BengaliNormalizer's khio rule tests U+09BF (vowel sign I) instead of U+09B7 (SSA), so the common conjunct ক্ষ (KA+HASANTA+SSA) is never folded to KHA / KA+KHA as the rule comment and the cited paper say, and the malformed KA+HASANTA+VOWEL SIGN I is folded instead

Finding LFV-667Area: analysis-common / Bengali normalizer (BengaliNormalizer.normalize; BengaliNormalizationFilter, BengaliAnalyzer and the 'bengaliNormalization' factory)Priority: lowImpact: minorNovelty: new

Finding page for LFV-667

AI-assisted finding, confirmed by automated checks, not yet triaged by a human Lucene committer. This site files nothing upstream.

What it shows

You analyze Bengali text with the stock BengaliAnalyzer or BengaliNormalizationFilter. Its normalizer has a rule labelled 'Khio (Ka + Hoshonto + Murdorno Sh)' and says it implements a cited paper, which folds the conjunct ক্ষ (KA+HASANTA+SSA) to খ (KHA) at the start of a word and to কখ (KA+KHA) elsewhere, so ক্ষমা should normalize to খমা. Instead the rule's condition compares the third character with U+09BF (BENGALI VOWEL SIGN I) instead of U+09B7 (BENGALI LETTER SSA), one hex digit off, so the rule never fires on real text: ক্ষমা becomes ক্সমা and পরীক্ষা becomes পরিক্সা (only the separate 'All sh' rule applies, SSA to SA), while the malformed sequence KA+HASANTA+VOWEL SIGN I is folded instead (ক্িমা becomes খমা), with no error.

The test shows that BengaliNormalizer's "Khio (Ka + Hoshonto + Murdorno Sh)" rule checks U+09BF (vowel sign I) instead of U+09B7 (SSA), so it never folds the conjunct ক্ষ.

Expected vs actual

Expected: ক্ষমা (U+0995 U+09CD U+09B7 U+09AE U+09BE) normalizes to খমা (U+0996 U+09AE U+09BE). Actual (-ea and -da): ক্সমা (U+0995 U+09CD U+09B8 U+09AE U+09BE).

Files

• src/org/apache/lucene/analysis/bn/TestBengaliKhioRule.java (JUnit test)

Run it

• Tested on Lucene main e1faeba08bde (2026-11-02): still reproduces.
• Tested on Lucene main 645d4fe14a20 (2026-10-28): reproduced.
• Recorded outcome of run 1 on Lucene main 645d4fe14a20: 1 test(s) run, 1 failed.
• How to read the outcome: a failing test is the finding reproducing (the failure message states expected against actual).
• Seeds: a rerun with the same seed replays the same random choices. Assertions off (-da -dsa -Dtests.asserts=false) is the production-like setting.

# Lucene checkout at the tested commit, built with: ./gradlew --no-daemon assemble   (JDK 25)
LUCENE=/path/to/lucene; V=12.0.0-SNAPSHOT
CP=$LUCENE/lucene/core/build/libs/lucene-core-$V.jar
CP=$CP:$LUCENE/lucene/codecs/build/libs/lucene-codecs-$V.jar
CP=$CP:$LUCENE/lucene/test-framework/build/libs/lucene-test-framework-$V.jar
CP=$CP:$LUCENE/lucene/analysis/common/build/libs/lucene-analysis-common-$V.jar
CP=$CP:randomizedtesting-runner-2.9.2.jar:junit-4.13.2.jar:hamcrest-3.0.jar   # test-framework dependencies (Maven Central)
CP=$CP:junit-platform-console-standalone-6.1.3.jar   # JUnit Platform console launcher (Maven Central)

javac -d classes -cp "$CP" $(find src -name '*.java')

# run 1: assertions on, seed DEADBEEF
java -ea -esa --add-modules jdk.incubator.vector --enable-native-access=ALL-UNNAMED -Dtests.seed=DEADBEEF \
     -cp "classes:$CP" org.junit.platform.console.ConsoleLauncher \
     execute --select-class org.apache.lucene.analysis.bn.TestBengaliKhioRule

Gradle alternative: copy the test into the matching module's src/test/ tree of the checkout and run ./gradlew -p lucene/<module> test --tests <class> -Ptests.seed=<seed> (add -Ptests.asserts=false for a run without assertions).

Feedback

Open an issue in lucene-ai-bug-hunt. Please do not open issues or pull requests in apache/lucene about this finding unless a Lucene committer agrees it should be filed.

Snapshot of 2026-11-04. AI-assisted; not yet triaged by a human Lucene committer. Feedback: open an issue in lucene-ai-bug-hunt.