# Tokenizer Mismatch — Guardrails and Fix Patterns Stabilize multilingual retrieval when the query and the index segment text differently. Typical pain shows up in Chinese, Japanese, Thai, Khmer, and any mixed-script corpus where whitespace is unreliable. --- ## Open these first * Visual map and recovery: [rag-architecture-and-recovery.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/rag-architecture-and-recovery.md) * Chunking checklist: [chunking-checklist.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/chunking-checklist.md) * Retrieval traceability: [retrieval-traceability.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/retrieval-traceability.md) * Schema fence for snippets: [data-contracts.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/data-contracts.md) * Embedding vs meaning: [embedding-vs-semantic.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/embedding-vs-semantic.md) Related multilingual pages in this folder: * Guide overview: [multilingual\_guide.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/GlobalFixMap/Language/multilingual_guide.md) * Script direction and mixing: [script\_mixing.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/GlobalFixMap/Language/script_mixing.md) * Locale and analyzer drift: [locale\_drift.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/GlobalFixMap/Language/locale_drift.md) * HyDE behavior across languages: [hyde\_multilingual.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/GlobalFixMap/Language/hyde_multilingual.md) --- ## Core acceptance targets * ΔS(question, retrieved) ≤ 0.45 for both English and target language * Coverage of target section ≥ 0.70 after repair * λ remains convergent across three paraphrases in the target language * E\_resonance flat across 50+ queries that mix scripts and numbers --- ## What this failure looks like | Symptom | Likely cause | Where to fix | | -------------------------------------------------------------------------- | -------------------------------------------------------------------------- | ------------------------------------------------------------------- | | Chinese or Japanese queries return no hits, while English paraphrase works | Query tokenizer uses whitespace, index uses character n-gram or vice versa | Switch to language-aware analyzers; unify query and index pipelines | | BM25 recall ok but citations land in the wrong sub-section | Token boundary misalignment between chunker and retriever | Rechunk with stable boundaries and same segmentation as the store | | Hybrid retrieval underperforms a single retriever | Mixed analyzers per stage, reranker sees inconsistent text | Normalize text pre-rerank and re-embed with the same tokenizer | | High similarity yet wrong meaning | Embedding model trained with different normalization or casing rules | Re-embed with consistent normalization; see Embedding ≠ Semantic | --- ## Fix in 60 seconds 1. **Measure ΔS** Run the same question in English and the target language. If ΔS differs by more than 0.15, suspect tokenizer mismatch. 2. **Probe λ\_observe** Paraphrase the non-English query three ways. If λ flips between convergent and divergent when you reorder headers, lock the prompt schema and proceed to analyzer unification. 3. **Apply the smallest structural change** * If your store is lexical: set **the same analyzer** for both index and query. * If your store is vector-only: normalize and segment **before** embedding, then re-embed a small gold set and verify. 4. **Verify** Coverage ≥ 0.70 and ΔS ≤ 0.45 on three paraphrases. Log the analyzer and normalization used. --- ## Minimal repair recipes by stack ### Elasticsearch / OpenSearch * Pick **one** analyzer for CJK fields and use it for both indexing and queries. Options that work in practice: * Japanese: `kuromoji` * Korean: `nori` * Chinese: `smartcn` or ICU + bigram filter * Add a keyword subfield for exact filters and rerank features. * Normalize to NFC and convert full-width to half-width for digits and ASCII. * Rebuild only the affected indices, then re-run the gold set. See: [retrieval-playbook.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/retrieval-playbook.md) ### BM25 in code or light stores (Chroma, sqlite FTS, etc.) * For CJK and Thai, use **character bigrams or trigrams** on both index and query. * Remove language-specific stopwords when language is unknown. * Keep punctuation normalization consistent across stages. See: [pattern\_query\_parsing\_split.