;
 309                 }
 310
 311                 if (i > 0 && !(i % 10000)) {
 312                         progress_status(u, t, color, i);
 313                 }
 314
 315                 if (i > 0 && !(i % 500)) {
 316                         struct tree_node *best = u->policy->choose(u->policy, t->root, b, color);
 317                         if (best && ((best->u.playouts >= 5000 && tree_node_get_value(t, best, u, 1) >= u->loss_threshold)
 318                                      || (best->u.playouts >= 500 && tree_node_get_value(t, best, u, 1) >= 0.95)))
 319                                 break;
 320                 }
 321
 322                 if (halt) {
 323                         if (UDEBUGL(2))
 324                                 fprintf(stderr, "<halting early, %d games skipped>\n", games - i);
 325                         break;
 326                 }
 327         }
 328
 329         progress_status(u, t, color, i);
 330         if (UDEBUGL(3))
 331                 tree_dump(t, u->dumpthres);
 332         return i;
 333 }
 334
 335 static pthread_mutex_t finish_mutex = PTHREAD_MUTEX_INITIALIZER;
 336 static pthread_cond_t finish_cond = PTHREAD_COND_INITIALIZER;
 337 static volatile int finish_thread;
 338 static pthread_mutex_t finish_serializer = PTHREAD_MUTEX_INITIALIZER;
 339
 340 struct spawn_ctx {
 341         int tid;
 342         struct uct *u;
 343         struct board *b;
 344         enum stone color;
 345         struct tree *t;
 346         unsigned long seed;
 347         int games;
 348 };
 349
 350 static void *
 351 spawn_helper(void *ctx_)
 352 {
 353         struct spawn_ctx *ctx = ctx_;
 354         /* Setup */
 355         fast_srandom(ctx->seed);
 356         /* Run */
 357         ctx->games = uct_playouts(ctx->u, ctx->b, ctx->color, ctx->t);
 358         /* Finish */
 359         pthread_mutex_lock(&finish_serializer);
 360         pthread_mutex_lock(&finish_mutex);
 361         finish_thread = ctx->tid;
 362         pthread_cond_signal(&finish_cond);
 363         pthread_mutex_unlock(&finish_mutex);
 364         return ctx;
 365 }
 366
 367 static void
 368 uct_notify_play(struct engine *e, struct board *b, struct move *m)
 369 {
 370         prepare_move(e, b, m->color, m->coord);
 371 }
 372
 373 static coord_t *
 374 uct_genmove(struct engine *e, struct board *b, enum stone color)
 375 {
 376         struct uct *u = e->data;
 377
 378         /* Seed the tree. */
 379         prepare_move(e, b, color, resign);
 380
 381         if (b->superko_violation) {
 382                 fprintf(stderr, "!!! WARNING: SUPERKO VIOLATION OCCURED BEFORE THIS MOVE\n");
 383                 fprintf(stderr, "Maybe you play with situational instead of positional superko?\n");
 384                 fprintf(stderr, "I'm going to ignore the violation, but note that I may miss\n");
 385                 fprintf(stderr, "some moves valid under this ruleset because of this.\n");
 386                 b->superko_violation = false;
 387         }
 388
 389         /* If the opponent just passes and we win counting, just
 390          * pass as well. */
 391         if (b->moves > 1 && is_pass(b->last_move.coord) && can_pass(b, color))
 392                 return coord_copy(pass);
 393
 394         int played_games = 0;
 395         if (!u->threads) {
 396                 played_games = uct_playouts(u, b, color, u->t);
 397         } else {
 398                 pthread_t threads[u->threads];
 399                 int joined = 0;
 400                 halt = 0;
 401                 pthread_mutex_lock(&finish_mutex);
 402                 /* Spawn threads... */
 403                 for (int ti = 0; ti < u->threads; ti++) {
 404                         struct spawn_ctx *ctx = malloc(sizeof(*ctx));
 405                         ctx->u = u; ctx->b = b; ctx->color = color;
 406                         ctx->t = tree_copy(u->t); ctx->tid = ti;
 407                         ctx->seed = fast_random(65536) + ti;
 408                         pthread_create(&threads[ti], NULL, spawn_helper, ctx);
 409                         if (UDEBUGL(2))
 410                                 fprintf(stderr, "Spawned thread %d\n", ti);
 411                 }
 412                 /* ...and collect them back: */
 413                 while (joined < u->threads) {
 414                         /* Wait for some thread to finish... */
 415                         pthread_cond_wait(&finish_cond, &finish_mutex);
 416                         /* ...and gather its remnants. */
 417                         struct spawn_ctx *ctx;
 418                         pthread_join(threads[finish_thread], (void **) &ctx);
 419                         played_games += ctx->games;
 420                         joined++;
 421                         tree_merge(u->t, ctx->t, u->amaf_prior);
 422                         tree_done(ctx->t);
 423                         free(ctx);
 424                         if (UDEBUGL(2))
 425                                 fprintf(stderr, "Joined thread %d\n", finish_thread);
 426                         /* Do not get stalled by slow threads. */
 427                         if (joined >= u->threads / 2)
 428                                 halt = 1;
 429                         pthread_mutex_unlock(&finish_serializer);
 430                 }
 431                 pthread_mutex_unlock(&finish_mutex);
 432
 433                 tree_normalize(u->t, u->threads);
 434         }
 435
