uct/policy/ucb1amaf.c

   1 #include <assert.h>
   2 #include <math.h>
   3 #include <stdio.h>
   4 #include <stdlib.h>
   5 #include <string.h>
   6
   7 #include "board.h"
   8 #include "debug.h"
   9 #include "move.h"
  10 #include "random.h"
  11 #include "uct/internal.h"
  12 #include "uct/tree.h"
  13
  14 /* This implements the UCB1 policy with an extra AMAF heuristics. */
  15
  16 struct ucb1_policy_amaf {
  17         /* This is what the Modification of UCT with Patterns in Monte Carlo Go
  18          * paper calls 'p'. Original UCB has this on 2, but this seems to
  19          * produce way too wide searches; reduce this to get deeper and
  20          * narrower readouts - try 0.2. */
  21         float explore_p;
  22         /* First Play Urgency - if set to less than infinity (the MoGo paper
  23          * above reports 1.0 as the best), new branches are explored only
  24          * if none of the existing ones has higher urgency than fpu. */
  25         float fpu;
  26         int urg_randoma, urg_randomm;
  27         float explore_p_rave;
  28         int equiv_rave;
  29         bool both_colors;
  30         bool check_nakade;
  31 };
  32
  33
  34 struct tree_node *ucb1_choose(struct uct_policy *p, struct tree_node *node, struct board *b, enum stone color);
  35
  36 struct tree_node *ucb1_descend(struct uct_policy *p, struct tree *tree, struct tree_node *node, int parity, bool allow_pass);
  37
  38
  39 static inline float fast_sqrt(int x)
  40 {
  41         static const float table[] = {
  42                 0,
  43                 1,
  44                 1.41421356237309504880,
  45                 1.73205080756887729352,
  46                 2.00000000000000000000,
  47         };
  48         //printf("sqrt %d\n", x);
  49         if (x < sizeof(table) / sizeof(*table)) {
  50                 return table[x];
  51         } else {
  52                 return sqrt(x);
  53         }
  54 }
  55
  56 /* Sylvain RAVE function */
  57 struct tree_node *
  58 ucb1srave_descend(struct uct_policy *p, struct tree *tree, struct tree_node *node, int parity, bool allow_pass)
  59 {
  60         struct ucb1_policy_amaf *b = p->data;
  61         float rave_coef = 1.0f / b->equiv_rave;
  62         float nconf = 1.f, rconf = 1.f;
  63         if (b->explore_p > 0)
  64                 nconf = sqrt(log(node->u.playouts + node->prior.playouts));
  65         if (b->explore_p_rave > 0 && node->amaf.playouts)
  66                 rconf = sqrt(log(node->amaf.playouts + node->prior.playouts));
  67
  68         // XXX: Stack overflow danger on big boards?
  69         struct tree_node *nbest[512] = { node->children }; int nbests = 1;
  70         float best_urgency = -9999;
  71
  72         for (struct tree_node *ni = node->children; ni; ni = ni->sibling) {
  73                 /* Do not consider passing early. */
  74                 if (likely(!allow_pass) && unlikely(is_pass(ni->coord)))
  75                         continue;
  76
  77                 /* TODO: Exploration? */
  78
  79                 int ngames = ni->u.playouts;
  80                 int nwins = ni->u.wins;
  81                 int rgames = ni->amaf.playouts;
  82                 int rwins = ni->amaf.wins;
  83                 if (p->uct->amaf_prior) {
  84                         rgames += ni->prior.playouts;
  85                         rwins += ni->prior.wins;
  86                 } else {
  87                         ngames += ni->prior.playouts;
  88                         nwins += ni->prior.wins;
  89                 }
  90                 if (tree_parity(tree, parity) < 0) {
  91                         nwins = ngames - nwins;
  92                         rwins = rgames - rwins;
  93                 }
  94                 float nval = 0, rval = 0;
  95                 if (ngames) {
  96                         nval = (float) nwins / ngames;
  97                         if (b->explore_p > 0)
  98                                 nval += b->explore_p * nconf / fast_sqrt(ngames);
  99                 }
 100                 if (rgames) {
 101                         rval = (float) rwins / rgames;
 102                         if (b->explore_p_rave > 0 && !is_pass(ni->coord))
 103                                 rval += b->explore_p_rave * rconf / fast_sqrt(rgames);
 104                 }
 105
 106                 /* XXX: We later compare urgency with best_urgency; this can
 107                  * be difficult given that urgency can be in register with
 108                  * higher precision than best_urgency, thus even though
 109                  * the numbers are in fact the same, urgency will be
 110                  * slightly higher (or lower). Thus, we declare urgency
 111                  * as volatile, attempting to force the compiler to keep
 112                  * everything as a float. Ideally, we should do some random
 113                  * __FLT_EPSILON__ magic instead. */
 114                 volatile float urgency;
 115                 if (ngames) {
 116                         if (rgames) {
 117                                 /* At the beginning, beta is at 1 and RAVE is used.
