[gnugo-devel] escape values patch

[Paul Pogonyshev]

Consider this code snippet from compute_owl_escape_values():

        else if (dragon[pos].crude_status == UNKNOWN
                 && (DRAGON2(pos).escape_route > 5
                     || DRAGON2(pos).moyo_size > 5))
          owl->escape_values[pos] = 4;

In owl1:319 we have the following position:

     A B C D E F G H J K L M N O P Q R S T
  19 . . . . . . . . O X X . X X X X . . . 19
  18 . . . . . . . O . O X X X O O O X . . 18
  17 O O O O . . . . . O X X O O O O X . . 17
  16 X X X O . O . . . O X O O O X X O X . 16
  15 X . X X O . . . . O O X . O X X . . . 15
  14 O X . X O . . . X . . . . O O X . . . 14
  13 . X . X O O O O X O O . . O X . . . . 13
  12 . . . X X X X O O X O O O X . X . X . 12
  11 . . . X O X . X X X X O X . . . . X O 11
  10 . . X X O O X X X O X X . X . X X O . 10
   9 . . X O . . O O X O O X X . . X O O . 9
   8 . . X O . O O O O O O X O . . O . . . 8
   7 . . X O . O X O X X X O O O . O . O . 7
   6 . . X O . O X X . . . X X O X . O . . 6
   5 X X X X O O X . X X X . X O X . . X . 5
   4 O X O O . O O X X O X X . X X X X X X 4
   3 O O O . . O . O O O X X X O X O O O X 3
   2 . . . . . . . . O . O X X O O O . O O 2
   1 . . . . . . . . . O O O X O . . . O . 1
     A B C D E F G H J K L M N O P Q R S T

The dragon at N8 has large escape route because it can escape to S10
dragon.  Because of this, escape values on N8 dragons are equal to 4
during owl reading on S10 dragon.  This causes S10 to have escape live
reasons very early and clearly incorrectly.

This patch revises compute_owl_escape_values() to solve this problem.
The logic is like this: "if dragon B has large escape route only
because it can escape to dragon A, then don't consider dragon B a good
escape target for dragon A".  This only applies when the crude status
of dragon B is UNKNOWN and it's moyo size is not greater than 5.

The fix also required some quite trivial changes in `influence.c' and
`dragon.c'.

There is no regression breakage.  However, there is a major impovement
in the targeted position (owl1:319).  The result of `owl_attack S10'
is now `1 T8' instead of `0'.  The remaining problem has nothing to do
with escape values.

The patch causes a negligible (less than 0.1%) increase in owl node
counters:

before:   1512058690 2466393 8795545
after:    1512155669 2467554 8795393

The regressions are on top of 3.5.2-pre-1

Paul



--- engine/dragon.c.~1.123.~    2003-08-13 00:11:40.000000000 +0000
+++ engine/dragon.c     2003-11-05 22:33:14.000000000 +0000
@@ -1867,7 +1867,7 @@ compute_escape(int pos, int dragon_statu
    * area (2) or EMPTY (1).  Values may change without notice.
    */
   get_lively_stones(OTHER_COLOR(board[pos]), safe_stones);
-  compute_escape_influence(board[pos], safe_stones, 0, escape_value);
+  compute_escape_influence(board[pos], safe_stones, NULL, 0, escape_value);
 
   /* If we can reach a live group, award 6 points. */
   for (ii = BOARDMIN; ii < BOARDMAX; ii++) {
--- engine/influence.c.~1.95.~  2003-08-13 00:18:36.000000000 +0000
+++ engine/influence.c  2003-11-05 18:45:04.000000000 +0000
@@ -1093,6 +1093,7 @@ find_influence_patterns(struct influence
  */
 static void
 do_compute_influence(int color, const char safe_stones[BOARDMAX],
+                    const char inhibited_sources[BOARDMAX],
                     const float strength[BOARDMAX], struct influence_data *q,
                     int move, const char *trace_message)
 {
@@ -1107,7 +1108,7 @@ do_compute_influence(int color, const ch
   modify_depth_values(1 - stackp);
   
   for (ii = BOARDMIN; ii < BOARDMAX; ii++)
-    if (ON_BOARD(ii)) {
+    if (ON_BOARD(ii) && !(inhibited_sources && inhibited_sources[ii])) {
       if (q->white_strength[ii] > 0.0)
        accumulate_influence(q, ii, WHITE);
       if (q->black_strength[ii] > 0.0)
@@ -1164,7 +1165,8 @@ compute_influence(int color, const char 
   influence_id++;
   q->id = influence_id;
 
