uct/dynkomi.c

   1 #define DEBUG
   2 #include <assert.h>
   3 #include <math.h>
   4 #include <stdio.h>
   5 #include <stdlib.h>
   6 #include <string.h>
   7
   8 #include "board.h"
   9 #include "debug.h"
  10 #include "tactics.h"
  11 #include "uct/dynkomi.h"
  12 #include "uct/internal.h"
  13 #include "uct/tree.h"
  14
  15
  16 static void
  17 generic_done(struct uct_dynkomi *d)
  18 {
  19         if (d->data) free(d->data);
  20         free(d);
  21 }
  22
  23
  24 /* NONE dynkomi strategy - never fiddle with komi values. */
  25
  26 struct uct_dynkomi *
  27 uct_dynkomi_init_none(struct uct *u, char *arg, struct board *b)
  28 {
  29         struct uct_dynkomi *d = calloc(1, sizeof(*d));
  30         d->uct = u;
  31         d->permove = NULL;
  32         d->persim = NULL;
  33         d->done = generic_done;
  34         d->data = NULL;
  35
  36         if (arg) {
  37                 fprintf(stderr, "uct: Dynkomi method none accepts no arguments\n");
  38                 exit(1);
  39         }
  40
  41         return d;
  42 }
  43
  44
  45 /* LINEAR dynkomi strategy - Linearly Decreasing Handicap Compensation. */
  46 /* At move 0, we impose extra komi of handicap_count*handicap_value, then
  47  * we linearly decrease this extra komi throughout the game down to 0
  48  * at @moves moves. */
  49
  50 struct dynkomi_linear {
  51         int handicap_value;
  52         int moves;
  53         bool rootbased;
  54 };
  55
  56 static float
  57 linear_permove(struct uct_dynkomi *d, struct board *b, struct tree *tree)
  58 {
  59         struct dynkomi_linear *l = d->data;
  60         if (b->moves >= l->moves)
  61                 return 0;
  62
  63         float base_komi = board_effective_handicap(b, l->handicap_value);
  64         float extra_komi = base_komi * (l->moves - b->moves) / l->moves;
  65         return extra_komi;
  66 }
  67
  68 static float
  69 linear_persim(struct uct_dynkomi *d, struct board *b, struct tree *tree, struct tree_node *node)
  70 {
  71         struct dynkomi_linear *l = d->data;
  72         if (l->rootbased)
  73                 return tree->extra_komi;
  74         /* We don't reuse computed value from tree->extra_komi,
  75          * since we want to use value correct for this node depth.
  76          * This also means the values will stay correct after
  77          * node promotion. */
  78         return linear_permove(d, b, tree);
  79 }
  80
  81 struct uct_dynkomi *
  82 uct_dynkomi_init_linear(struct uct *u, char *arg, struct board *b)
  83 {
  84         struct uct_dynkomi *d = calloc(1, sizeof(*d));
  85         d->uct = u;
  86         d->permove = linear_permove;
  87         d->persim = linear_persim;
  88         d->done = generic_done;
  89
  90         struct dynkomi_linear *l = calloc(1, sizeof(*l));
  91         d->data = l;
  92
  93         if (board_size(b) - 2 >= 19)
  94                 l->moves = 200;
  95         l->handicap_value = 7;
  96
  97         if (arg) {
  98                 char *optspec, *next = arg;
  99                 while (*next) {
 100                         optspec = next;
 101                         next += strcspn(next, ":");
 102                         if (*next) { *next++ = 0; } else { *next = 0; }
 103
 104                         char *optname = optspec;
 105                         char *optval = strchr(optspec, '=');
 106                         if (optval) *optval++ = 0;
 107
 108                         if (!strcasecmp(optname, "moves") && optval) {
 109                                 /* Dynamic komi in handicap game; linearly
 110                                  * decreases to basic settings until move
 111                                  * #optval. */
 112                                 l->moves = atoi(optval);
 113                         } else if (!strcasecmp(optname, "handicap_value") && optval) {
 114                                 /* Point value of single handicap stone,
 115                                  * for dynkomi computation. */
 116                                 l->handicap_value = atoi(optval);
 117                         } else if (!strcasecmp(optname, "rootbased")) {
 118                                 /* If set, the extra komi applied will be
 119                                  * the same for all simulations within a move,
 120                                  * instead of being same for all simulations
 121                                  * within the tree node. */
 122                                 l->rootbased = !optval || atoi(optval);
 123                         } else {
 124                                 fprintf(stderr, "uct: Invalid dynkomi argument %s or missing value\n", optname);
 125                                 exit(1);
 126                         }
 127                 }
 128         }
 129
 130         return d;
 131 }
 132
 133
 134 /* ADAPTIVE dynkomi strategy - Adaptive Situational Compensation */
 135 /* We adapt the komi based on current situation:
 136  * (i) score-based: We maintain the average score outcome of our
 137  * games and adjust the komi by a fractional step towards the expected
 138  * score;
 139  * (ii) value-based: While winrate is above given threshold, adjust
 140  * the komi by a fixed step in the appropriate direction.
