Safer razoring formula

Add also the possibility to razor at ply one.
It is disable dby default but it seems stronger
against Stockfish itself. It is still not clear if
is stronger against other engines. By now leave
disabled.

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

diff --git a/src/search.cpp b/src/search.cpp
index aaa2f515d7387ce0d7f21dfc28fbd250a029209d..39dcf9768157d4276ccc97fbe50a80bafc2b1c73 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -169,6 +169,7 @@ namespace {
                                Value(0x2A0), Value(0x340), Value(0x3A0) };
 
   // Razoring
+  const bool RazorAtDepthOne = false;
   Depth RazorDepth = 4*OnePly;
   Value RazorMargin = Value(0x300);
 
@@ -416,7 +417,7 @@ void think(const Position &pos, bool infinite, bool ponder, int side_to_move,
   UseFutilityPruning = get_option_value_bool("Futility Pruning (Main Search)");
 
   FutilityMarginQS = value_from_centipawns(get_option_value_int("Futility Margin (Quiescence Search)"));
-  int fmScale = get_option_value_int("Futility Margin (Main Serach)");
+  int fmScale = get_option_value_int("Futility Margin Scale Factor (Main Search)");
   for (int i = 0; i < 6; i++)
       FutilityMargins[i] = (FutilityMargins[i] * fmScale) / 100;
 
@@ -1241,12 +1242,14 @@ namespace {
     else if (   !value_is_mate(beta)
              && approximateEval < beta - RazorMargin
              && depth < RazorDepth
-             && depth > OnePly
+             && (RazorAtDepthOne || depth > OnePly)
              && ttMove == MOVE_NONE
              && !pos.has_pawn_on_7th(pos.side_to_move()))
     {
         Value v = qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
-        if (v < beta - RazorMargin / 2 - int(depth - OnePly) * RazorMargin / 8)
+        if (   (v < beta - RazorMargin - RazorMargin / 4)
+            || (depth <= 2*OnePly && v < beta - RazorMargin)
+            || (depth <=   OnePly && v < beta - RazorMargin / 2))
             return v;
     }
 

diff --git a/src/ucioption.cpp b/src/ucioption.cpp
index e3ebaf1f88830dc9acb90e137600e2533906702d..5c78c00e6a675b372e08d13e1d6cdda7077be77f 100644 (file)
--- a/src/ucioption.cpp
+++ b/src/ucioption.cpp
@@ -124,7 +124,7 @@ namespace {
     o.push_back(Option("Futility Pruning (Main Search)", true));
     o.push_back(Option("Futility Pruning (Quiescence Search)", true));
     o.push_back(Option("Futility Margin (Quiescence Search)", 50, 0, 1000));
-    o.push_back(Option("Futility Margin (Main Serach)", 100, 0, 1000));
+    o.push_back(Option("Futility Margin Scale Factor (Main Search)", 100, 0, 1000));
     o.push_back(Option("Maximum Razoring Depth", 3, 0, 4));
     o.push_back(Option("Razoring Margin", 300, 150, 600));
     o.push_back(Option("LSN filtering", true));