From: Marco Costalba <mcostalba@gmail.com>
Date: Tue, 28 Apr 2009 06:51:11 +0000 (+0200)
Subject: Merge Joona's razoring tweaks
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=f1d982e2c07372627394b83cf24f48e77a34145b;hp=fbca16da570756f5220b229845e566bd05aa3ce8

Merge Joona's razoring tweaks
After proof testing on 3 different engines these
are the results:

Stockfish - Toga II 1.4.1SE +130 -132 =132 49.75%
Stockfish - Deep Sieng 3.0  +145 -110 =150 54.45%
Stockfish - HIARCS 12 MP    +94  -149 =150 43.00%

So it seems no regressions occurs, although also no
improvment. But anyhow this patch increases Stockfish
strenght against itself, so merge it.

Note that this patch not only adds back razoring at depth
one, but also increases razor depth limit from 3 to 4
because hard coded depth 4 limit is no more overwritten
by UCI parameter that otherwise defaults to 3.
---

diff --git a/src/search.cpp b/src/search.cpp
index 0ac38d05..3ad5423d 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -180,14 +180,20 @@ namespace {
 
   // Margins for futility pruning in the quiescence search, and at frontier
   // and near frontier nodes
-  Value FutilityMarginQS;
-  Value FutilityMargins[6] = { Value(0x100), Value(0x200), Value(0x250),
-                               Value(0x2A0), Value(0x340), Value(0x3A0) };
+  const Value FutilityMarginQS = Value(0x80);
 
-  // Razoring
-  const bool RazorAtDepthOne = false;
-  Depth RazorDepth;
-  Value RazorMargin;
+   // Remaining depth:                  1 ply         1.5 ply       2 ply         2.5 ply       3 ply         3.5 ply
+   const Value FutilityMargins[12] = { Value(0x100), Value(0x120), Value(0x200), Value(0x220), Value(0x250), Value(0x270),
+  //                                   4 ply         4.5 ply       5 ply         5.5 ply       6 ply         6.5 ply
+                                      Value(0x2A0), Value(0x2C0), Value(0x340), Value(0x360), Value(0x3A0), Value(0x3C0) };
+   // Razoring
+   const Depth RazorDepth = 4*OnePly;
+
+  // Remaining depth:                 1 ply         1.5 ply       2 ply         2.5 ply       3 ply         3.5 ply
+  const Value RazorMargins[6]     = { Value(0x180), Value(0x300), Value(0x300), Value(0x3C0), Value(0x3C0), Value(0x3C0) };
+
+  // Remaining depth:                 1 ply         1.5 ply       2 ply         2.5 ply       3 ply         3.5 ply
+   const Value RazorApprMargins[6] = { Value(0x520), Value(0x300), Value(0x300), Value(0x300), Value(0x300), Value(0x300) };
 
   // Last seconds noise filtering (LSN)
   bool UseLSNFiltering;
@@ -436,14 +442,6 @@ void think(const Position &pos, bool infinite, bool ponder, int side_to_move,
   UseQSearchFutilityPruning = get_option_value_bool("Futility Pruning (Quiescence Search)");
   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 Scale Factor (Main Search)");
-  for (int i = 0; i < 6; i++)
-      FutilityMargins[i] = (FutilityMargins[i] * fmScale) / 100;
-
-  RazorDepth = (get_option_value_int("Maximum Razoring Depth") + 1) * OnePly;
-  RazorMargin = value_from_centipawns(get_option_value_int("Razoring Margin"));
-
   UseLSNFiltering = get_option_value_bool("LSN filtering");
   LSNTime = get_option_value_int("LSN Time Margin (sec)") * 1000;
   LSNValue = value_from_centipawns(get_option_value_int("LSN Value Margin"));
@@ -1309,17 +1307,14 @@ namespace {
     }
     // Null move search not allowed, try razoring
     else if (   !value_is_mate(beta)
-             && approximateEval < beta - RazorMargin
              && depth < RazorDepth
-             && (RazorAtDepthOne || depth > OnePly)
+             && approximateEval < beta - RazorApprMargins[int(depth) - 2]
              && 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 - RazorMargin / 4)
-            || (depth <= 2*OnePly && v < beta - RazorMargin)
-            || (depth <=   OnePly && v < beta - RazorMargin / 2))
-            return v;
+        if (v < beta - RazorMargins[int(depth) - 2])
+          return v;
     }
 
     // Go with internal iterative deepening if we don't have a TT move
@@ -1378,8 +1373,7 @@ namespace {
           {
               if (futilityValue == VALUE_NONE)
                   futilityValue =  evaluate(pos, ei, threadID)
-                                 + FutilityMargins[int(depth)/2 - 1]
-                                 + 32 * (depth & 1);
+                                 + FutilityMargins[int(depth) - 2];
 
               if (futilityValue < beta)
               {
diff --git a/src/ucioption.cpp b/src/ucioption.cpp
index 006c4c56..442ca924 100644
--- a/src/ucioption.cpp
+++ b/src/ucioption.cpp
@@ -127,10 +127,6 @@ namespace {
     o["Threat Depth"] = Option(5, 0, 100);
     o["Futility Pruning (Main Search)"] = Option(true);
     o["Futility Pruning (Quiescence Search)"] = Option(true);
-    o["Futility Margin (Quiescence Search)"] = Option(50, 0, 1000);
-    o["Futility Margin Scale Factor (Main Search)"] = Option(100, 0, 1000);
-    o["Maximum Razoring Depth"] = Option(3, 0, 4);
-    o["Razoring Margin"] = Option(300, 150, 600);
     o["LSN filtering"] = Option(true);
     o["LSN Time Margin (sec)"] = Option(4, 1, 10);
     o["LSN Value Margin"] = Option(200, 100, 600);