Revert "doEvenDeeperSearch + tuning"

This reverts commit 98965c139df1483a3d684ee8bc7a60dc4b95efa1.

The increase of depth could lead to search explosions,
most visible with TB.

fixes https://github.com/official-stockfish/Stockfish/issues/4276
closes https://github.com/official-stockfish/Stockfish/pull/4256

Bench: 3872306

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 71c4e8d15a987d9c4c6302feb75d8b76aaa706d7..6a0fae9e9bac0f3f58a412f8e415e014b6e509dc 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -1063,7 +1063,7 @@ Value Eval::evaluate(const Position& pos, int* complexity) {
   else
   {
       int nnueComplexity;
-      int scale = 1076 + 96 * pos.non_pawn_material() / 5120;
+      int scale = 1064 + 106 * pos.non_pawn_material() / 5120;
 
       Color stm = pos.side_to_move();
       Value optimism = pos.this_thread()->optimism[stm];
@@ -1071,21 +1071,21 @@ Value Eval::evaluate(const Position& pos, int* complexity) {
       Value nnue = NNUE::evaluate(pos, true, &nnueComplexity);
 
       // Blend nnue complexity with (semi)classical complexity
-      nnueComplexity = (  412 * nnueComplexity
-                        + 428 * abs(psq - nnue)
+      nnueComplexity = (  416 * nnueComplexity
+                        + 424 * abs(psq - nnue)
                         + (optimism  > 0 ? int(optimism) * int(psq - nnue) : 0)
-                        ) / 1026;
+                        ) / 1024;
 
       // Return hybrid NNUE complexity to caller
       if (complexity)
           *complexity = nnueComplexity;
 
-      optimism = optimism * (278 + nnueComplexity) / 256;
-      v = (nnue * scale + optimism * (scale - 755)) / 1024;
+      optimism = optimism * (269 + nnueComplexity) / 256;
+      v = (nnue * scale + optimism * (scale - 754)) / 1024;
   }
 
   // Damp down the evaluation linearly when shuffling
-  v = v * (197 - pos.rule50_count()) / 214;
+  v = v * (195 - pos.rule50_count()) / 211;
 
   // Guarantee evaluation does not hit the tablebase range
   v = std::clamp(v, VALUE_TB_LOSS_IN_MAX_PLY + 1, VALUE_TB_WIN_IN_MAX_PLY - 1);

diff --git a/src/search.cpp b/src/search.cpp
index b2a5b9401bef1dc6b92786eca7b615cdc00810bd..b58a344a597b61103c809706c4893aff48451553 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -81,7 +81,7 @@ namespace {
 
   // History and stats update bonus, based on depth
   int stat_bonus(Depth d) {
-    return std::min((12 * d + 282) * d - 349 , 1480);
+    return std::min((12 * d + 282) * d - 349 , 1594);
   }
 
   // Add a small random component to draw evaluations to avoid 3-fold blindness
@@ -1175,7 +1175,7 @@ moves_loop: // When in check, search starts here
                          - 4433;
 
           // Decrease/increase reduction for moves with a good/bad history (~30 Elo)
-          r -= ss->statScore / (13000 + 4152 * (depth > 7 && depth < 19));
+          r -= ss->statScore / (13628 + 4000 * (depth > 7 && depth < 19));
 
           // In general we want to cap the LMR depth search at newDepth, but when
           // reduction is negative, we allow this move a limited search extension
@@ -1190,10 +1190,9 @@ moves_loop: // When in check, search starts here
               // Adjust full depth search based on LMR results - if result
               // was good enough search deeper, if it was bad enough search shallower
               const bool doDeeperSearch = value > (alpha + 64 + 11 * (newDepth - d));
-              const bool doEvenDeeperSearch = value > alpha + 582;
               const bool doShallowerSearch = value < bestValue + newDepth;
 
-              newDepth += doDeeperSearch - doShallowerSearch + doEvenDeeperSearch;
+              newDepth += doDeeperSearch - doShallowerSearch;
 
               if (newDepth > d)
                   value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode);