Revert LMR reduction based on thinking time

After 500 games at 5+0 on my QUAD (3 days) there
is no difference with old version, so probably it
is a feature that doesn't scale with search depth.

So revert for now, perhaps we should readd under a
different form.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

diff --git a/src/search.cpp b/src/search.cpp
index 692754b11f36bd262764380281e3b847049d7c5e..882fee6f0ee8ec5940c54b2601f085581dd88918 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -215,14 +215,12 @@ namespace {
 
   // Step 14. Reduced search
 
 
   // Step 14. Reduced search
 

-  int ReductionLevel; // 0 = most aggressive reductions, 7 = minimum reductions
-

   // Reduction lookup tables (initialized at startup) and their getter functions
   // Reduction lookup tables (initialized at startup) and their getter functions

-  int8_t    PVReductionMatrix[8][64][64]; // [depth][moveNumber]
-  int8_t NonPVReductionMatrix[8][64][64]; // [depth][moveNumber]
+  int8_t    PVReductionMatrix[64][64]; // [depth][moveNumber]
+  int8_t NonPVReductionMatrix[64][64]; // [depth][moveNumber]

 
 

-  inline Depth    pv_reduction(Depth d, int mn) { return (Depth)    PVReductionMatrix[ReductionLevel][Min(d / 2, 63)][Min(mn, 63)]; }
-  inline Depth nonpv_reduction(Depth d, int mn) { return (Depth) NonPVReductionMatrix[ReductionLevel][Min(d / 2, 63)][Min(mn, 63)]; }
+  inline Depth    pv_reduction(Depth d, int mn) { return (Depth)    PVReductionMatrix[Min(d / 2, 63)][Min(mn, 63)]; }
+  inline Depth nonpv_reduction(Depth d, int mn) { return (Depth) NonPVReductionMatrix[Min(d / 2, 63)][Min(mn, 63)]; }

 
   // Common adjustments
 
 
   // Common adjustments
 


@@ -546,30 +544,20 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move,
   return !Quit;
 }
 
   return !Quit;
 }
 

-// init_reduction_tables() is called by init_search() and initializes
-// the tables used by LMR.
-static void init_reduction_tables(int8_t pvTable[64][64], int8_t nonPvTable[64][64], int pvInhib, int nonPvInhib)
-{
-  double pvBase = 1.001 - log(3.0) * log(16.0) / pvInhib;
-  double nonPvBase = 1.001 - log(3.0) * log(4.0) / nonPvInhib;

 
 

+/// init_search() is called during startup. It initializes various lookup tables
+
+void init_search() {
+
+  // Init our reduction lookup tables

   for (int i = 1; i < 64; i++) // i == depth (OnePly = 1)
       for (int j = 1; j < 64; j++) // j == moveNumber
       {
   for (int i = 1; i < 64; i++) // i == depth (OnePly = 1)
       for (int j = 1; j < 64; j++) // j == moveNumber
       {

-          double    pvRed = pvBase    + log(double(i)) * log(double(j)) / pvInhib;
-          double nonPVRed = nonPvBase + log(double(i)) * log(double(j)) / nonPvInhib;
-
-          pvTable[i][j]    = (int8_t) (   pvRed >= 1.0 ? floor(   pvRed * int(OnePly)) : 0);
-          nonPvTable[i][j] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(OnePly)) : 0);
+          double    pvRed = 0.5 + log(double(i)) * log(double(j)) / 6.0;
+          double nonPVRed = 0.5 + log(double(i)) * log(double(j)) / 3.0;
+          PVReductionMatrix[i][j]    = (int8_t) (   pvRed >= 1.0 ? floor(   pvRed * int(OnePly)) : 0);
+          NonPVReductionMatrix[i][j] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(OnePly)) : 0);

       }
       }

-}
-
-// init_search() is called during startup. It initializes various lookup tables
-void init_search() {
-
-  // Init reduction lookup tables
-  for (int i = 0; i < 8; i++)
-      init_reduction_tables(PVReductionMatrix[i], NonPVReductionMatrix[i], int(4 * pow(1.3, i)), int(2 * pow(1.3, i)));

 
   // Init futility margins array
   for (int i = 0; i < 16; i++) // i == depth (OnePly = 2)
 
   // Init futility margins array
   for (int i = 0; i < 16; i++) // i == depth (OnePly = 2)


@@ -672,19 +660,6 @@ namespace {
             beta  = Min(ValueByIteration[Iteration - 1] + AspirationDelta,  VALUE_INFINITE);
         }
 
             beta  = Min(ValueByIteration[Iteration - 1] + AspirationDelta,  VALUE_INFINITE);
         }
 

-        // Choose optimum reduction level
-        ReductionLevel = 2;
-
-        if (UseTimeManagement)
-        {
-            int level = int(floor(log(float(MaxSearchTime) / current_search_time()) / log(2.0) + 1.0));
-            ReductionLevel = Min(Max(level, 0), 7);
-        }
-        else
-        {
-            //FIXME
-        }
-

         // Search to the current depth, rml is updated and sorted, alpha and beta could change
         value = root_search(p, ss, rml, &alpha, &beta);
 
         // Search to the current depth, rml is updated and sorted, alpha and beta could change
         value = root_search(p, ss, rml, &alpha, &beta);