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Count passed pawns in asymmetry measure

Browse source 
The previous asymmetry measure of the pawn structure only used to
consider the number of pawns on semi-opened files in the postions.
With this patch we also increase the measure by the number of passed
pawns for both players.

STC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 13146 W: 3038 L: 2840 D: 7268
http://tests.stockfishchess.org/tests/view/5a91dd0c0ebc590297cc877e

LTC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 27776 W: 4771 L: 4536 D: 18469
http://tests.stockfishchess.org/tests/view/5a91fdd50ebc590297cc879b

How to continue from there: Stockfish will now evaluate more positions
with passed pawns, so tuning the passed pawns values may bring Elo.
The patch also has consequences on the initiative term.

Bench: 5302866
This commit is contained in:
Stéphane Nicolet 2018-02-25 13:12:09 +01:00
parent 8dd6875240
commit 2e21aba8d9
1 changed files with 6 additions and 2 deletions
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6
src/pawns.cpp
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@ -164,6 +164,9 @@ namespace {
e->passedPawns[Us] |= s;
}
if (e->passedPawns[Us] & s)
e->asymmetry++;
// Score this pawn
if (supported | phalanx)
score += Connected[opposed][bool(phalanx)][popcount(supported)][relative_rank(Us, s)];
@ -220,9 +223,10 @@ Entry* probe(const Position& pos) {
return e;
e->key = key;
e->asymmetry = 0;
e->scores[WHITE] = evaluate<WHITE>(pos, e);
e->scores[BLACK] = evaluate<BLACK>(pos, e);
e->asymmetry = popcount(e->semiopenFiles[WHITE] ^ e->semiopenFiles[BLACK]);
e->asymmetry += popcount(e->semiopenFiles[WHITE] ^ e->semiopenFiles[BLACK]);
e->openFiles = popcount(e->semiopenFiles[WHITE] & e->semiopenFiles[BLACK]);
return e;