Simplify Tweak late move reductions at root.

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 21df156c7ce979d040049234e1d5c1bca1bf665d..9562bf8640d4e8b04772d0e915281107e6218f97 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -625,7 +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;
@@ -825,7 +825,6 @@ namespace {
         &&  eval <= alpha - RazorMargin)
         return qsearch<NT>(pos, ss, alpha, beta);
 
-    // (~13 Elo)
     improving =  (ss-2)->staticEval == VALUE_NONE ? (ss->staticEval > (ss-4)->staticEval
               || (ss-4)->staticEval == VALUE_NONE) : ss->staticEval > (ss-2)->staticEval;
 
@@ -842,7 +841,7 @@ namespace {
         && (ss-1)->statScore < 23397
         &&  eval >= beta
         &&  eval >= ss->staticEval
-        &&  ss->staticEval >= beta - 32 * depth + 292 - improving * 30
+        &&  ss->staticEval >= beta - 32 * depth - 30 * improving + 120 * ttPv + 292
         && !excludedMove
         &&  pos.non_pawn_material(us)
         && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor))
@@ -1029,7 +1028,7 @@ moves_loop: // When in check, search starts from here
                   continue;
           }
           else if (!pos.see_ge(move, Value(-194) * depth)) // (~25 Elo)
-                  continue;
+              continue;
       }
 
       // Step 14. Extensions (~75 Elo)
@@ -1116,7 +1115,7 @@ 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 + rootNode + (rootNode && bestValue < alpha)
+          &&  moveCount > 1 + 2 * rootNode
           && (!rootNode || thisThread->best_move_count(move) == 0)
           && (  !captureOrPromotion
               || moveCountPruning
@@ -1161,7 +1160,7 @@ moves_loop: // When in check, search starts from here
               // hence break make_move(). (~2 Elo)
               else if (    type_of(move) == NORMAL
                        && !pos.see_ge(reverse_move(move)))
-                  r -= 2;
+                  r -= 2 + ttPv;
 
               ss->statScore =  thisThread->mainHistory[us][from_to(move)]
                              + (*contHist[0])[movedPiece][to_sq(move)]