-  do_compute_influence(color, safe_stones, strength, q, move, trace_message);
+  do_compute_influence(color, safe_stones, NULL, strength,
+                      q, move, trace_message);
 
   debug = save_debug;
 }
@@ -1765,6 +1767,7 @@ compute_followup_influence(const struct 
 
 void
 compute_escape_influence(int color, const char safe_stones[BOARDMAX],
+                        const char goal[BOARDMAX],
                         const float strength[BOARDMAX],
                         char escape_value[BOARDMAX])
 {
@@ -1780,33 +1783,35 @@ compute_escape_influence(int color, cons
   static char escape_values[BOARDMAX][2];
   static int active_caches[2] = {0, 0};
 
-  /* Encode the values of color and dragons_known into an integer
-   * between 0 and 3.
-   */
   int cache_number = (color == WHITE);
 
-  int board_was_cached = 1;
-
-  /* Notice that we compare the out of board markers as well, in case
-   * the board size should have changed between calls.
-   */
-  for (ii = BOARDMIN; ii < BOARDMAX; ii++) {
-    if (cached_board[ii] != board[ii]) {
-      cached_board[ii] = board[ii];
-      board_was_cached = 0;
+  if (!goal) {
+    /* Encode the values of color and dragons_known into an integer
+     * between 0 and 3.
+     */
+    int board_was_cached = 1;
+
+    /* Notice that we compare the out of board markers as well, in
+     * case the board size should have changed between calls.
+     */
+    for (ii = BOARDMIN; ii < BOARDMAX; ii++) {
+      if (cached_board[ii] != board[ii]) {
+       cached_board[ii] = board[ii];
+       board_was_cached = 0;
+      }
     }
-  }
 
-  if (!board_was_cached)
-    for (k = 0; k < 2; k++)
-      active_caches[k] = 0;
-  
-  if (active_caches[cache_number]) {
-    for (ii = BOARDMIN; ii < BOARDMAX; ii++)
-      if (ON_BOARD(ii))
-       escape_value[ii] = escape_values[ii][cache_number];
-    
-    return;
+    if (!board_was_cached)
+      for (k = 0; k < 2; k++)
+       active_caches[k] = 0;
+
+    if (active_caches[cache_number]) {
+      for (ii = BOARDMIN; ii < BOARDMAX; ii++)
+       if (ON_BOARD(ii))
+         escape_value[ii] = escape_values[ii][cache_number];
+
+      return;
+    }
   }
 
   /* Use enhance pattern and higher attenuation for escape influence. */
@@ -1819,7 +1824,7 @@ compute_escape_influence(int color, cons
   if (!(debug & DEBUG_ESCAPE))
     debug &= ~DEBUG_INFLUENCE;
 
-  do_compute_influence(OTHER_COLOR(color), safe_stones, strength,
+  do_compute_influence(OTHER_COLOR(color), safe_stones, goal, strength,
                       &escape_influence, -1, NULL);
 
   debug = save_debug;
@@ -1827,13 +1832,35 @@ compute_escape_influence(int color, cons
   for (ii = BOARDMIN; ii < BOARDMAX; ii++)
     if (ON_BOARD(ii)) {
       if (whose_moyo(&escape_influence, ii) == color)
-       escape_value[ii] = 4;
+       escape_value[ii] = 4;
       else if (whose_area(&escape_influence, ii) == color)
-       escape_value[ii] = 2;
-      else if (whose_area(&escape_influence, ii) == EMPTY)
-       escape_value[ii] = 1;
+       escape_value[ii] = 2;
+      else if (whose_area(&escape_influence, ii) == EMPTY) {
+       if (goal) {
+         escape_value[ii] = 0;
+
+         if (!goal[ii]) {
+           int goal_proximity = 0;
+
+           for (k = 0; k < 8; k++) {
+             if (ON_BOARD(ii + delta[k])) {
+               goal_proximity += 2 * goal[ii + delta[k]];
+               if (k < 4 && ON_BOARD(ii + 2 * delta[k]))
+                 goal_proximity += goal[ii + delta[k]];
+             }
+             else
+               goal_proximity += 1;
+           }
+
+           if (goal_proximity < 6)
+             escape_value[ii] = 1;
+         }
+       }
+       else
+         escape_value[ii] = 1;
+      }
       else
-       escape_value[ii] = 0;
+       escape_value[ii] = 0;
     }
 
