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Futility pruning simplification

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1/ eval margin and gains removed:
16bit are now free on TT entries, due to the removal of eval margin. may be useful
in the future :) gains removed: use instead by Value(128). search() and qsearch()
are now consistent in this regard.

2/ futility_margin()
linear formula instead of complex (log(depth), movecount) formula.

3/ unify pre & post futility pruning
pre futility pruning used depth < 7 plies, while post futility pruning used
depth < 4 plies. Now it's always depth < 7.

Tested with fixed number of games both at short TC:
ELO: 0.82 +-2.1 (95%) LOS: 77.3%
Total: 40000 W: 7939 L: 7845 D: 24216

And long TC
ELO: 0.59 +-2.0 (95%) LOS: 71.9%
Total: 40000 W: 6876 L: 6808 D: 26316

bench 7243575
This commit is contained in:
Lucas Braesch
2013-11-08 18:42:22 +08:00
committed by Marco Costalba
parent 343544f3f7
commit eed508b444
7 changed files with 59 additions and 116 deletions
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4
src/tt.cpp
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@@ -89,7 +89,7 @@ const TTEntry* TranspositionTable::probe(const Key key) const {
/// more valuable than a TTEntry t2 if t1 is from the current search and t2 is from
/// a previous search, or if the depth of t1 is bigger than the depth of t2.
void TranspositionTable::store(const Key key, Value v, Bound b, Depth d, Move m, Value statV, Value evalM) {
void TranspositionTable::store(const Key key, Value v, Bound b, Depth d, Move m, Value statV) {
int c1, c2, c3;
TTEntry *tte, *replace;
@@ -117,5 +117,5 @@ void TranspositionTable::store(const Key key, Value v, Bound b, Depth d, Move m,
replace = tte;
}
replace->save(key32, v, b, d, m, generation, statV, evalM);
replace->save(key32, v, b, d, m, generation, statV);
}