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Space bonus and number of blocked pawns

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This patch refines the recently introduced interaction between
the space bonus and the number of blocked pawns in a position.

* pawns count as blocked also if their push square is attacked by 2 enemy pawns;
* overall dependence is stronger as well as offset;
* bonus increase is capped at 9 blocked pawns in position;

passed STC
https://tests.stockfishchess.org/tests/view/5e94560663d105aebbab243d
LLR: 2.96 (-2.94,2.94) {-0.50,1.50}
Total: 29500 W: 5842 L: 5603 D: 18055
Ptnml(0-2): 504, 3443, 6677, 3562, 564

passed LTC
https://tests.stockfishchess.org/tests/view/5e95b383c2aaa99f75d1a14d
LLR: 2.95 (-2.94,2.94) {0.25,1.75}
Total: 63504 W: 8329 L: 7974 D: 47201
Ptnml(0-2): 492, 5848, 18720, 6197, 495

closes https://github.com/official-stockfish/Stockfish/pull/2631

bench 4956028
This commit is contained in:
Vizvezdenec 2020-04-15 04:13:50 +03:00 • committed by Joost VandeVondele
parent 5c58f67126
commit ca4e399ea6
2 changed files with 2 additions and 2 deletions
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2
src/evaluate.cpp
View file

@ -695,7 +695,7 @@ namespace {
behind |= shift<Down+Down>(behind);
int bonus = popcount(safe) + popcount(behind & safe & ~attackedBy[Them][ALL_PIECES]);
int weight = pos.count<ALL_PIECES>(Us) - 2 + pe->blocked_count() / 2;
int weight = pos.count<ALL_PIECES>(Us) - 3 + std::min(pe->blocked_count(), 9);
Score score = make_score(bonus * weight * weight / 16, 0);
if (T)

2
src/pawns.cpp
View file

@ -106,7 +106,7 @@ namespace {
phalanx = neighbours & rank_bb(s);
support = neighbours & rank_bb(s - Up);
e->blockedCount[Us] += bool(blocked);
e->blockedCount[Us] += blocked || more_than_one(leverPush);
// A pawn is backward when it is behind all pawns of the same color on
// the adjacent files and cannot safely advance.