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Simplification of lazy threshold

Browse source 
Passed STC
http://tests.stockfishchess.org/tests/view/587846c10ebc5915193f74ec
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 217236 W: 39041 L: 39254 D: 138941

Passed LTC
http://tests.stockfishchess.org/tests/view/587e157a0ebc5915193f76e7
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 52396 W: 6883 L: 6804 D: 38709

This submitted version (using if (abs(mg + eg) > 1500) )
seems more logical than the following other green simplification (using if (abs(mg)>1500))
since it can happen than mg_value is > eg_value (about 20% of the time)
and the submitted version seems stronger at LTC

STC
http://tests.stockfishchess.org/tests/view/5879702d0ebc5915193f7585
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 39958 W: 7315 L: 7227 D: 25416

LTC
http://tests.stockfishchess.org/tests/view/5879af3e0ebc5915193f7592
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 204322 W: 26529 L: 26648 D: 151145

bench: 6406285
This commit is contained in:
Alain SAVARD 2017-01-12 22:11:14 -05:00 • committed by Marco Costalba
parent 9eed183489
commit cf4a38e0cb
1 changed files with 8 additions and 20 deletions
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28
src/evaluate.cpp
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@ -217,7 +217,7 @@ namespace {
const int KnightCheck = 924;
// Threshold for lazy evaluation
const Value LazyEval = Value(1500);
const Value LazyThreshold = Value(1500);
// eval_init() initializes king and attack bitboards for a given color
// adding pawn attacks. To be done at the beginning of the evaluation.
@ -792,18 +792,6 @@ namespace {
return sf;
}
Value lazy_eval(Value mg, Value eg) {
if (mg > LazyEval && eg > LazyEval)
return LazyEval + ((mg + eg) / 2 - LazyEval) / 4;
else if (mg < -LazyEval && eg < -LazyEval)
return -LazyEval + ((mg + eg) / 2 + LazyEval) / 4;
return VALUE_ZERO;
}
} // namespace
@ -816,6 +804,7 @@ Value Eval::evaluate(const Position& pos) {
assert(!pos.checkers());
Score mobility[COLOR_NB] = { SCORE_ZERO, SCORE_ZERO };
Value v;
EvalInfo ei;
// Probe the material hash table
@ -835,11 +824,10 @@ Value Eval::evaluate(const Position& pos) {
ei.pe = Pawns::probe(pos);
score += ei.pe->pawns_score();
// We have taken into account all cheap evaluation terms.
// If score exceeds a threshold return a lazy evaluation.
Value lazy = lazy_eval(mg_value(score), eg_value(score));
if (lazy)
return pos.side_to_move() == WHITE ? lazy : -lazy;
// Early exit if score is high
v = (mg_value(score) + eg_value(score)) / 2;
if (abs(v) > LazyThreshold)
return pos.side_to_move() == WHITE ? v : -v;
// Initialize attack and king safety bitboards
eval_init<WHITE>(pos, ei);
@ -874,8 +862,8 @@ Value Eval::evaluate(const Position& pos) {
ScaleFactor sf = evaluate_scale_factor(pos, ei, eg_value(score));
// Interpolate between a middlegame and a (scaled by 'sf') endgame score
Value v = mg_value(score) * int(ei.me->game_phase())
+ eg_value(score) * int(PHASE_MIDGAME - ei.me->game_phase()) * sf / SCALE_FACTOR_NORMAL;
v = mg_value(score) * int(ei.me->game_phase())
+ eg_value(score) * int(PHASE_MIDGAME - ei.me->game_phase()) * sf / SCALE_FACTOR_NORMAL;
v /= int(PHASE_MIDGAME);