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CuckooChess: Don't use LMP when alpha or beta is a mate score.

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This commit is contained in:
Peter Osterlund 2012-03-04 19:00:09 +00:00
parent 43e0f00175
commit 4f4c1c75e7
5 changed files with 26 additions and 12 deletions
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1
CuckooChessEngine/src/chess/Evaluate.java
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@ -756,6 +756,7 @@ public class Evaluate {
}
private int threatBonus(Position pos) {
// FIXME!! Try higher weight for attacks on more valuable pieces.
int score = 0;
// Sum values for all black pieces under attack

2
CuckooChessEngine/src/chess/Player.java
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@ -53,7 +53,7 @@ public interface Player {
/**
* Inform player that the transposition table should be cleared.
* Of coarse, a human player has a hard time implementing this.
* Of course, a human player has a hard time implementing this.
*/
public void clearTT();
}

2
CuckooChessEngine/src/chess/Search.java
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@ -734,6 +734,7 @@ public class Search {
boolean givesCheck = MoveGen.givesCheck(pos, m);
boolean doFutility = false;
if (mayReduce && haveLegalMoves && !givesCheck && !passedPawnPush(pos, m)) {
if ((Math.abs(alpha) <= MATE0 / 2) && (Math.abs(beta) <= MATE0 / 2)) {
int moveCountLimit;
if (depth <= plyScale) moveCountLimit = 3;
else if (depth <= 2 * plyScale) moveCountLimit = 6;
@ -742,6 +743,7 @@ public class Search {
else moveCountLimit = 256;
if (mi >= moveCountLimit)
continue; // Late move pruning
}
if (futilityPrune)
doFutility = true;
}

2
CuckooChessEngine/src/chess/TextIO.java
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@ -290,7 +290,7 @@ public class TextIO {
ret.append("O-O-O");
}
} else if (move.from == bKingOrigPos && pos.getPiece(bKingOrigPos) == Piece.BKING) {
// Check white castle
// Check black castle
if (move.to == Position.getSquare(6, 7)) {
ret.append("O-O");
} else if (move.to == Position.getSquare(2, 7)) {

13
CuckooChessEngine/test/chess/SearchTest.java
View File

@ -205,6 +205,17 @@ public class SearchTest {
assertEquals(TextIO.stringToMove(pos, "Kb1"), new Move(bestM));
}
/**
* Late move pruning must not be used in mate search.
*/
@Test
public void testLMP() throws ChessParseError {
Position pos = TextIO.readFEN("2r2rk1/6p1/p3pq1p/1p1b1p2/3P1n2/PP3N2/3N1PPP/1Q2RR1K b"); // WAC 174
Search sc = new Search(pos, nullHist, 0, tt);
Move bestM = idSearch(sc, 2);
assertTrue(bestM.score < Search.MATE0 / 2);
}
@Test
public void testCheckEvasion() throws ChessParseError {
System.out.println("check evasion");
@ -234,7 +245,7 @@ public class SearchTest {
System.out.println("kqkrNullMove");
Position pos = TextIO.readFEN("7K/6R1/5k2/3q4/8/8/8/8 b - - 0 1");
Search sc = new Search(pos, nullHist, 0, tt);
Move bestM = idSearch(sc, 9);
Move bestM = idSearch(sc, 10);
assertEquals(Search.MATE0-18, bestM.score);
}