Simple razoring: depth 1 only, no distinction between PV / NonPV

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 990c4123e6a91659ed0ab94baaca28a01ad8037d..bd5eb2608cfa6714879d2cfd33b0e87ef5bc8a7c 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);
   }
@@ -250,26 +250,29 @@ void MainThread::search() {
       Value minScore = this->rootMoves[0].score;
 
       // Find out minimum score and reset votes for moves which can be voted
-      for (Thread* th: Threads){
+      for (Thread* th: Threads)
+      {
           minScore = std::min(minScore, th->rootMoves[0].score);
           votes[th->rootMoves[0].pv[0]] = 0;
       }
 
       // Vote according to score and depth
       for (Thread* th : Threads)
-          votes[th->rootMoves[0].pv[0]] +=  int(th->rootMoves[0].score - minScore)  + int(th->completedDepth);
+          votes[th->rootMoves[0].pv[0]] +=  int(th->rootMoves[0].score - minScore)  
+                                          + int(th->completedDepth);
 
       // Select best thread
       int bestVote = votes[this->rootMoves[0].pv[0]];
-      for (Thread* th : Threads){
-          if (votes[th->rootMoves[0].pv[0]] > bestVote){
-            bestVote = votes[th->rootMoves[0].pv[0]];
-            bestThread = th;
+      for (Thread* th : Threads)
+      {
+          if (votes[th->rootMoves[0].pv[0]] > bestVote)
+          {
+              bestVote = votes[th->rootMoves[0].pv[0]];
+              bestThread = th;
           }
       }
   }
 
-
   previousScore = bestThread->rootMoves[0].score;
 
   // Send again PV info if we have a new best thread
@@ -727,15 +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;
@@ -995,18 +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;