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Tweak initiative formula

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Give more weight to the pawns number and
the vertical king distance in evaluate_initiative()

Passed STC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 26729 W: 5067 L: 4825 D: 16837

and LTC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 60480 W: 8338 L: 8016 D: 44126

Bench: 8295162

Resolves #594
This commit is contained in:
snicolet
2016-03-02 00:00:41 +00:00
committed by Joona Kiiski
parent c13052f344
commit c1be0c68c7
1 changed files with 3 additions and 2 deletions
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5
src/evaluate.cpp
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@@ -679,11 +679,12 @@ namespace {
// status of the players. // status of the players.
Score evaluate_initiative(const Position& pos, int asymmetry, Value eg) { Score evaluate_initiative(const Position& pos, int asymmetry, Value eg) {
int kingDistance = distance<File>(pos.square<KING>(WHITE), pos.square<KING>(BLACK)); int kingDistance = distance<File>(pos.square<KING>(WHITE), pos.square<KING>(BLACK))
- distance<Rank>(pos.square<KING>(WHITE), pos.square<KING>(BLACK));
int pawns = pos.count<PAWN>(WHITE) + pos.count<PAWN>(BLACK); int pawns = pos.count<PAWN>(WHITE) + pos.count<PAWN>(BLACK);
// Compute the initiative bonus for the attacking side // Compute the initiative bonus for the attacking side
int initiative = 8 * (pawns + asymmetry + kingDistance - 15); int initiative = 8 * (asymmetry + kingDistance) + 12 * pawns - 120;
// Now apply the bonus: note that we find the attacking side by extracting // Now apply the bonus: note that we find the attacking side by extracting
// the sign of the endgame value, and that we carefully cap the bonus so // the sign of the endgame value, and that we carefully cap the bonus so