return do_see<false>(m, 0);
}
+/// Position::see_asymm() takes tempi into account.
+/// If the side who initiated the capturing sequence does the last capture,
+/// he loses a tempo. In this case if the result is below asymmThreshold
+/// the capturing sequence is considered bad.
+
int Position::see_asymm(Move m, int asymmThreshold) const
{
return do_see<true>(m, asymmThreshold);
} while (stmAttackers);
- // FIXME: Document
+ // If we are doing asymmetric SEE evaluation and the same side does the first
+ // and the last capture, he loses a tempo and gain must be at least worth "asymmThreshold".
+ // If not, we replace the score with a very low value, before negamaxing.
if (Asymmetric)
{
for (int i = 0; i < slIndex ; i += 2)
int see(Move m) const;
int see_sign(Move m) const;
int see_asymm(Move m, int asymmThreshold) const;
- template <bool Asymmetric> int do_see(Move m, int asymmThreshold) const; //FIXME: private!!
// Accessing hash keys
Key key() const;
// Helper functions
void do_castle(Square kfrom, Square kto, Square rfrom, Square rto);
+ template<bool Asymmetric> int do_see(Move m, int asymmThreshold) const;
template<bool FindPinned> Bitboard hidden_checkers() const;
// Computing hash keys from scratch (for initialization and debugging)
continue;
}
- // Prune moves with negative or equal SEE
+ // Prune moves with negative or equal SEE.
+ // Also prune moves with positive SEE where capturing loses a tempo and SEE < beta - futilityBase.
if ( futilityBase < beta
&& depth < DEPTH_ZERO
&& pos.see_asymm(move, beta - futilityBase) <= 0)