 141  * These adjustments can be
 142  * (a) Move-stepped, new extra komi value is always set only at the
 143  * beginning of the tree search for next move;
 144  * (b) Continuous, new extra komi value is periodically re-determined
 145  * and adjusted throughout a single tree search. */
 146
 147 struct dynkomi_adaptive {
 148         /* Do not take measured average score into regard for
 149          * first @lead_moves - the variance is just too much.
 150          * (Instead, we consider the handicap-based komi provided
 151          * by linear dynkomi.) */
 152         int lead_moves;
 153         /* Maximum komi to pretend the opponent to give. */
 154         float max_losing_komi;
 155         float (*indicator)(struct dynkomi_adaptive *a, struct board *b, struct tree *tree);
 156
 157         /* Value-based adaptation. */
 158         float zone_red, zone_green;
 159         int score_step;
 160         bool use_komi_latch;
 161         float komi_latch; // runtime, not configuration
 162
 163         /* Score-based adaptation. */
 164         float (*adapter)(struct dynkomi_adaptive *a, struct board *b);
 165         float adapt_base; // [0,1)
 166         /* Sigmoid adaptation rate parameter; see below for details. */
 167         float adapt_phase; // [0,1]
 168         float adapt_rate; // [1,infty)
 169         bool adapt_aport; // alternative game portion determination
 170         /* Linear adaptation rate parameter. */
 171         int adapt_moves;
 172         float adapt_dir; // [-1,1]
 173 };
 174 #define TRUSTWORTHY_KOMI_PLAYOUTS 200
 175
 176 static float
 177 adapter_sigmoid(struct dynkomi_adaptive *a, struct board *b)
 178 {
 179         /* Figure out how much to adjust the komi based on the game
 180          * stage. The adaptation rate is 0 at the beginning,
 181          * at game stage a->adapt_phase crosses though 0.5 and
 182          * approaches 1 at the game end; the slope is controlled
 183          * by a->adapt_rate. */
 184         float game_portion;
 185         if (!a->adapt_aport) {
 186                 int total_moves = b->moves + 2 * board_estimated_moves_left(b);
 187                 game_portion = (float) b->moves / total_moves;
 188         } else {
 189                 int brsize = board_size(b) - 2;
 190                 game_portion = 1.0 - (float) b->flen / (brsize * brsize);
 191         }
 192         float l = game_portion - a->adapt_phase;
 193         return 1.0 / (1.0 + exp(-a->adapt_rate * l));
 194 }
 195
 196 static float
 197 adapter_linear(struct dynkomi_adaptive *a, struct board *b)
 198 {
 199         /* Figure out how much to adjust the komi based on the game
 200          * stage. We just linearly increase/decrease the adaptation
 201          * rate for first N moves. */
 202         if (b->moves > a->adapt_moves)
 203                 return 0;
 204         if (a->adapt_dir < 0)
 205                 return 1 - (- a->adapt_dir) * b->moves / a->adapt_moves;
 206         else
 207                 return a->adapt_dir * b->moves / a->adapt_moves;
 208 }
 209
 210 static float
 211 komi_by_score(struct dynkomi_adaptive *a, struct board *b, struct tree *tree)
 212 {
 213         if (tree->score.playouts < TRUSTWORTHY_KOMI_PLAYOUTS)
 214                 return tree->extra_komi;
 215
 216         struct move_stats score = tree->score;
 217         /* Almost-reset tree->score to gather fresh stats. */
 218         tree->score.playouts = 1;
 219
 220         /* Look at average score and push extra_komi in that direction. */
 221         float p = a->adapter(a, b);
 222         p = a->adapt_base + p * (1 - a->adapt_base);
 223         if (p > 0.9) p = 0.9; // don't get too eager!
