2 Glaurung, a UCI chess playing engine.
3 Copyright (C) 2004-2008 Tord Romstad
5 Glaurung is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation, either version 3 of the License, or
8 (at your option) any later version.
10 Glaurung is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>.
20 #if !defined(HISTORY_H_INCLUDED)
21 #define HISTORY_H_INCLUDED
36 /// The History class stores statistics about how often different moves have
37 /// been successful or unsuccessful during the current search. These
38 /// statistics are used for reduction and move ordering decisions.
45 void success(Piece p, Move m, Depth d);
46 void failure(Piece p, Move m);
47 int move_ordering_score(Piece p, Move m) const;
48 bool ok_to_prune(Piece p, Move m, Depth d) const;
51 int history[16][64]; // [piece][square]
52 int successCount[16][64];
53 int failureCount[16][64];
58 //// Constants and variables
61 /// HistoryMax controls how often the history counters will be scaled down:
62 /// When the history score for a move gets bigger than HistoryMax, all
63 /// entries in the table are divided by 2. It is difficult to guess what
64 /// the ideal value of this constant is. Scaling down the scores often has
65 /// the effect that parts of the search tree which have been searched
66 /// recently have a bigger importance for move ordering than the moves which
67 /// have been searched a long time ago.
69 /// Note that HistoryMax should probably be changed whenever the constant
70 /// OnePly in depth.h is changed. This is somewhat annoying. Perhaps it
71 /// would be better to scale down the history table at regular intervals?
73 const int HistoryMax = 50000;
76 #endif // !defined(HISTORY_H_INCLUDED)