Ticket #158: endgame_7_11.2a.diff

engine/liberty.h

@@ -408 +408 @@
 void register_good_attack_threat(int move, int target);
 int is_known_good_attack_threat(int move, int target);
 
+void register_known_safe_move(int move);
+int is_known_safe_move(int move);
+
 int get_attack_threats(int pos, int max_strings, int strings[]);
 int get_defense_threats(int pos, int max_strings, int strings[]);
 void get_saved_worms(int pos, signed char saved[BOARDMAX]);

engine/move_reasons.c

@@ -74 +74 @@
 /* Attack threats that are known to be sente locally. */
 static int known_good_attack_threats[BOARDMAX][MAX_ATTACK_THREATS];
 
+/* Moves that are known to be safe (in the sense that played stones can
+ * be captured, but opponent loses much more when attempting to do so)
+ */
+static int known_safe_moves[BOARDMAX];
 
 /* Helper functions to check conditions in discard rules. */
 typedef int (*discard_condition_fn_ptr)(int pos, int what);
@@ -138 +142 @@
   }
 
   for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
+    known_safe_moves[pos] = 0;
     for (k = 0; k < MAX_ATTACK_THREATS; k++)
       known_good_attack_threats[pos][k] = NO_MOVE;
   }
@@ -2023 +2028 @@
   return 0;
 }
 
+/* Like documented in endgame:980, there are also moves which aren't
+ * safe by themselves, but attempting to capture these stones would
+ * result in a loss for the opponent (typically, by damezumari).
+ * Simple examples include snapbacks, but more complicated ones do
+ * exist. Following functions are helpers for the valuation processing
+ * which deal with such special cases.
+ */
+void
+register_known_safe_move(int move)
+{
+  ASSERT_ON_BOARD1(move);
+  
+  known_safe_moves[move] = 1;
+}
+
+
+int
+is_known_safe_move(int move)
+{
+  ASSERT_ON_BOARD1(move);
+  
+  return known_safe_moves[move];
+}
+
 
 /*
  * Local Variables:

engine/value_moves.c

@@ -1068 +1068 @@
     int tactical_safety = 0;
     if (!ON_BOARD(pos))
       continue;
+    tactical_safety = is_known_safe_move(pos);
       
     for (k = 0; k < MAX_REASONS; k++) {
       int r = move[pos].reason[k];
@@ -2461 +2462 @@
 
   mark_inessential_stones(OTHER_COLOR(color), safe_stones);
 
-  if (move[pos].move_safety == 1 && safe_move(pos, color) != 0) {
+  if (move[pos].move_safety == 1
+      && (is_known_safe_move(pos) || safe_move(pos, color) != 0)) {
     safe_stones[pos] = INFLUENCE_SAVED_STONE;
     strength[pos] = DEFAULT_STRENGTH;
     if (0)

patterns/endgame.db

@@ -444 +444 @@
 ;marginal_eye(*) && proper_eye(a) && max_eye_value(a) > 0
 
 
+Pattern EE201b
+
+?XX                     push deeper on first line.
+O.*
+---
+
+:8,sOXe
+
+?XX
+Oa*
+---
+
+;marginal_eye(a) && proper_eye(*) && max_eye_value(*) > 0
+;&& (safe_omove(*) || oplay_attack(*,a,a))
+
+>if (!safe_omove(*)) known_safe_move(*)
+
+
 Pattern EE202
 
 OXX.           endgame move
@@ -1582 +1600 @@
 X*X     Wedge
 O.X
 
-:8,OXe
+:8,sOXe
 
 B*X
 OaX
 
 ;oplay_attack_either(*,a,a,B)
 
+>if (!safe_omove(*)) known_safe_move(*)
+
 
 Pattern CE31
 # gf New pattern. (3.3.6)

patterns/mkpat.c

@@ -436 +436 @@
   {"adjacent_to_defendable_stone_in_atari", 1, 0, 1.0,
                 "adjacent_to_defendable_stone_in_atari(%s)"},
   {"good_attack_threat",        2, 0, 0.01, "register_good_attack_threat(%s, %s)"},
+  {"known_safe_move",           1, 0, 0.01, "register_known_safe_move(%s)"},
   {"break_mirror_helper",       1, 0, 0.01, "break_mirror_helper(%s, color)"}
 };