Combo of several promising parameter tweaks

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 28fbf25418cad775b3eb549eb8d0c49440576955..0f27564a1053513b392b117a34303abe88db3a12 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -66,7 +66,7 @@ namespace {
   constexpr int SkipPhase[] = { 0, 1, 0, 1, 2, 3, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5, 6, 7 };
 
   // Razor and futility margins
-  constexpr int RazorMargin[] = {0, 590, 604};
+  constexpr int RazorMargin = 600;
   Value futility_margin(Depth d, bool improving) {
     return Value((175 - 50 * improving) * d / ONE_PLY);
   }
@@ -82,7 +82,7 @@ namespace {
   // History and stats update bonus, based on depth
   int stat_bonus(Depth depth) {
     int d = depth / ONE_PLY;
-    return d > 17 ? 0 : 33 * d * d + 66 * d - 66;
+    return d > 17 ? 0 : 29 * d * d + 138 * d - 134;
   }
 
   // Skill structure is used to implement strength limit
@@ -730,15 +730,9 @@ namespace {
     }
 
     // Step 7. Razoring (~2 Elo)
-    if (  !PvNode
-        && depth < 3 * ONE_PLY
-        && eval <= alpha - RazorMargin[depth / ONE_PLY])
-    {
-        Value ralpha = alpha - (depth >= 2 * ONE_PLY) * RazorMargin[depth / ONE_PLY];
-        Value v = qsearch<NonPV>(pos, ss, ralpha, ralpha+1);
-        if (depth < 2 * ONE_PLY || v <= ralpha)
-            return v;
-    }
+    if (   depth < 2 * ONE_PLY
+        && eval <= alpha - RazorMargin)
+        return qsearch<NT>(pos, ss, alpha, beta);
 
     improving =   ss->staticEval >= (ss-2)->staticEval
                || (ss-2)->staticEval == VALUE_NONE;
@@ -753,7 +747,7 @@ namespace {
     // Step 9. Null move search with verification search (~40 Elo)
     if (   !PvNode
         && (ss-1)->currentMove != MOVE_NULL
-        && (ss-1)->statScore < 22500
+        && (ss-1)->statScore < 23200
         &&  eval >= beta
         &&  ss->staticEval >= beta - 36 * depth / ONE_PLY + 225
         && !excludedMove
@@ -998,18 +992,12 @@ moves_loop: // When in check, search starts from here
       {
           Depth r = reduction<PvNode>(improving, depth, moveCount);
 
-          if (captureOrPromotion) // (~5 Elo)
-          {
-              // Decrease reduction by comparing opponent's stat score
-              if ((ss-1)->statScore < 0)
-                  r -= ONE_PLY;
-          }
-          else
-          {
-              // Decrease reduction if opponent's move count is high (~5 Elo)
-              if ((ss-1)->moveCount > 15)
-                  r -= ONE_PLY;
+          // Decrease reduction if opponent's move count is high (~10 Elo)
+          if ((ss-1)->moveCount > 15)
+              r -= ONE_PLY;
 
+          if (!captureOrPromotion)
+          {
               // Decrease reduction for exact PV nodes (~0 Elo)
               if (pvExact)
                   r -= ONE_PLY;