Add capture pruning based on SEE heuristic.

alcides-schulz · alcides-schulz · commit 43ba000f3fbe · 2024-03-27T08:05:02.000-04:00
10s+0.1
Score of tucanoNEW vs tucanoOLD: 497 - 417 - 1083  [0.520] 1997
Elo difference: 13.9 +/- 10.3, LOS: 99.6 %, DrawRatio: 54.2 %
SPRT: llr 2.97 (100.7%), lbound -2.94, ubound 2.94 - H1 was accepted

60s+0.6
Score of tucanoNEW vs tucanoOLD: 658 - 583 - 1648  [0.513] 2889
Elo difference: 9.0 +/- 8.3, LOS: 98.3 %, DrawRatio: 57.0 %
SPRT: llr 2.96 (100.5%), lbound -2.94, ubound 2.94 - H1 was accepted
diff --git a/src/main.c b/src/main.c
@@ -20,7 +20,7 @@
 
 #define ENGINE "Tucano"
 #define AUTHOR "Alcides Schulz"
-#define VERSION "11.18"
+#define VERSION "11.19"
 
 void        develop_workbench(void);
 double      bench(int depth, int print);
diff --git a/src/search.c b/src/search.c
@@ -260,6 +260,12 @@ int search(GAME *game, UINT incheck, int alpha, int beta, int depth, MOVE exclud
             }
         }
 
+        if (move_count > 5 && !extensions && !incheck && depth < 5 && !move_is_quiet(move)) {
+            if (best_score + 100 * depth + see_move(&game->board, move) <= alpha) {
+                continue;
+            }
+        }
+
         //  Make move and search new position.
         make_move(&game->board, move);
 

Original file line number	Diff line number	Diff line change
`@@ -260,6 +260,12 @@ int search(GAME *game, UINT incheck, int alpha, int beta, int depth, MOVE exclud`
`260`	`260`	`}`
`261`	`261`	`}`
`262`	`262`
	`263`	`+ if (move_count > 5 && !extensions && !incheck && depth < 5 && !move_is_quiet(move)) {`
	`264`	`+ if (best_score + 100 * depth + see_move(&game->board, move) <= alpha) {`
	`265`	`+ continue;`
	`266`	`+ }`
	`267`	`+ }`
	`268`	`+`
`263`	`269`	`// Make move and search new position.`
`264`	`270`	`make_move(&game->board, move);`
`265`	`271`