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Symmetric King Safety: take 2

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Another attempt at retiring current asymmetric
king evaluation and use a much simpler symmetric
one. As a good side effect we can avoid recalculating
eval after a null move.

Tested in no-regression mode and passed

STC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 21580 W: 3752 L: 3632 D: 14196

LTC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 18253 W: 2593 L: 2469 D: 13191

And a LTC regression test against SF DD to
verify we don't have regression against
weaker engines due to some kind of 'contempt'
effect:

ELO: 54.69 +-2.1 (95%) LOS: 100.0%
Total: 40000 W: 11072 L: 4827 D: 24101

bench: 8205159
This commit is contained in:
Lucas Braesch
2014-06-03 20:48:43 +08:00
committed by Marco Costalba
parent 187a9fe5e7
commit adeded29fb
4 changed files with 36 additions and 47 deletions
Download Patch File Download Diff File Expand all files Collapse all files

40
src/evaluate.cpp
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@@ -90,9 +90,9 @@ namespace {
}
// Evaluation weights, indexed by evaluation term
enum { Mobility, PawnStructure, PassedPawns, Space, KingDangerUs, KingDangerThem };
enum { Mobility, PawnStructure, PassedPawns, Space, KingSafety };
const struct Weight { int mg, eg; } Weights[] = {
{289, 344}, {233, 201}, {221, 273}, {46, 0}, {271, 0}, {307, 0}
{289, 344}, {233, 201}, {221, 273}, {46, 0}, {318, 0}
};
typedef Value V;
@@ -150,12 +150,11 @@ namespace {
S(0, 0), S(0, 0), S(56, 70), S(56, 70), S(76, 99), S(86, 118)
};
// Hanging[side to move] contains a bonus for each enemy hanging piece
const Score Hanging[2] = { S(23, 20) , S(35, 45) };
// Hanging contains a bonus for each enemy hanging piece
const Score Hanging = S(23, 20);
#undef S
const Score Tempo = make_score(24, 11);
const Score RookOnPawn = make_score(10, 28);
const Score RookOpenFile = make_score(43, 21);
const Score RookSemiopenFile = make_score(19, 10);
@@ -194,9 +193,9 @@ namespace {
const int BishopCheck = 2;
const int KnightCheck = 3;
// KingDanger[Color][attackUnits] contains the actual king danger weighted
// scores, indexed by color and by a calculated integer number.
Score KingDanger[COLOR_NB][128];
// KingDanger[attackUnits] contains the actual king danger weighted
// scores, indexed by a calculated integer number.
Score KingDanger[128];
// apply_weight() weighs score 'v' by weight 'w' trying to prevent overflow
@@ -426,9 +425,7 @@ namespace {
| ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][ROOK]);
if (b)
attackUnits += QueenContactCheck
* popcount<Max15>(b)
* (Them == pos.side_to_move() ? 2 : 1);
attackUnits += QueenContactCheck * popcount<Max15>(b);
}
// Analyse the enemy's safe rook contact checks. Firstly, find the
@@ -446,9 +443,7 @@ namespace {
| ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][QUEEN]);
if (b)
attackUnits += RookContactCheck
* popcount<Max15>(b)
* (Them == pos.side_to_move() ? 2 : 1);
attackUnits += RookContactCheck * popcount<Max15>(b);
}
// Analyse the enemy's safe distance checks for sliders and knights
@@ -482,7 +477,7 @@ namespace {
// Finally, extract the king danger score from the KingDanger[]
// array and subtract the score from evaluation.
score -= KingDanger[Us == Search::RootColor][attackUnits];
score -= KingDanger[attackUnits];
}
if (Trace)
@@ -521,8 +516,7 @@ namespace {
b = weakEnemies & ~ei.attackedBy[Them][ALL_PIECES];
if (b)
score += more_than_one(b) ? Hanging[Us != pos.side_to_move()] * popcount<Max15>(b)
: Hanging[Us == pos.side_to_move()];
score += more_than_one(b) ? Hanging * popcount<Max15>(b) : Hanging;
}
if (Trace)
@@ -677,9 +671,9 @@ namespace {
Thread* thisThread = pos.this_thread();
// Initialize score by reading the incrementally updated scores included
// in the position object (material + piece square tables) and adding a
// Tempo bonus. Score is computed from the point of view of white.
score = pos.psq_score() + (pos.side_to_move() == WHITE ? Tempo : -Tempo);
// in the position object (material + piece square tables).
// Score is computed from the point of view of white.
score = pos.psq_score();
// Probe the material hash table
ei.mi = Material::probe(pos, thisThread->materialTable, thisThread->endgames);
@@ -831,7 +825,7 @@ namespace {
<< " | MG EG | MG EG | MG EG \n"
<< "---------------------+-------------+-------------+-------------\n";
format_row(ss, "Material, PST, Tempo", PST);
format_row(ss, "Material, PST", PST);
format_row(ss, "Material imbalance", IMBALANCE);
format_row(ss, "Pawns", PAWN);
format_row(ss, "Knights", KNIGHT);
@@ -885,9 +879,7 @@ namespace Eval {
for (int t = 0, i = 1; i < 100; ++i)
{
t = int(std::min(Peak, std::min(0.4 * i * i, t + MaxSlope)));
KingDanger[1][i] = apply_weight(make_score(t, 0), Weights[KingDangerUs]);
KingDanger[0][i] = apply_weight(make_score(t, 0), Weights[KingDangerThem]);
KingDanger[i] = apply_weight(make_score(t, 0), Weights[KingSafety]);
}
}