 436         if (UDEBUGL(2))
 437                 tree_dump(u->t, u->dumpthres);
 438
 439         struct tree_node *best = u->policy->choose(u->policy, u->t->root, b, color);
 440         if (!best) {
 441                 tree_done(u->t); u->t = NULL;
 442                 return coord_copy(pass);
 443         }
 444         if (UDEBUGL(0))
 445                 progress_status(u, u->t, color, played_games);
 446         if (UDEBUGL(1))
 447                 fprintf(stderr, "*** WINNER is %s (%d,%d) with score %1.4f (%d/%d:%d games)\n",
 448                         coord2sstr(best->coord, b), coord_x(best->coord, b), coord_y(best->coord, b),
 449                         tree_node_get_value(u->t, best, u, 1),
 450                         best->u.playouts, u->t->root->u.playouts, played_games);
 451         if (tree_node_get_value(u->t, best, u, 1) < u->resign_ratio && !is_pass(best->coord)) {
 452                 tree_done(u->t); u->t = NULL;
 453                 return coord_copy(resign);
 454         }
 455         tree_promote_node(u->t, best);
 456         return coord_copy(best->coord);
 457 }
 458
 459 bool
 460 uct_genbook(struct engine *e, struct board *b, enum stone color)
 461 {
 462         struct uct *u = e->data;
 463         u->t = tree_init(b, color);
 464         tree_load(u->t, b);
 465
 466         int i;
 467         for (i = 0; i < u->games; i++) {
 468                 int result = uct_playout(u, b, color, u->t);
 469                 if (result < 0) {
 470                         /* Tree descent has hit invalid move. */
 471                         continue;
 472                 }
 473
 474                 if (i > 0 && !(i % 10000)) {
 475                         progress_status(u, u->t, color, i);
 476                 }
 477         }
 478         progress_status(u, u->t, color, i);
 479
 480         tree_save(u->t, b, u->games / 100);
 481
 482         tree_done(u->t);
 483
 484         return true;
 485 }
 486
 487 void
 488 uct_dumpbook(struct engine *e, struct board *b, enum stone color)
 489 {
 490         struct uct *u = e->data;
 491         u->t = tree_init(b, color);
 492         tree_load(u->t, b);
 493         tree_dump(u->t, 0);
 494         tree_done(u->t);
 495 }
 496
 497
 498 struct uct *
 499 uct_state_init(char *arg)
 500 {
 501         struct uct *u = calloc(1, sizeof(struct uct));
 502
 503         u->debug_level = 1;
 504         u->games = MC_GAMES;
 505         u->gamelen = MC_GAMELEN;
 506         u->expand_p = 2;
 507         u->dumpthres = 1000;
 508         u->playout_amaf = true;
 509         u->playout_amaf_nakade = false;
 510         u->amaf_prior = true;
 511
 512         // gp: 14 vs 0: 44% (+-3.5)
 513         u->gp_eqex = 0;
 514         u->even_eqex = u->policy_eqex = u->b19_eqex = u->cfgd_eqex = -1;
 515         u->eqex = 6; /* Even number! */
 516
 517         if (arg) {
 518                 char *optspec, *next = arg;
 519                 while (*next) {
 520                         optspec = next;
 521                         next += strcspn(next, ",");
 522                         if (*next) { *next++ = 0; } else { *next = 0; }
 523
 524                         char *optname = optspec;
 525                         char *optval = strchr(optspec, '=');
 526                         if (optval) *optval++ = 0;
 527
 528                         if (!strcasecmp(optname, "debug")) {
 529                                 if (optval)
 530                                         u->debug_level = atoi(optval);
 531                                 else
 532                                         u->debug_level++;
 533                         } else if (!strcasecmp(optname, "games") && optval) {
 534                                 u->games = atoi(optval);
 535                         } else if (!strcasecmp(optname, "gamelen") && optval) {
 536                                 u->gamelen = atoi(optval);
 537                         } else if (!strcasecmp(optname, "expand_p") && optval) {
 538                                 u->expand_p = atoi(optval);
 539                         } else if (!strcasecmp(optname, "radar_d") && optval) {
 540                                 /* For 19x19, it is good idea to set this to 3. */
 541                                 u->radar_d = atoi(optval);
 542                         } else if (!strcasecmp(optname, "dumpthres") && optval) {
 543                                 u->dumpthres = atoi(optval);
 544                         } else if (!strcasecmp(optname, "playout_amaf")) {
 545                                 /* Whether to include random playout moves in
 546                                  * AMAF as well. (Otherwise, only tree moves
 547                                  * are included in AMAF. Of course makes sense
 548                                  * only in connection with an AMAF policy.) */
 549                                 /* with-without: 55.5% (+-4.1) */
 550                                 if (optval && *optval == '0')
 551                                         u->playout_amaf = false;
 552                                 else
 553                                         u->playout_amaf = true;
 554                         } else if (!strcasecmp(optname, "playout_amaf_nakade")) {
 555                                 /* Whether to include nakade moves from playouts
 556                                  * in the AMAF statistics; this tends to nullify
