Introduce "Zugzwang detection" temporary hack for 1.7.1

Add an UCI option "Zugzwang detection" OFF by default that
enables correct detection of zugzwang.

This is just to let 1.7.1 be 100% compatible with 1.7 and
should be removed after release.

Verified 100% functional equivalent to 1.7

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

diff --git a/src/search.cpp b/src/search.cpp
index 3f8436415358e04840d4f54736446ae82efa7874..0fa78248f8f059e2fea2155e7c48ec81a9a688aa 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -257,7 +257,7 @@ namespace {
   int SearchStartTime, MaxNodes, MaxDepth, MaxSearchTime;
   int AbsoluteMaxSearchTime, ExtraSearchTime, ExactMaxTime;
   bool UseTimeManagement, InfiniteSearch, PonderSearch, StopOnPonderhit;
   int SearchStartTime, MaxNodes, MaxDepth, MaxSearchTime;
   int AbsoluteMaxSearchTime, ExtraSearchTime, ExactMaxTime;
   bool UseTimeManagement, InfiniteSearch, PonderSearch, StopOnPonderhit;

-  bool FirstRootMove, AbortSearch, Quit, AspirationFailLow;
+  bool FirstRootMove, AbortSearch, Quit, AspirationFailLow, ZugDetection;

 
   // Log file
   bool UseLogFile;
 
   // Log file
   bool UseLogFile;


@@ -425,6 +425,7 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move,
   MultiPV                 = get_option_value_int("MultiPV");
   Chess960                = get_option_value_bool("UCI_Chess960");
   UseLogFile              = get_option_value_bool("Use Search Log");
   MultiPV                 = get_option_value_int("MultiPV");
   Chess960                = get_option_value_bool("UCI_Chess960");
   UseLogFile              = get_option_value_bool("Use Search Log");

+  ZugDetection            = get_option_value_bool("Zugzwang detection"); // To be removed after 1.7.1

 
   if (UseLogFile)
       LogFile.open(get_option_value_string("Search Log Filename").c_str(), std::ios::out | std::ios::app);
 
   if (UseLogFile)
       LogFile.open(get_option_value_string("Search Log Filename").c_str(), std::ios::out | std::ios::app);


@@ -2315,7 +2316,7 @@ namespace {
 
     Value v = value_from_tt(tte->value(), ply);
 
 
     Value v = value_from_tt(tte->value(), ply);
 

-    return   (allowNullmove || !(tte->type() & VALUE_TYPE_NULL))
+    return   (allowNullmove || !(tte->type() & VALUE_TYPE_NULL) || !ZugDetection)

 
           && (   tte->depth() >= depth
               || v >= Max(value_mate_in(PLY_MAX), beta)
 
           && (   tte->depth() >= depth
               || v >= Max(value_mate_in(PLY_MAX), beta)

diff --git a/src/ucioption.cpp b/src/ucioption.cpp
index af568a37953799786ce4f15aec954cc18b817e2a..154e141080371612256c68f3b995d147582ebc5b 100644 (file)
--- a/src/ucioption.cpp
+++ b/src/ucioption.cpp
@@ -113,6 +113,9 @@ namespace {
     o["UCI_Chess960"] = Option(false);
     o["UCI_AnalyseMode"] = Option(false);
 
     o["UCI_Chess960"] = Option(false);
     o["UCI_AnalyseMode"] = Option(false);
 

+    // Temporary hack for 1.7.1 to be removed in next release
+    o["Zugzwang detection"] = Option(false);
+

     // Any option should know its name so to be easily printed
     for (Options::iterator it = o.begin(); it != o.end(); ++it)
         it->second.name = it->first;
     // Any option should know its name so to be easily printed
     for (Options::iterator it = o.begin(); it != o.end(); ++it)
         it->second.name = it->first;