Simplify History LMR Formula

STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 41713 W: 7589 L: 7504 D: 26620

LTC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 41353 W: 5484 L: 5391 D: 30478

Bench: 8946983

diff --git a/src/search.cpp b/src/search.cpp
index 6b8949569f753b38f1f9ee98960d1a8fba7bdaf9..52bb09877e26445428b3958182dd8cfd7bf741b0 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1013,13 +1013,12 @@ moves_loop: // When in check search starts from here
           Value fmValue = (fm ? (*fm)[pos.piece_on(to_sq(move))][to_sq(move)] : VALUE_ZERO);
           Value fm2Value = (fm2 ? (*fm2)[pos.piece_on(to_sq(move))][to_sq(move)] : VALUE_ZERO);
 
           Value fmValue = (fm ? (*fm)[pos.piece_on(to_sq(move))][to_sq(move)] : VALUE_ZERO);
           Value fm2Value = (fm2 ? (*fm2)[pos.piece_on(to_sq(move))][to_sq(move)] : VALUE_ZERO);
 

-          // Increase reduction for cut nodes and moves with a bad history
-          if (   (!PvNode && cutNode)
-              || (hValue < VALUE_ZERO && cmhValue <= VALUE_ZERO))
+          // Increase reduction for cut nodes
+          if (!PvNode && cutNode)

               r += ONE_PLY;
 
           // Decrease/increase reduction for moves with a good/bad history
               r += ONE_PLY;
 
           // Decrease/increase reduction for moves with a good/bad history

-          int rHist = (hValue + cmhValue + fmValue + fm2Value) / 20000;
+          int rHist = (hValue + cmhValue + fmValue + fm2Value - 10000) / 20000;

           r = std::max(DEPTH_ZERO, r - rHist * ONE_PLY);
 
           // Decrease reduction for moves that escape a capture. Filter out
           r = std::max(DEPTH_ZERO, r - rHist * ONE_PLY);
 
           // Decrease reduction for moves that escape a capture. Filter out