🔍 Improve RFP return formula: (staticEval + beta)/2 (#652)

lynx-chess · Feb 14, 2024 · 9b82924 · 9b82924
1 parent 56fb596
commit 9b82924
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/src/Lynx/Search/NegaMax.cs b/src/Lynx/Search/NegaMax.cs
@@ -113,9 +113,10 @@ private int NegaMax(int depth, int ply, int alpha, int beta, bool parentWasNullM
             if (depth <= Configuration.EngineSettings.RFP_MaxDepth)
             {
                 // 🔍 Reverse Futility Pruning (RFP) - https://www.chessprogramming.org/Reverse_Futility_Pruning
+                // Return formula by Ciekce, instead of just returning static eval
                 if (staticEval - (Configuration.EngineSettings.RFP_DepthScalingFactor * depth) >= beta)
                 {
-                    return staticEval;
+                    return (staticEval + beta) / 2;
                 }
 
                 // 🔍 Razoring - Strelka impl (CPW) - https://www.chessprogramming.org/Razoring#Strelka