Fix a comment in HistoryMax description

[stockfish] / src / history.h

diff --git a/src/history.h b/src/history.h
index b08c8d33ce7034c3a0f9355e5fdaffc621ed9f2c..5c394cc8f17e2ed75f043ba01b0251e607127222 100644 (file)
--- a/src/history.h
+++ b/src/history.h
@@ -34,24 +34,24 @@
 //// Types
 ////
 
 //// Types
 ////
 

-/// The History class stores statistics about how often different moves have
-/// been successful or unsuccessful during the current search.  These
-/// statistics are used for reduction and move ordering decisions.
+/// The History class stores statistics about how often different moves
+/// have been successful or unsuccessful during the current search. These
+/// statistics are used for reduction and move ordering decisions. History
+/// entries are stored according only to moving piece and destination square,
+/// in particular two moves with different origin but same destination and
+/// same piece will be considered identical.

 
 class History {
 
 public:
   History();
   void clear();
 
 class History {
 
 public:
   History();
   void clear();

-  void success(Piece p, Move m, Depth d);
-  void failure(Piece p, Move m);
-  int move_ordering_score(Piece p, Move m) const;
-  bool ok_to_prune(Piece p, Move m, Depth d) const;
+  void success(Piece p, Square to, Depth d);
+  void failure(Piece p, Square to, Depth d);
+  int move_ordering_score(Piece p, Square to) const;

 
 private:
   int history[16][64];  // [piece][square]
 
 private:
   int history[16][64];  // [piece][square]

-  int successCount[16][64];
-  int failureCount[16][64];

 };
 
 
 };
 
 


@@ -61,17 +61,13 @@ private:
 
 /// HistoryMax controls how often the history counters will be scaled down:
 /// When the history score for a move gets bigger than HistoryMax, all
 
 /// HistoryMax controls how often the history counters will be scaled down:
 /// When the history score for a move gets bigger than HistoryMax, all

-/// entries in the table are divided by 2.  It is difficult to guess what
-/// the ideal value of this constant is.  Scaling down the scores often has
+/// entries in the table are divided by 4. It is difficult to guess what
+/// the ideal value of this constant is. Scaling down the scores often has

 /// the effect that parts of the search tree which have been searched
 /// recently have a bigger importance for move ordering than the moves which
 /// have been searched a long time ago.
 /// the effect that parts of the search tree which have been searched
 /// recently have a bigger importance for move ordering than the moves which
 /// have been searched a long time ago.

-///
-/// Note that HistoryMax should probably be changed whenever the constant
-/// OnePly in depth.h is changed.  This is somewhat annoying.  Perhaps it
-/// would be better to scale down the history table at regular intervals?

 
 

-const int HistoryMax = 50000;
+const int HistoryMax = 25000 * OnePly;

 
 
 #endif // !defined(HISTORY_H_INCLUDED)
 
 
 #endif // !defined(HISTORY_H_INCLUDED)