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Ad-hoc shelter rule 

This hacky rule allows to get an about right eval out of this position:
r2qk2r/ppp2p2/2npbn2/2b1p3/2P1P1P1/2NB1PPp/PPNP3K/R1BQ1R2 b kq - 0 13

And, more importantly, passed both short TC:
LLR: 2.95 (-2.94,2.94) [-1.50,4.50]
Total: 6239 W: 1249 L: 1127 D: 3863

And long TC:
LLR: 2.96 (-2.94,2.94) [0.00,6.00]
Total: 38371 W: 6165 L: 5888 D: 26318

bench: 8183238
pull/358/head
Ralph Stößer 2014-01-11 03:00:17 +01:00 committed by Marco Costalba
parent 3d58092ec1
commit 402a7ae151
1 changed files with 9 additions and 2 deletions
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11
src/pawns.cpp
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@ -240,6 +240,7 @@ template<Color Us>
Value Entry::shelter_storm(const Position& pos, Square ksq) {
const Color Them = (Us == WHITE ? BLACK : WHITE);
static const Bitboard MiddleEdges = (FileABB | FileHBB) & (Rank2BB | Rank3BB);
Value safety = MaxSafetyBonus;
Bitboard b = pos.pieces(PAWN) & (in_front_bb(Us, rank_of(ksq)) | rank_bb(ksq));
@ -252,11 +253,17 @@ Value Entry::shelter_storm(const Position& pos, Square ksq) {
{
b = ourPawns & file_bb(f);
rkUs = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1;
safety -= ShelterWeakness[rkUs];
b = theirPawns & file_bb(f);
rkThem = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1;
safety -= StormDanger[rkUs == RANK_1 ? 0 : rkThem == rkUs + 1 ? 2 : 1][rkThem];
if ( (MiddleEdges & (f | rkThem))
&& file_of(ksq) == f
&& relative_rank(Us, ksq) == rkThem - 1)
safety += Value(200);
else
safety -= ShelterWeakness[rkUs]
+ StormDanger[rkUs == RANK_1 ? 0 : rkThem == rkUs + 1 ? 2 : 1][rkThem];
}
return safety;