 224         float extra_komi = tree->extra_komi + p * score.value;
 225         if (DEBUGL(3))
 226                 fprintf(stderr, "mC += %f * %f\n", p, score.value);
 227         return extra_komi;
 228 }
 229
 230 static float
 231 komi_by_value(struct dynkomi_adaptive *a, struct board *b, struct tree *tree)
 232 {
 233         if (tree->value.playouts < TRUSTWORTHY_KOMI_PLAYOUTS)
 234                 return tree->extra_komi;
 235
 236         struct move_stats value = tree->value;
 237         /* Almost-reset tree->value to gather fresh stats. */
 238         tree->value.playouts = 1;
 239
 240         /* We have three "value zones":
 241          * red zone | yellow zone | green zone
 242          *        ~45%           ~60%
 243          * red zone: reduce komi
 244          * yellow zone: do not touch komi
 245          * green zone: enlage komi.
 246          *
 247          * Also, at some point komi will be tuned in such way
 248          * that it will be in green zone but increasing it will
 249          * be unfeasible. Thus, we have a _latch_ - we will
 250          * remember the last komi that has put us into the
 251          * red zone, and not use it or go over it. We use the
 252          * latch only when giving extra komi, we always want
 253          * to try to reduce extra komi we take.
 254          *
 255          * TODO: Make the latch expire after a while. */
 256         float extra_komi = tree->extra_komi;
 257
 258         if (value.value < a->zone_red) {
 259                 /* Red zone. Take extra komi. */
 260                 if (DEBUGL(3))
 261                         fprintf(stderr, "[red] %f, komi latch %f -> %f\n",
 262                                 value.value, a->komi_latch, extra_komi);
 263                 if (extra_komi > 0) a->komi_latch = extra_komi;
 264                 extra_komi -= a->score_step; // XXX: we depend on being black
 265                 return extra_komi;
 266
 267         } else if (value.value < a->zone_green) {
 268                 /* Yellow zone, do nothing. */
 269                 return extra_komi;
 270
 271         } else {
 272                 /* Green zone. Give extra komi. */
 273                 extra_komi += a->score_step; // XXX: we depend on being black
 274                 if (DEBUGL(3))
 275                         fprintf(stderr, "[green] %f, += %d | komi latch %f\n",
 276                                 value.value, a->score_step, a->komi_latch);
 277                 return !a->use_komi_latch || extra_komi < a->komi_latch ? extra_komi : a->komi_latch - 1;
 278         }
 279 }
 280
 281 static float
 282 adaptive_permove(struct uct_dynkomi *d, struct board *b, struct tree *tree)
 283 {
 284         struct dynkomi_adaptive *a = d->data;
 285         if (DEBUGL(3))
 286                 fprintf(stderr, "m %d/%d ekomi %f permove %f/%d\n",
 287                         b->moves, a->lead_moves, tree->extra_komi,
 288                         tree->score.value, tree->score.playouts);
 289         if (b->moves <= a->lead_moves)
 290                 return board_effective_handicap(b, 7 /* XXX */);
 291
 292         /* Get lower bound on komi value so that we don't underperform
 293          * too much. XXX: We rely on the fact that we don't use dynkomi
 294          * as white for now. */
 295         float min_komi = - a->max_losing_komi;
 296
 297         float komi = a->indicator(a, b, tree);
 298         if (DEBUGL(3))
 299                 fprintf(stderr, "dynkomi: %f -> %f\n", tree->extra_komi, komi);
 300         return komi > min_komi ? komi : min_komi;
 301 }
 302
 303 static float
 304 adaptive_persim(struct uct_dynkomi *d, struct board *b, struct tree *tree, struct tree_node *node)
 305 {
 306         return tree->extra_komi;
 307 }
 308
 309 struct uct_dynkomi *
 310 uct_dynkomi_init_adaptive(struct uct *u, char *arg, struct board *b)
 311 {
 312         struct uct_dynkomi *d = calloc(1, sizeof(*d));
 313         d->uct = u;
 314         d->permove = adaptive_permove;
 315         d->persim = adaptive_persim;
 316         d->done = generic_done;
 317
 318         struct dynkomi_adaptive *a = calloc(1, sizeof(*a));
 319         d->data = a;
 320
 321         if (board_size(b) - 2 >= 19)
 322                 a->lead_moves = 20;
 323         else
 324                 a->lead_moves = 4; // XXX
 325         a->max_losing_komi = 10;
 326         a->indicator = komi_by_score;
 327
 328         a->adapter = adapter_sigmoid;
 329         a->adapt_rate = 20;
 330         a->adapt_phase = 0.5;
 331         a->adapt_moves = 200;
 332         a->adapt_dir = -0.5;
 333
 334         a->zone_red = 0.45;
 335         a->zone_green = 0.6;
 336         a->score_step = 2;
 337         a->use_komi_latch = true;
 338         a->komi_latch = 1000;
 339
 340         if (arg) {
 341                 char *optspec, *next = arg;
