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Refine rook penalty on closed files 

+-----------------+
| . . . . . . . . | All files are closed. Some files are
| . . . . . o o . | more valuable for rooks, because
| . . . . o . . o | they might open in the future.
| . . . o x . . x |
| o . o x . x x . |
| x o x . . . . . | x  our pawns
| . x . . . . . . | o  their pawns
| . . . . . . . . | ^  rooks are scored higher on these files
+-----------------+
            ^ ^

Files containing none of our own pawns are open or half-open (otherwise
they are closed). Rooks on (half-)open files recieve a bonus for the
future potential to act along all ranks.

This commit refines the (relative) penalty of rooks on closed files.
Files that contain one of our blocked pawns are considered less likely
to open in the future; rooks on these files are now penalized stronger.

This bonus does not generally correlate with mobility. If the condition
is sufficiently refined in the future, it may be beneficial to adjust or
override mobility scores in some cases.

LTC
LLR: 2.94 (-2.94,2.94) {0.25,1.25}
Total: 494384 W: 71565 L: 70231 D: 352588
Ptnml(0-2): 3907, 48050, 142118, 49036, 4081
https://tests.stockfishchess.org/tests/view/5fb9312e67cbf42301d6afb9

LTC (non-regression w/ book noob_3moves.epd)
LLR: 2.95 (-2.94,2.94) {-0.75,0.25}
Total: 208520 W: 27044 L: 26937 D: 154539
Ptnml(0-2): 1557, 19850, 61391, 19853, 1609
https://tests.stockfishchess.org/tests/view/5fc01ced67cbf42301d6b3df

STC
LLR: 2.94 (-2.94,2.94) {-0.25,1.25}
Total: 98392 W: 20269 L: 19868 D: 58255
Ptnml(0-2): 1804, 11297, 22589, 11706, 1800
https://tests.stockfishchess.org/tests/view/5fb7f88a67cbf42301d6af10

closes https://github.com/official-stockfish/Stockfish/pull/3242

Bench: 3682630
pull/3253/head
Lolligerhans 2020-11-20 18:09:41 +01:00 committed by Joost VandeVondele
parent 9b7983a452
commit d6d6972a66
1 changed files with 22 additions and 11 deletions
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33
src/evaluate.cpp
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@ -240,9 +240,8 @@ namespace {
S(0, 0), S(9, 28), S(15, 31), S(17, 39), S(64, 70), S(171, 177), S(277, 260)
};
// RookOnFile[semiopen/open] contains bonuses for each rook when there is
// no (friendly) pawn on the rook file.
constexpr Score RookOnFile[] = { S(19, 7), S(48, 27) };
constexpr Score RookOnClosedFile = S(10, 5);
constexpr Score RookOnOpenFile[] = { S(19, 7), S(48, 27) };
// ThreatByMinor/ByRook[attacked PieceType] contains bonuses according to
// which piece type attacks which one. Attacks on lesser pieces which are
@ -485,16 +484,28 @@ namespace {
if (Pt == ROOK)
{
// Bonus for rook on an open or semi-open file
// Bonuses for rook on a (semi-)open or closed file
if (pos.is_on_semiopen_file(Us, s))
score += RookOnFile[pos.is_on_semiopen_file(Them, s)];
// Penalty when trapped by the king, even more if the king cannot castle
else if (mob <= 3)
{
File kf = file_of(pos.square<KING>(Us));
if ((kf < FILE_E) == (file_of(s) < kf))
score -= TrappedRook * (1 + !pos.castling_rights(Us));
score += RookOnOpenFile[pos.is_on_semiopen_file(Them, s)];
}
else
{
// If our pawn on this file is blocked, increase penalty
if ( pos.pieces(Us, PAWN)
& shift<Down>(pos.pieces())
& file_bb(s))
{
score -= RookOnClosedFile;
}
// Penalty when trapped by the king, even more if the king cannot castle
if (mob <= 3)
{
File kf = file_of(pos.square<KING>(Us));
if ((kf < FILE_E) == (file_of(s) < kf))
score -= TrappedRook * (1 + !pos.castling_rights(Us));
}
}
}