 557                                  * the playout_amaf effect by adding too much
 558                                  * noise. */
 559                                 if (optval && *optval == '0')
 560                                         u->playout_amaf_nakade = false;
 561                                 else
 562                                         u->playout_amaf_nakade = true;
 563                         } else if (!strcasecmp(optname, "playout_amaf_cutoff") && optval) {
 564                                 /* Keep only first N% of playout stage AMAF
 565                                  * information. */
 566                                 u->playout_amaf_cutoff = atoi(optval);
 567                         } else if (!strcasecmp(optname, "policy") && optval) {
 568                                 char *policyarg = strchr(optval, ':');
 569                                 if (policyarg)
 570                                         *policyarg++ = 0;
 571                                 if (!strcasecmp(optval, "ucb1")) {
 572                                         u->policy = policy_ucb1_init(u, policyarg);
 573                                 } else if (!strcasecmp(optval, "ucb1tuned")) {
 574                                         u->policy = policy_ucb1tuned_init(u, policyarg);
 575                                 } else if (!strcasecmp(optval, "ucb1amaf")) {
 576                                         u->policy = policy_ucb1amaf_init(u, policyarg);
 577                                 } else {
 578                                         fprintf(stderr, "UCT: Invalid tree policy %s\n", optval);
 579                                 }
 580                         } else if (!strcasecmp(optname, "playout") && optval) {
 581                                 char *playoutarg = strchr(optval, ':');
 582                                 if (playoutarg)
 583                                         *playoutarg++ = 0;
 584                                 if (!strcasecmp(optval, "moggy")) {
 585                                         u->playout = playout_moggy_init(playoutarg);
 586                                 } else if (!strcasecmp(optval, "light")) {
 587                                         u->playout = playout_light_init(playoutarg);
 588                                 } else {
 589                                         fprintf(stderr, "UCT: Invalid playout policy %s\n", optval);
 590                                 }
 591                         } else if (!strcasecmp(optname, "prior") && optval) {
 592                                 u->eqex = atoi(optval);
 593                         } else if (!strcasecmp(optname, "prior_even") && optval) {
 594                                 u->even_eqex = atoi(optval);
 595                         } else if (!strcasecmp(optname, "prior_gp") && optval) {
 596                                 u->gp_eqex = atoi(optval);
 597                         } else if (!strcasecmp(optname, "prior_policy") && optval) {
 598                                 u->policy_eqex = atoi(optval);
 599                         } else if (!strcasecmp(optname, "prior_b19") && optval) {
 600                                 u->b19_eqex = atoi(optval);
 601                         } else if (!strcasecmp(optname, "prior_cfgd") && optval) {
 602                                 u->cfgd_eqex = atoi(optval);
 603                         } else if (!strcasecmp(optname, "amaf_prior") && optval) {
 604                                 u->amaf_prior = atoi(optval);
 605                         } else if (!strcasecmp(optname, "threads") && optval) {
 606                                 u->threads = atoi(optval);
 607                         } else if (!strcasecmp(optname, "force_seed") && optval) {
 608                                 u->force_seed = atoi(optval);
 609                         } else if (!strcasecmp(optname, "no_book")) {
 610                                 u->no_book = true;
 611                         } else {
 612                                 fprintf(stderr, "uct: Invalid engine argument %s or missing value\n", optname);
 613                         }
 614                 }
 615         }
 616
 617         if (u->even_eqex < 0) u->even_eqex = u->eqex;
 618         if (u->gp_eqex < 0) u->gp_eqex = u->eqex;
 619         if (u->policy_eqex < 0) u->policy_eqex = u->eqex;
 620         if (u->b19_eqex < 0) u->b19_eqex = u->eqex;
 621         if (u->cfgd_eqex < 0) u->cfgd_eqex = u->eqex;
 622
 623         u->resign_ratio = 0.2; /* Resign when most games are lost. */
 624         u->loss_threshold = 0.85; /* Stop reading if after at least 5000 playouts this is best value. */
 625         if (!u->policy)
 626                 u->policy = policy_ucb1amaf_init(u, NULL);
 627
 628         if (!u->playout)
 629                 u->playout = playout_moggy_init(NULL);
 630         u->playout->debug_level = u->debug_level;
 631
 632         return u;
 633 }
 634
 635
 636 struct engine *
 637 engine_uct_init(char *arg)
 638 {
 639         struct uct *u = uct_state_init(arg);
 640         struct engine *e = calloc(1, sizeof(struct engine));
 641         e->name = "UCT Engine";
 642         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 capture all dead stones before passing; it will not cost you points (area scoring is used).";
 643         e->genmove = uct_genmove;
 644         e->notify_play = uct_notify_play;
 645         e->data = u;
 646
 647         return e;
 648 }