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Simplify extensions 

Unify extensions between PV and not PV nodes
and remove all but check extensions.

This is a simplification so tested at fixed number
of games where proved to not regress.

About 45k games at 15+0.05
ELO: 1.23 +-2.0 (95%) LOS: 88.5%
Total: 45643 W: 9107 L: 8946 D: 27590

About 45k games at 60+0.05
ELO: 1.07 +-1.8 (95%) LOS: 87.8%
Total: 46786 W: 7728 L: 7584 D: 31474

bench: 3172206
sf_dd_base
Lucas Braesch 2013-09-26 18:25:27 +08:00 committed by Marco Costalba
parent 8d1c1074d5
commit bc6faf633e
1 changed files with 2 additions and 5 deletions
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7
src/search.cpp
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@ -829,13 +829,10 @@ moves_loop: // When in check and at SpNode search starts from here
|| pos.is_passed_pawn_push(move)
|| type_of(move) == CASTLE;
// Step 12. Extend checks and, in PV nodes, also dangerous moves
if (PvNode && dangerous)
// Step 12. Extend checks
if (givesCheck && pos.see_sign(move) >= 0)
ext = ONE_PLY;
else if (givesCheck && pos.see_sign(move) >= 0)
ext = inCheck || ss->staticEval <= alpha ? ONE_PLY : ONE_PLY / 2;
// Singular extension search. If all moves but one fail low on a search of
// (alpha-s, beta-s), and just one fails high on (alpha, beta), then that move
// is singular and should be extended. To verify this we do a reduced search