 118                                  * At b->equiv_rate, beta is at 1/3 and gets steeper on. */
 119                                 float beta = (float) rgames / (rgames + ngames + rave_coef * ngames * rgames);
 120 #if 0
 121                                 //if (node->coord == 7*11+4) // D7
 122                                 fprintf(stderr, "[beta %f = %d / (%d + %d + %f)]\n",
 123                                         beta, rgames, rgames, ngames, rave_coef * ngames * rgames);
 124 #endif
 125                                 urgency = beta * rval + (1 - beta) * nval;
 126                         } else {
 127                                 urgency = nval;
 128                         }
 129                 } else if (rgames) {
 130                         urgency = rval;
 131                 } else {
 132                         /* assert(!u->even_eqex); */
 133                         urgency = b->fpu;
 134                 }
 135
 136 #if 0
 137                 struct board bb; bb.size = 11;
 138                 //if (node->coord == 7*11+4) // D7
 139                 fprintf(stderr, "%s<%lld>-%s<%lld> urgency %f (r %d / %d, n %d / %d)\n",
 140                         coord2sstr(ni->parent->coord, &bb), ni->parent->hash,
 141                         coord2sstr(ni->coord, &bb), ni->hash, urgency,
 142                         rwins, rgames, nwins, ngames);
 143 #endif
 144                 if (b->urg_randoma)
 145                         urgency += (float)(fast_random(b->urg_randoma) - b->urg_randoma / 2) / 1000;
 146                 if (b->urg_randomm)
 147                         urgency *= (float)(fast_random(b->urg_randomm) + 5) / b->urg_randomm;
 148
 149                 if (urgency > best_urgency) {
 150                         best_urgency = urgency; nbests = 0;
 151                 }
 152                 if (urgency >= best_urgency) {
 153                         /* We want to always choose something else than a pass
 154                          * in case of a tie. pass causes degenerative behaviour. */
 155                         if (nbests == 1 && is_pass(nbest[0]->coord)) {
 156                                 nbests--;
 157                         }
 158                         nbest[nbests++] = ni;
 159                 }
 160         }
 161 #if 0
 162         struct board bb; bb.size = 11;
 163         fprintf(stderr, "[%s %d: ", coord2sstr(node->coord, &bb), nbests);
 164         for (int zz = 0; zz < nbests; zz++)
 165                 fprintf(stderr, "%s", coord2sstr(nbest[zz]->coord, &bb));
 166         fprintf(stderr, "]\n");
 167 #endif
 168         return nbest[fast_random(nbests)];
 169 }
 170
 171 static void
 172 update_node(struct uct_policy *p, struct tree_node *node, int result)
 173 {
 174         node->u.playouts++;
 175         node->u.wins += result;
 176         tree_update_node_value(node, p->uct->amaf_prior);
 177 }
 178
 179 static void
 180 update_node_amaf(struct uct_policy *p, struct tree_node *node, int result)
 181 {
 182         node->amaf.playouts++;
 183         node->amaf.wins += result;
 184         tree_update_node_rvalue(node, p->uct->amaf_prior);
 185 }
 186
 187 void
 188 ucb1amaf_update(struct uct_policy *p, struct tree *tree, struct tree_node *node, enum stone node_color, enum stone player_color, struct playout_amafmap *map, int result)
 189 {
 190         struct ucb1_policy_amaf *b = p->data;
 191         enum stone child_color = stone_other(node_color);
 192
 193 #if 0
 194         struct board bb; bb.size = 9+2;
 195         for (struct tree_node *ni = node; ni; ni = ni->parent)
 196                 fprintf(stderr, "%s ", coord2sstr(ni->coord, &bb));
 197         fprintf(stderr, "[color %d] update result %d (color %d)\n",
 198                         node_color, result, player_color);
 199 #endif
 200
 201         while (node) {
 202                 if (node->parent == NULL)
 203                         assert(tree->root_color == stone_other(child_color));
 204
 205                 update_node(p, node, result);
 206                 if (amaf_nakade(map->map[node->coord]))
 207                         amaf_op(map->map[node->coord], -);
 208
 209                 /* This loop ignores symmetry considerations, but they should
 210                  * matter only at a point when AMAF doesn't help much. */
 211                 for (struct tree_node *ni = node->children; ni; ni = ni->sibling) {
 212                         assert(map->map[ni->coord] != S_OFFBOARD);
 213                         if (map->map[ni->coord] == S_NONE)
 214                                 continue;
 215                         assert(map->game_baselen >= 0);
 216                         enum stone amaf_color = map->map[ni->coord];
