Use (strict) greater-than-operator for 'improving'

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index ec9c6b1d0507c77734f92fe8d3a7d067de2334d4..21df156c7ce979d040049234e1d5c1bca1bf665d 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -564,6 +564,7 @@ void Thread::search() {
                   Threads.stop = true;
           }
           else if (   Threads.increaseDepth
+                   && !mainThread->ponder
                    && Time.elapsed() > Time.optimum() * fallingEval * reduction * bestMoveInstability * 0.6)
                    Threads.increaseDepth = false;
           else
@@ -624,7 +625,7 @@ namespace {
     Move ttMove, move, excludedMove, bestMove;
     Depth extension, newDepth;
     Value bestValue, value, ttValue, eval, maxValue;
-    bool ttHit, ttPv, inCheck, givesCheck, improving, didLMR, priorCapture;
+    bool ttHit, ttPv, inCheck, givesCheck, improving , didLMR, priorCapture;
     bool captureOrPromotion, doFullDepthSearch, moveCountPruning, ttCapture, singularLMR;
     Piece movedPiece;
     int moveCount, captureCount, quietCount;
@@ -824,8 +825,9 @@ namespace {
         &&  eval <= alpha - RazorMargin)
         return qsearch<NT>(pos, ss, alpha, beta);
 
-    improving =  (ss-2)->staticEval == VALUE_NONE ? (ss->staticEval >= (ss-4)->staticEval
-              || (ss-4)->staticEval == VALUE_NONE) : ss->staticEval >= (ss-2)->staticEval;
+    // (~13 Elo)
+    improving =  (ss-2)->staticEval == VALUE_NONE ? (ss->staticEval > (ss-4)->staticEval
+              || (ss-4)->staticEval == VALUE_NONE) : ss->staticEval > (ss-2)->staticEval;
 
     // Step 8. Futility pruning: child node (~50 Elo)
     if (   !PvNode
@@ -1015,11 +1017,11 @@ moves_loop: // When in check, search starts from here
               // Futility pruning: parent node (~5 Elo)
               if (   lmrDepth < 6
                   && !inCheck
-                  && ss->staticEval + 255 + 182 * lmrDepth <= alpha
+                  && ss->staticEval + 235 + 172 * lmrDepth <= alpha
                   &&  thisThread->mainHistory[us][from_to(move)]
                     + (*contHist[0])[movedPiece][to_sq(move)]
                     + (*contHist[1])[movedPiece][to_sq(move)]
-                    + (*contHist[3])[movedPiece][to_sq(move)] < 30000)
+                    + (*contHist[3])[movedPiece][to_sq(move)] < 25000)
                   continue;
 
               // Prune moves with negative SEE (~20 Elo)
@@ -1114,7 +1116,7 @@ moves_loop: // When in check, search starts from here
       // Step 16. Reduced depth search (LMR, ~200 Elo). If the move fails high it will be
       // re-searched at full depth.
       if (    depth >= 3
-          &&  moveCount > 1 + 2 * rootNode
+          &&  moveCount > 1 + rootNode + (rootNode && bestValue < alpha)
           && (!rootNode || thisThread->best_move_count(move) == 0)
           && (  !captureOrPromotion
               || moveCountPruning
@@ -1185,6 +1187,10 @@ moves_loop: // When in check, search starts from here
               r -= ss->statScore / 16384;
           }
 
+          // Increase reduction for captures/promotions if late move and at low depth
+          else if (depth < 8 && moveCount > 2)
+              r++;
+
           Depth d = clamp(newDepth - r, 1, newDepth);
 
           value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);