Index: engine/liberty.h
===================================================================
RCS file: /cvsroot/gnugo/gnugo/engine/liberty.h,v
retrieving revision 1.200
diff -u -r1.200 liberty.h
--- engine/liberty.h	24 Aug 2003 03:04:11 -0000	1.200
+++ engine/liberty.h	30 Aug 2003 06:06:03 -0000
@@ -865,6 +865,7 @@
   int semeai_defense_certain;
   int semeai_attack_point; /* Move found by semeai code to kill dragon       */
   int semeai_attack_certain;
+  int semeai_target;       /* The opponent dragon involved in the semeai     */
   enum dragon_status owl_threat_status; /* CAN_THREATEN_ATTACK/DEFENSE       */
   enum dragon_status owl_status; /* (ALIVE, DEAD, UNKNOWN, CRITICAL, UNCHECKED)    */
   int owl_attack_point;    /* vital point for attack                         */
Index: engine/semeai.c
===================================================================
RCS file: /cvsroot/gnugo/gnugo/engine/semeai.c,v
retrieving revision 1.60
diff -u -r1.60 semeai.c
--- engine/semeai.c	10 Aug 2003 17:56:51 -0000	1.60
+++ engine/semeai.c	30 Aug 2003 06:06:03 -0000
@@ -143,6 +143,7 @@
     int attack_move = PASS_MOVE;
     int defense_certain = 0;
     int attack_certain = 0;
+    int semeai_target = 0;
     
     for (d2 = 0; d2 < num_dragons; d2++) {
       if (semeai_results_first[d1][d2] == -1)
@@ -156,6 +157,7 @@
 	best_defense = semeai_results_first[d1][d2];
 	defense_move = semeai_move[d1][d2];
 	defense_certain = semeai_certain[d1][d2];
+	semeai_target = dragon2[d2].origin;
       }
       if (best_attack < semeai_results_second[d2][d1]
 	  || (best_attack == semeai_results_second[d2][d1]
@@ -163,6 +165,7 @@
 	best_attack = semeai_results_second[d2][d1];
 	attack_move = semeai_move[d2][d1];
 	attack_certain = semeai_certain[d2][d1];
+	semeai_target = dragon2[d2].origin;
       }
     }
     
@@ -174,6 +177,7 @@
 	dragon2[d1].semeai_defense_certain = defense_certain;
 	dragon2[d1].semeai_attack_point = attack_move;
 	dragon2[d1].semeai_attack_certain = attack_certain;
+	dragon2[d1].semeai_target = semeai_target;
       }
       else if (best_attack == 0 && attack_certain)
 	update_status(DRAGON(d1).origin, ALIVE, ALIVE);
@@ -182,6 +186,27 @@
 }
 
 
+/* liberty_of_dragon(pos, origin) returns true if the vertex at (pos) is a
+ * liberty of the dragon with origin at (origin).
+ */
+static int 
+liberty_of_dragon(int pos, int origin)
+{
+  int k;
+  if (pos == NO_MOVE)
+    return 0;
+
+  if (board[pos] != EMPTY)
+    return 0;
+
+  for (k = 0; k < 4; k++)
+    if (ON_BOARD(pos + delta[k]) && dragon[pos + delta[k]].origin == origin)
+      return 1;
+
+  return 0;
+}
+
+
 /* This function adds the semeai related move reasons, using the information
  * stored in the dragon2 array.
  *
@@ -193,6 +218,10 @@
 {
   int other = OTHER_COLOR(color);
   int d;
+  int liberties;
+  int libs[MAXLIBS];
+  int r;
+  int resulta, resultb, semeai_move, s_result_certain;
 
   for (d = 0; d < number_of_dragons; d++)
     if (dragon2[d].semeai && DRAGON(d).status == CRITICAL) {
@@ -201,18 +230,77 @@
 	  && (dragon2[d].owl_defense_point == NO_MOVE
 	      || dragon2[d].semeai_defense_certain >= 
 	         dragon2[d].owl_defense_certain)) {
+	/* My dragon can be defended */
 	add_semeai_move(dragon2[d].semeai_defense_point, dragon2[d].origin);
 	DEBUG(DEBUG_SEMEAI, "Adding semeai defense move for %1m at %1m\n",
 	      DRAGON(d).origin, dragon2[d].semeai_defense_point);
+	if (liberty_of_dragon(dragon2[d].semeai_defense_point,
+			      dragon2[d].semeai_target)
+	    && !liberty_of_dragon(dragon2[d].semeai_defense_point,
+				  dragon2[d].origin)
+	    && !is_self_atari(dragon2[d].semeai_defense_point, color)) {
+	  
+	  /* If this is a move to fill the non-common liberties of the
+	   * target, and is not a ko or snap-back, then we try all
+	   * non-common liberties of the target and add all winning
+	   * moves to the move list.
+	   */
+
+          liberties = findlib(dragon2[d].semeai_target, MAXLIBS, libs);
+
+          for (r = 0; r < liberties; r++) {
+            if (!liberty_of_dragon(libs[r], dragon2[d].origin)
+		&& !is_self_atari(libs[r], color)
+		&& libs[r] != dragon2[d].semeai_defense_point) {
+              owl_analyze_semeai_after_move(libs[r], color,
+					    dragon2[d].semeai_target,
+					    dragon2[d].origin,
+					    &resulta, &resultb, &semeai_move,
+					    1, &s_result_certain);
+              if (resulta == 0 && resultb == 0) {
+	        add_semeai_move(libs[r], dragon2[d].origin);
+	        DEBUG(DEBUG_SEMEAI,
+		      "Adding semeai defense move for %1m at %1m\n",
+		      DRAGON(d).origin, libs[r]);
+	      }
+            }
+	  }
+	}
       }
       else if (DRAGON(d).color == other
 	       && dragon2[d].semeai_attack_point
 	       && (dragon2[d].owl_attack_point == NO_MOVE
 		   || dragon2[d].semeai_attack_certain >= 
 		      dragon2[d].owl_attack_certain)) {
+	/* Your dragon can be attacked */
 	add_semeai_move(dragon2[d].semeai_attack_point, dragon2[d].origin);
 	DEBUG(DEBUG_SEMEAI, "Adding semeai attack move for %1m at %1m\n",
 	      DRAGON(d).origin, dragon2[d].semeai_attack_point);
+	if (liberty_of_dragon(dragon2[d].semeai_attack_point,
+			      dragon2[d].origin)
+	    && !liberty_of_dragon(dragon2[d].semeai_attack_point,
+				  dragon2[d].semeai_target)
+	    && !is_self_atari(dragon2[d].semeai_attack_point, color)) {
+
+          liberties = findlib(dragon2[d].origin, MAXLIBS, libs);
+
+          for (r = 0; r < liberties; r++) {
+            if (!liberty_of_dragon(libs[r], dragon2[d].semeai_target)
+		&& !is_self_atari(libs[r], color)
+		&& libs[r] != dragon2[d].semeai_attack_point) {
+              owl_analyze_semeai_after_move(libs[r], color, dragon2[d].origin,
+					    dragon2[d].semeai_target,
+					    &resulta, &resultb, &semeai_move,
+					    1, &s_result_certain);
+              if (resulta == 0 && resultb == 0) {
+	        add_semeai_move(libs[r], dragon2[d].origin);
+	        DEBUG(DEBUG_SEMEAI,
+		      "Adding semeai attack move for %1m at %1m\n",
+		      DRAGON(d).origin, libs[r]);
+	      }
+            }
+	  }
+	}
       }
     }
 }