 342                 while (*next) {
 343                         optspec = next;
 344                         next += strcspn(next, ":");
 345                         if (*next) { *next++ = 0; } else { *next = 0; }
 346
 347                         char *optname = optspec;
 348                         char *optval = strchr(optspec, '=');
 349                         if (optval) *optval++ = 0;
 350
 351                         if (!strcasecmp(optname, "lead_moves") && optval) {
 352                                 /* Do not adjust komi adaptively for first
 353                                  * N moves. */
 354                                 a->lead_moves = atoi(optval);
 355                         } else if (!strcasecmp(optname, "max_losing_komi") && optval) {
 356                                 a->max_losing_komi = atof(optval);
 357                         } else if (!strcasecmp(optname, "indicator")) {
 358                                 /* Adaptatation indicator - how to decide
 359                                  * the adaptation rate and direction. */
 360                                 if (!strcasecmp(optval, "value")) {
 361                                         /* Winrate w/ komi so far. */
 362                                         a->indicator = komi_by_value;
 363                                 } else if (!strcasecmp(optval, "score")) {
 364                                         /* Expected score w/ current komi. */
 365                                         a->indicator = komi_by_score;
 366                                 } else {
 367                                         fprintf(stderr, "UCT: Invalid indicator %s\n", optval);
 368                                         exit(1);
 369                                 }
 370
 371                                 /* value indicator settings */
 372                         } else if (!strcasecmp(optname, "zone_red") && optval) {
 373                                 a->zone_red = atof(optval);
 374                         } else if (!strcasecmp(optname, "zone_green") && optval) {
 375                                 a->zone_green = atof(optval);
 376                         } else if (!strcasecmp(optname, "score_step") && optval) {
 377                                 a->score_step = atoi(optval);
 378                         } else if (!strcasecmp(optname, "use_komi_latch")) {
 379                                 a->use_komi_latch = !optval || atoi(optval);
 380
 381                                 /* score indicator settings */
 382                         } else if (!strcasecmp(optname, "adapter") && optval) {
 383                                 /* Adaptatation method. */
 384                                 if (!strcasecmp(optval, "sigmoid")) {
 385                                         a->adapter = adapter_sigmoid;
 386                                 } else if (!strcasecmp(optval, "linear")) {
 387                                         a->adapter = adapter_linear;
 388                                 } else {
 389                                         fprintf(stderr, "UCT: Invalid adapter %s\n", optval);
 390                                         exit(1);
 391                                 }
 392                         } else if (!strcasecmp(optname, "adapt_base") && optval) {
 393                                 /* Adaptation base rate; see above. */
 394                                 a->adapt_base = atof(optval);
 395                         } else if (!strcasecmp(optname, "adapt_rate") && optval) {
 396                                 /* Adaptation slope; see above. */
 397                                 a->adapt_rate = atof(optval);
 398                         } else if (!strcasecmp(optname, "adapt_phase") && optval) {
 399                                 /* Adaptation phase shift; see above. */
 400                                 a->adapt_phase = atof(optval);
 401                         } else if (!strcasecmp(optname, "adapt_moves") && optval) {
 402                                 /* Adaptation move amount; see above. */
 403                                 a->adapt_moves = atoi(optval);
 404                         } else if (!strcasecmp(optname, "adapt_aport")) {
 405                                 a->adapt_aport = !optval || atoi(optval);
 406                         } else if (!strcasecmp(optname, "adapt_dir") && optval) {
 407                                 /* Adaptation direction vector; see above. */
 408                                 a->adapt_dir = atof(optval);
 409
 410                         } else {
 411                                 fprintf(stderr, "uct: Invalid dynkomi argument %s or missing value\n", optname);
 412                                 exit(1);
 413                         }
 414                 }
 415         }
 416
 417         return d;
 418 }