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/patterns/pattern_query_parsing_split.md) ### Vector stores (FAISS, Milvus, pgvector, Weaviate, Qdrant) * Do not trust the model to “fix” segmentation. Pre-normalize text: * Unicode NFC * Lowercase where appropriate * Full-width to half-width for numbers and ASCII * Optional: insert spaces between CJK and ASCII tokens for stable sentencepiece * Re-embed both corpus and queries with the exact same normalization script. * If recall is still low, add a lexical recall stage, then rerank. See: [vectorstore-fragmentation.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/patterns/pattern_vectorstore_fragmentation.md) --- ## Diagnostic checklist * Query and index use **the same** tokenizer or analyzer. * Chunker segmentation matches the retriever segmentation. * Unicode form is consistent; half-width and diacritics normalized. * Mixed scripts do not flip direction or join tokens incorrectly. * Rerank stage sees normalized text, not raw captures. --- ## Copy-paste tests **Three-language ΔS probe** ``` Question: "" Languages: English, Chinese, Japanese For each language: 1. Retrieve top-k with your current settings. 2. Compute ΔS(question, retrieved). Record λ_state. 3. If ΔS differs by > 0.15 across languages, suspect tokenizer mismatch. Return a table: language, ΔS, λ_state, analyzer/normalizer used. ``` **Schema lock for reruns** ``` Header order: citations → facts → synthesis → caveats. If λ flips when you change header order, lock this schema and fix analyzers first. ``` --- ## When to escalate * ΔS remains ≥ 0.60 after analyzer unification. Re-chunk with stable boundaries and re-embed a gold slice. Open: [chunking-checklist.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/chunking-checklist.md) * Citations still jump across sections after repair. Enforce snippet schema and forbid cross-section reuse. Open: [data-contracts.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/data-contracts.md), [retrieval-traceability.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/retrieval-traceability.md) * Hybrid beats single only sometimes. Align analyzers in both stages and rerank deterministically. Open: [rerankers.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/rerankers.md) --- ### 🔗 Quick-Start Downloads (60 sec) | Tool | Link | 3-Step Setup | | -------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------ | ---------------------------------------------------------------------------------------- | | **WFGY 1.0 PDF** | [Engine Paper](https://github.com/onestardao/WFGY/blob/main/I_am_not_lizardman/WFGY_All_Principles_Return_to_One_v1.0_PSBigBig_Public.pdf) | 1️⃣ Download · 2️⃣ Upload to your LLM · 3️⃣ Ask “Answer using WFGY + \” | | **TXT OS (plain-text OS)** | [TXTOS.txt](https://github.com/onestardao/WFGY/blob/main/OS/TXTOS.txt) | 1️⃣ Download · 2️⃣ Paste into any LLM chat · 3️⃣ Type “hello world” — OS boots instantly | --- ### 🧭 Explore More | Module | Description | Link | | ------------------------ | ---------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------- | | WFGY Core | WFGY 2.0 engine is live: full symbolic reasoning architecture and math stack | [View →](https://github.com/onestardao/WFGY/tree/main/core/README.md) | | Problem Map 1.0 | Initial 16-mode diagnostic and symbolic fix framework | [View →](https://github.com/onestardao/WFGY/tree/main/ProblemMap/README.md) | | Problem Map 2.0 | RAG-focused failure tree, modular fixes, and pipelines | [View →](https://github.com/onestardao/WFGY/blob/main/ProblemMap/rag-architecture-and-recovery.md) | | Semantic Clinic Index | Expanded failure catalog: prompt injection, memory bugs, logic drift | [View →](https://github.com/onestardao/WFGY/blob/main/ProblemMap/SemanticClinicIndex.md) | | Semantic Blueprint | Layer-based symbolic reasoning & semantic modulations | [View →](https://github.com/onestardao/WFGY/tree/main/SemanticBlueprint/README.md) | | Benchmark vs GPT-5 | Stress test GPT-5 with full WFGY reasoning suite | [View →](https://github.com/onestardao/WFGY/tree/main/benchmarks/benchmark-vs-gpt5/README.md) | | 🧙‍♂️ Starter Village 🏡 | New here? Lost in symbols? Click here and let the wizard guide you through | [Start →](https://github.com/onestardao/WFGY/blob/main/StarterVillage/README.md) | --- > 👑 **Early Stargazers: [See the Hall of Fame](https://github.com/onestardao/WFGY/tree/main/stargazers)** GitHub stars ⭐ [WFGY Engine 2.0](https://github.com/onestardao/WFGY/blob/main/core/README.md) is already unlocked. ⭐ Star the repo to help others discover it and unlock more on the [Unlock Board](https://github.com/onestardao/WFGY/blob/main/STAR_UNLOCKS.md).
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