simplified and increased threshold to switch between NNUE and classical

STC https://tests.stockfishchess.org/tests/view/5f2deb1661e3b6af6488200f
LLR: 2.96 (-2.94,2.94) {-1.50,0.50}
Total: 10376 W: 1481 L: 1359 D: 7536
Ptnml(0-2): 91, 953, 2981, 1069, 94

LTC: https://tests.stockfishchess.org/html/live_elo.html?5f2e0a0461e3b6af64882019
LLR: 2.99 (-2.94,2.94) {-1.50,0.50}
Total: 5040 W: 375 L: 315 D: 4350
Ptnml(0-2): 7, 263, 1926, 311, 13

closes https://github.com/official-stockfish/Stockfish/pull/2934

Bench: 4067325

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 47b84ee62840965eb458c19a4901a0a1defb2db0..1ae6cb3ac56f88d91ca8d56be259505d2a5f35e5 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -110,7 +110,7 @@ namespace {
   constexpr Value LazyThreshold1 =  Value(1400);
   constexpr Value LazyThreshold2 =  Value(1300);
   constexpr Value SpaceThreshold = Value(12222);
-  constexpr Value NNUEThreshold  =   Value(500);
+  constexpr Value NNUEThreshold  =   Value(520);
 
   // KingAttackWeights[PieceType] contains king attack weights by piece type
   constexpr int KingAttackWeights[PIECE_TYPE_NB] = { 0, 0, 81, 52, 44, 10 };
@@ -939,10 +939,9 @@ Value Eval::evaluate(const Position& pos) {
 
   if (Eval::useNNUE)
   {
-      Value balance = pos.non_pawn_material(WHITE) - pos.non_pawn_material(BLACK);
-      balance += 200 * (pos.count<PAWN>(WHITE) - pos.count<PAWN>(BLACK));
+      Value v = eg_value(pos.psq_score());
       // Take NNUE eval only on balanced positions
-      if (abs(balance) < NNUEThreshold)
+      if (abs(v) < NNUEThreshold)
          return NNUE::evaluate(pos) + Tempo;
   }
   return Evaluation<NO_TRACE>(pos).value();

diff --git a/src/search.cpp b/src/search.cpp
index 4a9bd7de047cea9911d9b55a4702fab07145a95b..4a993b017542cd84b6cd159f4a5f64e0feee9dd4 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1134,7 +1134,7 @@ moves_loop: // When in check, search starts from here
       // Castling extension
       if (type_of(move) == CASTLING)
           extension = 1;
-         
+
       // Late irreversible move extension
       if (   move == ttMove
           && pos.rule50_count() > 80