Adjust depth based on eval progression.

alcides-schulz · alcides-schulz · commit 812fe83ead04 · 2025-05-13T14:51:07.000-04:00
20s+0.2 Hash=16
Score of tucanoNEW vs tucanoOLD: 1678 - 1595 - 3665  [0.506] 6938
Elo difference: 4.2 +/- 5.6, LOS: 92.7 %, DrawRatio: 52.8 %
SPRT: llr 2.98 (101.1%), lbound -2.94, ubound 2.94 - H1 was accepted

60s+0.6 Hash=64
Score of tucanoNEW vs tucanoOLD: 969 - 890 - 2278  [0.510] 4137
Elo difference: 6.6 +/- 7.1, LOS: 96.7 %, DrawRatio: 55.1 %
SPRT: llr 2.98 (101.1%), lbound -2.94, ubound 2.94 - H1 was accepted
diff --git a/src/globals.h b/src/globals.h
@@ -405,6 +405,7 @@ typedef struct s_game {
     MOVE_ORDER  move_order;
     EVAL_TABLE  eval_table[EVAL_TABLE_SIZE];
     int         eval_hist[MAX_PLY];
+    int         reductions[MAX_PLY];
     int         is_main_thread;
     THREAD_ID   thread_handle;
     int         thread_number;
diff --git a/src/main.c b/src/main.c
@@ -20,7 +20,7 @@
 
 #define ENGINE "Tucano"
 #define AUTHOR "Alcides Schulz"
-#define VERSION "12.11"
+#define VERSION "12.12"
 
 void        develop_workbench(void);
 double      bench(int depth, int print);
diff --git a/src/search.c b/src/search.c
@@ -48,6 +48,7 @@ int search(GAME *game, UINT incheck, int alpha, int beta, int depth, MOVE exclud
 
     game->pv_line.size[ply] = ply;
     game->search.nodes++;
+    game->reductions[ply] = 0;
 
     if (!root_node) {
         // drawn position
@@ -127,6 +128,16 @@ int search(GAME *game, UINT incheck, int alpha, int beta, int depth, MOVE exclud
     int eval_score = evaluate(game);
     game->eval_hist[ply] = eval_score;
     int improving = ply > 1 && game->eval_hist[ply] > game->eval_hist[ply - 2];
+    int opponent_worsening = ply > 0 && game->eval_hist[ply] > -game->eval_hist[ply - 1];
+    int prior_reduction = ply > 0 ? game->reductions[ply - 1] : 0;
+
+    // Adjust depth based on eval progress
+    if (prior_reduction >= 3 && !opponent_worsening) {
+        depth++;
+    }
+    if (prior_reduction >= 1 && depth >= 2 && game->eval_hist[ply] + game->eval_hist[ply - 1] > 175) {
+        depth--;
+    }
 
     if (!pv_node && !incheck && !singular_move_search) {
         
@@ -350,7 +361,9 @@ int search(GAME *game, UINT incheck, int alpha, int beta, int depth, MOVE exclud
             score = -search(game, gives_check, -beta, -alpha, depth - 1 + extensions, MOVE_NONE);
         }
         else {
+            game->reductions[ply] = reductions;
             score = -search(game, gives_check, -alpha - 1, -alpha, depth - 1 + extensions - reductions, MOVE_NONE);
+            game->reductions[ply] = 0;
             if (!game->search.abort && score > alpha && reductions) {
                 score = -search(game, gives_check, -alpha - 1, -alpha, depth - 1 + extensions, MOVE_NONE);
             }
