if (nullValue >= VALUE_MATE_IN_MAX_PLY)
nullValue = beta;
- if (depth < 6 * ONE_PLY)
+ if (depth < 12 * ONE_PLY)
return nullValue;
// Do verification search at high depths
ss->ply = (ss-1)->ply + 1;
// Check for an instant draw or maximum ply reached
- if (pos.is_draw<true>() || ss->ply > MAX_PLY)
+ if (pos.is_draw<false>() || ss->ply > MAX_PLY)
return DrawValue[pos.side_to_move()];
// Decide whether or not to include checks, this fixes also the type of
continue;
}
- // Prune moves with negative or equal SEE
+ // Prune moves with negative or equal SEE and also moves with positive
+ // SEE where capturing piece loses a tempo and SEE < beta - futilityBase.
if ( futilityBase < beta
&& depth < DEPTH_ZERO
- && pos.see(move) <= 0)
+ && pos.see(move, beta - futilityBase) <= 0)
{
bestValue = std::max(bestValue, futilityBase);
continue;