 217                         if (amaf_nakade(map->map[ni->coord])) {
 218                                 if (!b->check_nakade)
 219                                         continue;
 220                                 /* We don't care to implement both_colors
 221                                  * properly since it sucks anyway. */
 222                                 int i;
 223                                 for (i = map->game_baselen; i < map->gamelen; i++)
 224                                         if (map->game[i].coord == ni->coord
 225                                             && map->game[i].color == child_color)
 226                                                 break;
 227                                 if (i == map->gamelen)
 228                                         continue;
 229                                 amaf_color = child_color;
 230                         }
 231
 232                         int nres = result;
 233                         if (amaf_color != child_color) {
 234                                 if (!b->both_colors)
 235                                         continue;
 236                                 nres = !nres;
 237                         }
 238                         /* For child_color != player_color, we still want
 239                          * to record the result unmodified; in that case,
 240                          * we will correctly negate them at the descend phase. */
 241
 242                         update_node_amaf(p, ni, nres);
 243
 244 #if 0
 245                         fprintf(stderr, "* %s<%lld> -> %s<%lld> [%d %d => %d/%d]\n", coord2sstr(node->coord, &bb), node->hash, coord2sstr(ni->coord, &bb), ni->hash, player_color, child_color, result);
 246 #endif
 247                 }
 248
 249                 if (!is_pass(node->coord)) {
 250                         map->game_baselen--;
 251                 }
 252                 node = node->parent; child_color = stone_other(child_color);
 253         }
 254 }
 255
 256
 257 struct uct_policy *
 258 policy_ucb1amaf_init(struct uct *u, char *arg)
 259 {
 260         struct uct_policy *p = calloc(1, sizeof(*p));
 261         struct ucb1_policy_amaf *b = calloc(1, sizeof(*b));
 262         p->uct = u;
 263         p->data = b;
 264         p->descend = ucb1srave_descend;
 265         p->choose = ucb1_choose;
 266         p->update = ucb1amaf_update;
 267         p->wants_amaf = true;
 268
 269         // RAVE: 0.2vs0: 40% (+-7.3) 0.1vs0: 54.7% (+-3.5)
 270         b->explore_p = 0.1;
 271         b->explore_p_rave = 0.01;
 272         b->equiv_rave = 3000;
 273         b->fpu = INFINITY;
 274         b->check_nakade = true;
 275
 276         if (arg) {
 277                 char *optspec, *next = arg;
 278                 while (*next) {
 279                         optspec = next;
 280                         next += strcspn(next, ":");
 281                         if (*next) { *next++ = 0; } else { *next = 0; }
 282
 283                         char *optname = optspec;
 284                         char *optval = strchr(optspec, '=');
 285                         if (optval) *optval++ = 0;
 286
 287                         if (!strcasecmp(optname, "explore_p")) {
 288                                 b->explore_p = atof(optval);
 289                         } else if (!strcasecmp(optname, "fpu") && optval) {
 290                                 b->fpu = atof(optval);
 291                         } else if (!strcasecmp(optname, "urg_randoma") && optval) {
 292                                 b->urg_randoma = atoi(optval);
 293                         } else if (!strcasecmp(optname, "urg_randomm") && optval) {
 294                                 b->urg_randomm = atoi(optval);
 295                         } else if (!strcasecmp(optname, "explore_p_rave") && optval) {
 296                                 b->explore_p_rave = atof(optval);
 297                         } else if (!strcasecmp(optname, "equiv_rave") && optval) {
 298                                 b->equiv_rave = atof(optval);
 299                         } else if (!strcasecmp(optname, "both_colors")) {
 300                                 b->both_colors = true;
 301                         } else if (!strcasecmp(optname, "check_nakade")) {
 302                                 b->check_nakade = !optval || *optval == '1';
 303                         } else {
 304                                 fprintf(stderr, "ucb1: Invalid policy argument %s or missing value\n", optname);
 305                         }
 306                 }
 307         }
 308
 309         if (b->explore_p_rave < 0) b->explore_p_rave = b->explore_p;
 310
 311         return p;
 312 }