`LMP_BaseMovesToTry + (LMP_MovesDepthMultiplier * depth * (improving …

…? 2 : 1))` -> `LMP_BaseMovesToTry + (depth * depth / (improving ? 1 : 2))`
lynx-chess · Jan 8, 2025 · c2135c3 · c2135c3
1 parent 4083bca
commit c2135c3
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Showing 3 changed files with 2 additions and 13 deletions.
diff --git a/src/Lynx/Configuration.cs b/src/Lynx/Configuration.cs
@@ -202,10 +202,7 @@ public int Threads
     public int LMP_MaxDepth { get; set; } = 8;
 
     [SPSA<int>(0, 10, 0.5)]
-    public int LMP_BaseMovesToTry { get; set; } = 1;
-
-    [SPSA<int>(0, 10, 0.5)]
-    public int LMP_MovesDepthMultiplier { get; set; } = 3;
+    public int LMP_BaseMovesToTry { get; set; } = 3;
 
     public int History_MaxMoveValue { get; set; } = 8_192;
 

diff --git a/src/Lynx/Search/NegaMax.cs b/src/Lynx/Search/NegaMax.cs
@@ -320,7 +320,7 @@ void RevertMove()
                     // 🔍 Late Move Pruning (LMP) - all quiet moves can be pruned
                     // after searching the first few given by the move ordering algorithm
                     if (depth <= Configuration.EngineSettings.LMP_MaxDepth
-                        && moveIndex >= Configuration.EngineSettings.LMP_BaseMovesToTry + (Configuration.EngineSettings.LMP_MovesDepthMultiplier * depth * (improving ? 2 : 1))) // Based on formula suggested by Antares
+                        && moveIndex >= Configuration.EngineSettings.LMP_BaseMovesToTry + (depth * depth / (improving ? 1 : 2))) // Based on formula suggested by Antares
                     {
                         RevertMove();
                         break;

diff --git a/src/Lynx/UCIHandler.cs b/src/Lynx/UCIHandler.cs
@@ -478,14 +478,6 @@ private void HandleSetOption(ReadOnlySpan<char> command)
                     }
                     break;
                 }
-            case "lmp_movesdepthmultiplier":
-                {
-                    if (length > 4 && int.TryParse(command[commandItems[4]], out var value))
-                    {
-                        Configuration.EngineSettings.LMP_MovesDepthMultiplier = value;
-                    }
-                    break;
-                }
             case "history_maxmovevalue":
                 {
                     if (length > 4 && int.TryParse(command[commandItems[4]], out var value))