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fix perpetual check #83

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fix perpetual check #83

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580aefa
fix perpetual check
KazApps Mar 22, 2025
36b4bf3
version
KazApps Mar 22, 2025
6e0e783
fix bug
KazApps Jun 20, 2025
9a89e3f
Merge branch 'main' into fix/perpetual-check
KazApps Jun 20, 2025
c5e26f5
version
KazApps Jun 20, 2025
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4 changes: 2 additions & 2 deletions src/datagen/datagen.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -85,7 +85,7 @@ namespace stoat::datagen {
const auto sennichite = newPos.testSennichite(false, keyHistory);
keyHistory.pop_back();

if (sennichite != SennichiteStatus::kWin) {
if (sennichite != SennichiteStatus::kWin || sennichite != SennichiteStatus::kLose) {
return move;
}

Expand Down Expand Up @@ -240,7 +240,7 @@ namespace stoat::datagen {
if (sennichite == SennichiteStatus::kDraw) {
outcome = format::Outcome::kDraw;
break;
} else if (sennichite == SennichiteStatus::kWin) {
} else if (sennichite == SennichiteStatus::kWin || sennichite == SennichiteStatus::kLose) {
const std::scoped_lock lock{s_printMutex};

auto& errStream = getErrStream(outDir);
Expand Down
14 changes: 10 additions & 4 deletions src/position.cpp
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Expand Up @@ -300,20 +300,26 @@ namespace stoat {

SennichiteStatus Position::testSennichite(bool cuteChessWorkaround, std::span<const u64> keyHistory, i32 limit)
const {
const auto end = std::max(0, static_cast<i32>(keyHistory.size()) - limit - 1);
const auto end = std::min(static_cast<i32>(keyHistory.size()), limit);

i32 repetitions = 1;

for (i32 i = static_cast<i32>(keyHistory.size()) - 4; i >= end; i -= 2) {
if (keyHistory[i] == key()) {
for (i32 i = 4; i <= end; i += 2) {
if (keyHistory[keyHistory.size() - i] == key()) {
--repetitions;
if (repetitions == 0) {
// Older cutechess versions do not handle perpetuals
// properly - work around that to avoid illegal moves
if (cuteChessWorkaround) {
return isInCheck() ? SennichiteStatus::kWin : SennichiteStatus::kDraw;
} else {
return m_consecutiveChecks[stm().idx()] >= 2 ? SennichiteStatus::kWin : SennichiteStatus::kDraw;
if (i / 2 <= m_consecutiveChecks[stm().idx()]) {
return SennichiteStatus::kWin;
} else if (i / 2 <= m_consecutiveChecks[stm().flip().idx()]) {
return SennichiteStatus::kLose;
} else {
return SennichiteStatus::kDraw;
}
}
}
}
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3 changes: 2 additions & 1 deletion src/position.h
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Expand Up @@ -100,7 +100,8 @@ namespace stoat {
enum class SennichiteStatus {
kNone = 0,
kDraw,
kWin, // perpetual check by opponent
kWin, // perpetual check by opponent
kLose, // perpetual check
};

namespace eval::nnue {
Expand Down
10 changes: 7 additions & 3 deletions src/search.cpp
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Expand Up @@ -610,10 +610,13 @@ namespace stoat {
Score score;

if (sennichite == SennichiteStatus::kWin) {
// illegal perpetual
--legalMoves;
continue;
} else if (sennichite == SennichiteStatus::kDraw) {
} else if (sennichite == SennichiteStatus::kLose) {
score = kScoreMate - ply - 1;
goto skipSearch;
}
else if (sennichite == SennichiteStatus::kDraw) {
score = drawScore(thread.loadNodes());
goto skipSearch;
} else if (pos.isEnteringKingsWin()) {
Expand Down Expand Up @@ -776,8 +779,9 @@ namespace stoat {
Score score;

if (sennichite == SennichiteStatus::kWin) {
// illegal perpetual
continue;
} else if (sennichite == SennichiteStatus::kLose) {
score = kScoreMate - ply - 1;
} else if (sennichite == SennichiteStatus::kDraw) {
score = drawScore(thread.loadNodes());
} else {
Expand Down
2 changes: 1 addition & 1 deletion version.txt
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@@ -1 +1 @@
0.1.100
0.1.101