   if (0 && (debug & DEBUG_ESCAPE) && verbose > 0) {
@@ -1845,11 +1872,13 @@ compute_escape_influence(int color, cons
                            "%3.0f", 3, 1, 1);
   }    
 
-  /* Save the computed values in the cache. */
-  for (ii = BOARDMIN; ii < BOARDMAX; ii++)
-    if (ON_BOARD(ii))
-      escape_values[ii][cache_number] = escape_value[ii];
-  active_caches[cache_number] = 1;
+  if (!goal) {
+    /* Save the computed values in the cache. */
+    for (ii = BOARDMIN; ii < BOARDMAX; ii++)
+      if (ON_BOARD(ii))
+       escape_values[ii][cache_number] = escape_value[ii];
+    active_caches[cache_number] = 1;
+  }
 }
 
 
--- engine/liberty.h.~1.202.~   2003-09-09 00:00:57.000000000 +0000
+++ engine/liberty.h    2003-11-05 17:44:53.000000000 +0000
@@ -572,6 +572,7 @@ void compute_followup_influence(const st
                                struct influence_data *q, 
                                int move, const char *trace_message);
 void compute_escape_influence(int color, const char safe_stones[BOARDMAX],
+                             const char goal[BOARDMAX],
                              const float strength[BOARDMAX],
                               char escape_value[BOARDMAX]);
 
--- engine/owl.c.~1.179.~       2003-10-22 02:55:54.000000000 +0000
+++ engine/owl.c        2003-11-06 14:19:47.000000000 +0000
@@ -5236,19 +5265,40 @@ compute_owl_escape_values(struct local_o
   char safe_stones[BOARDMAX];
   
   get_lively_stones(OTHER_COLOR(owl->color), safe_stones);
-  compute_escape_influence(owl->color, safe_stones, NULL, owl->escape_values);
-  DEBUG(DEBUG_ESCAPE, "Owl escape values:\n");
+  compute_escape_influence(owl->color, safe_stones, NULL, NULL,
+                          owl->escape_values);
 
+  DEBUG(DEBUG_ESCAPE, "Owl escape values:\n");
   for (m = 0; m < board_size; m++) {
     for (n = 0; n < board_size; n++) {
       pos = POS(m, n);
-      if (dragon[pos].color == owl->color) {
+      if (dragon[pos].color == owl->color && !owl->goal[pos]) {
        if (dragon[pos].crude_status == ALIVE)
          owl->escape_values[pos] = 6;
-       else if (dragon[pos].crude_status == UNKNOWN
-                && (DRAGON2(pos).escape_route > 5
-                    || DRAGON2(pos).moyo_size > 5))
-         owl->escape_values[pos] = 4;
+       else if (dragon[pos].crude_status == UNKNOWN) {
+         if (DRAGON2(pos).moyo_size > 5)
+           owl->escape_values[pos] = 4;
+         else if (DRAGON2(pos).escape_route > 5) {
+           if (pos != DRAGON2(pos).origin)
+             owl->escape_values[pos] = owl->escape_values[DRAGON2(pos).origin];
+           else {
+             int pos2;
+             char escape_values[BOARDMAX];
+             char dragon[BOARDMAX];
+
+             compute_escape_influence(owl->color, safe_stones, owl->goal, NULL,
+                                      escape_values);
+
+             for (pos2 = BOARDMIN; pos2 < BOARDMAX; pos2++) {
+               if (ON_BOARD(pos2))
+                 dragon[pos2] = is_same_dragon(pos2, pos);
+             }
+
+             if (dragon_escape(dragon, owl->color, escape_values) > 5)
+               owl->escape_values[pos] = 4;
+           }
+         }
+       }
       }
       DEBUG(DEBUG_ESCAPE, "%o%d", owl->escape_values[pos]);
     }