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CuckooChessEngine: Implemented reverse futility pruning.

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This commit is contained in:
Peter Osterlund 2011-12-03 08:12:08 +00:00
parent 62e3ace1ab
commit 15fec82d90
3 changed files with 45 additions and 33 deletions
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2
CuckooChessEngine/src/chess/ComputerPlayer.java
View File

@ -30,7 +30,7 @@ public class ComputerPlayer implements Player {
public static final String engineName;
static {
String name = "CuckooChess 1.13a4";
String name = "CuckooChess 1.13a5";
String m = System.getProperty("sun.arch.data.model");
if ("32".equals(m))
name += " 32-bit";

74
CuckooChessEngine/src/chess/Search.java
View File

@ -535,6 +535,43 @@ public class Search {
return score;
}
// Razoring
if ((Math.abs(alpha) <= MATE0 / 2) && (depth < 4*plyScale) && (beta == alpha + 1)) {
if (evalScore == UNKNOWN_SCORE) {
evalScore = eval.evalPos(pos);
}
final int razorMargin = 250;
if (evalScore < beta - razorMargin) {
q0Eval = evalScore;
int score = quiesce(alpha-razorMargin, beta-razorMargin, ply, 0, inCheck);
if (score <= alpha-razorMargin) {
emptyMove.score = score;
tt.insert(hKey, emptyMove, TTEntry.T_LE, ply, depth, evalScore);
if (log != null) log.logNodeEnd(sti.nodeIdx, score, TTEntry.T_LE, evalScore, hKey);
return score;
}
}
}
// Reverse futility pruning
if (!inCheck && (depth < 5*plyScale) && (posExtend == 0)) {
if ((Math.abs(alpha) <= MATE0 / 2) && (Math.abs(beta) <= MATE0 / 2)) {
int margin;
if (depth <= plyScale) margin = 200;
else if (depth <= 2*plyScale) margin = 400;
else if (depth <= 3*plyScale) margin = 600;
else margin = 800;
if (evalScore == UNKNOWN_SCORE)
evalScore = eval.evalPos(pos);
if (evalScore - margin >= beta) {
emptyMove.score = evalScore - margin;
tt.insert(hKey, emptyMove, TTEntry.T_GE, ply, depth, evalScore);
if (log != null) log.logNodeEnd(sti.nodeIdx, evalScore - margin, TTEntry.T_GE, evalScore, hKey);
return evalScore - margin;
}
}
}
// Try null-move pruning
// FIXME! Try null-move verification in late endgames. See loss in round 21.
sti.currentMove = emptyMove;
@ -593,47 +630,22 @@ public class Search {
}
}
// Razoring
if ((Math.abs(alpha) <= MATE0 / 2) && (depth < 4*plyScale) && (beta == alpha + 1)) {
if (evalScore == UNKNOWN_SCORE) {
evalScore = eval.evalPos(pos);
}
final int razorMargin = 250;
if (evalScore < beta - razorMargin) {
q0Eval = evalScore;
int score = quiesce(alpha-razorMargin, beta-razorMargin, ply, 0, inCheck);
if (score <= alpha-razorMargin) {
emptyMove.score = score;
tt.insert(hKey, emptyMove, TTEntry.T_LE, ply, depth, evalScore);
if (log != null) log.logNodeEnd(sti.nodeIdx, score, TTEntry.T_LE, evalScore, hKey);
return score;
}
}
}
boolean futilityPrune = false;
int futilityScore = alpha;
if (!inCheck && (depth < 5*plyScale) && (posExtend == 0)) {
if ((Math.abs(alpha) <= MATE0 / 2) && (Math.abs(beta) <= MATE0 / 2)) {
int margin;
if (depth <= plyScale) {
margin = 61;
} else if (depth <= 2*plyScale) {
margin = 144;
} else if (depth <= 3*plyScale) {
margin = 268;
} else {
margin = 334;
}
if (evalScore == UNKNOWN_SCORE) {
if (depth <= plyScale) margin = 61;
else if (depth <= 2*plyScale) margin = 144;
else if (depth <= 3*plyScale) margin = 268;
else margin = 334;
if (evalScore == UNKNOWN_SCORE)
evalScore = eval.evalPos(pos);
}
futilityScore = evalScore + margin;
if (futilityScore <= alpha) {
if (futilityScore <= alpha)
futilityPrune = true;
}
}
}
if ((depth > 4*plyScale) && ((hashMove == null) || (hashMove.from == hashMove.to))) {
boolean isPv = beta > alpha + 1;

2
CuckooChessEngine/test/chess/SearchTest.java
View File

@ -83,7 +83,7 @@ public class SearchTest {
sc = new Search(pos, nullHist, 0, tt);
score = sc.negaScout(-mate0, mate0, 0, 3*plyScale, -1, MoveGen.inCheck(pos));
assertTrue(Math.abs(score) < 50); // Stale-mate trap
score2 = idSearch(sc, 5).score;
score2 = idSearch(sc, 9).score;
assertEquals(score, score2);
pos = TextIO.readFEN("8/8/2K5/3QP3/P6P/1q6/8/k7 w - - 31 51");