{
  "id": 684332,
  "title": "17th Place Solution — Deep Past Challenge ",
  "url": "/competitions/deep-past-initiative-machine-translation/discussion/684332",
  "author_name": "Nguyên Nguyên",
  "post_date": "2026-03-24T13:57:22.100000",
  "votes": 7,
  "comment_count": 0,
  "views": 0,
  "content": "<hr>\n<h2>TL;DR</h2>\n<p>Our approach is based on an ensemble of ByT5 models supported by a multi-stage, Gemini-driven data construction pipeline. Final predictions were generated using a <strong>Weighted MBR Decoding</strong> strategy.</p>\n<p><strong>Core Differentiators:</strong></p>\n<ul>\n<li><strong>Data-Centric Pipeline:</strong> Performance gains were driven primarily by data alignment, normalization, and expansion rather than model scaling.</li>\n<li><strong>Character-Level Modeling:</strong> ByT5 proved robust to the high entropy and noise of Akkadian transliterations.</li>\n<li><strong>Metric-Aware Decoding:</strong> We replaced standard decoding with an Optuna-tuned weighted MBR framework to better align with evaluation metrics.</li>\n</ul>\n<hr>\n<h2>Models</h2>\n<p>We evaluated multiple architectures, including decoder-only LLMs (e.g., Qwen series), but they underperformed due to:</p>\n<ul>\n<li>The <strong>low-resource setting</strong></li>\n<li>The <strong>character-level irregularity</strong> of transliterations</li>\n</ul>\n<p><strong>Best-performing models:</strong></p>\n<p>ByT5 variants: We experimented with base, large, and XL models. Although larger models sometimes achieved higher private scores, they were less stable and underperformed on validation. We therefore prioritized the robustness of ByT5-base. </p>\n<hr>\n<h2>Data</h2>\n<p>Performance was primarily bottlenecked by <strong>data quality and alignment</strong>, not model capacity. We built a unified corpus from multiple heterogeneous sources using a <strong>Gemini-based pipeline</strong>.</p>\n<h3>Data Sources &amp; Processing</h3>\n<ul>\n<li><p><strong>Training Data (Document → Sentence Alignment):</strong>\nThe original dataset was provided at the document level. We used Gemini to segment it into sentence-level pairs, significantly improving alignment and increasing the number of effective training samples.</p></li>\n<li><p><strong>Publications (OCR Data):</strong>\nNoisy OCR text was segmented and normalized using Gemini, improving coverage of rare tokens despite high noise levels.</p></li>\n<li><p><strong>Published Text (Pseudo-Labeling):</strong>\nWe generated pseudo-parallel data via <strong>few-shot prompting with injected Akkadian lexicons</strong>, improving consistency for rare words and named entities.</p></li>\n<li><p><strong>PDF Sources (Multimodal Extraction):</strong>\nFor image-heavy PDFs, we designed a prompt pipeline (few-shot + lexicon) to directly extract aligned sentence pairs.</p></li>\n<li><p><strong>Cross-Lingual Normalization:</strong>\nNon-English segments (e.g., Turkish) were translated and aligned into English using Gemini.</p></li>\n</ul>\n<h3>Key Insight</h3>\n<p>Transforming <strong>heterogeneous, noisy, document-level data into sentence-aligned pairs</strong> was the single most impactful improvement in our pipeline.</p>\n<hr>\n<h2>Preprocessing</h2>\n<p>While preprocessing had limited direct impact on validation scores, it was essential for:</p>\n<ul>\n<li>Stabilizing training</li>\n<li>Reducing variance across sources</li>\n<li>Ensuring consistent formatting</li>\n</ul>\n<hr>\n<h2>Validation Strategy</h2>\n<p>Instead of relying solely on standard cross-validation, we focused on <strong>data-centric validation</strong>:</p>\n<ul>\n<li>We experimented with different <strong>combinations of data sources</strong></li>\n<li>Selected the <strong>top 3 performing mixtures</strong> to train our final ensemble models</li>\n</ul>\n<p>This was critical due to:</p>\n<ul>\n<li>Large <strong>distribution gaps</strong> between sources</li>\n<li>Varying <strong>noise levels</strong> across datasets</li>\n</ul>\n<p><strong>Observation:</strong></p>\n<ul>\n<li>chrF++ was consistently ~10 points higher than BLEU\n→ This directly informed our <strong>metric weighting in MBR reranking</strong></li>\n</ul>\n<hr>\n<h2>Training Logistics</h2>\n<ul>\n<li><p><strong>Single-model plateau:</strong> ~38 LB score</p></li>\n<li><p>Increasing sequence length did not help → bottleneck was data quality</p></li>\n<li><p><strong>Discarded methods:</strong></p>\n<ul>\n<li>Bidirectional training</li>\n<li>Aggressive mixing</li>\n<li>SWA\n→ All reduced stability or performance</li></ul></li>\n</ul>\n<hr>\n<h2>Inference &amp; Ensembling</h2>\n<p>Final system: <strong>3-model ensemble with cross-model candidate pooling</strong></p>\n<p><strong>Pipeline:</strong></p>\n<ol>\n<li><p><strong>Candidate Generation</strong></p>\n<ul>\n<li>Beam search</li>\n<li>Multi-temperature sampling (to increase diversity)</li></ul></li>\n<li><p><strong>Cross-Pooling</strong></p>\n<ul>\n<li>Merge and deduplicate candidates from all models</li></ul></li>\n</ol>\n<hr>\n<h2>Weighted MBR Reranking (Optuna-Tuned)</h2>\n<p>We implemented a <strong>metric-aware MBR decoding strategy</strong>, optimized using Optuna.</p>\n<p><strong>Tuned parameters:</strong></p>\n<ul>\n<li>Metric weights (chrF++, BLEU, Jaccard)</li>\n<li>Length penalty</li>\n<li>Candidate pool size</li>\n</ul>\n<p><strong>Key idea:</strong></p>\n<p>Instead of selecting the highest-probability output, we select the candidate that <strong>maximizes agreement under evaluation metrics across models</strong>.</p>\n<p><strong>Result:</strong></p>\n<ul>\n<li>Comparable or better than beam search and voting</li>\n<li>More robust to noisy candidates</li>\n</ul>\n<hr>\n<h2>Final Thoughts</h2>\n<p>This competition reinforced a key lesson:</p>\n<blockquote>\n  <p>In low-resource settings, <strong>data quality and alignment dominate model scaling</strong>.</p>\n</blockquote>\n<p>Our strongest gains came from:</p>\n<ul>\n<li>Converting document-level data into aligned sentences</li>\n<li>Expanding coverage via pseudo-labeling and OCR</li>\n<li>Using metric-aware decoding instead of standard generation</li>\n</ul>\n<hr>",
  "messages": [
    {
      "id": 3427761,
      "postDate": "2026-03-24T13:57:22.100Z",
      "content": "<hr>\n<h2>TL;DR</h2>\n<p>Our approach is based on an ensemble of ByT5 models supported by a multi-stage, Gemini-driven data construction pipeline. Final predictions were generated using a <strong>Weighted MBR Decoding</strong> strategy.</p>\n<p><strong>Core Differentiators:</strong></p>\n<ul>\n<li><strong>Data-Centric Pipeline:</strong> Performance gains were driven primarily by data alignment, normalization, and expansion rather than model scaling.</li>\n<li><strong>Character-Level Modeling:</strong> ByT5 proved robust to the high entropy and noise of Akkadian transliterations.</li>\n<li><strong>Metric-Aware Decoding:</strong> We replaced standard decoding with an Optuna-tuned weighted MBR framework to better align with evaluation metrics.</li>\n</ul>\n<hr>\n<h2>Models</h2>\n<p>We evaluated multiple architectures, including decoder-only LLMs (e.g., Qwen series), but they underperformed due to:</p>\n<ul>\n<li>The <strong>low-resource setting</strong></li>\n<li>The <strong>character-level irregularity</strong> of transliterations</li>\n</ul>\n<p><strong>Best-performing models:</strong></p>\n<p>ByT5 variants: We experimented with base, large, and XL models. Although larger models sometimes achieved higher private scores, they were less stable and underperformed on validation. We therefore prioritized the robustness of ByT5-base. </p>\n<hr>\n<h2>Data</h2>\n<p>Performance was primarily bottlenecked by <strong>data quality and alignment</strong>, not model capacity. We built a unified corpus from multiple heterogeneous sources using a <strong>Gemini-based pipeline</strong>.</p>\n<h3>Data Sources &amp; Processing</h3>\n<ul>\n<li><p><strong>Training Data (Document → Sentence Alignment):</strong>\nThe original dataset was provided at the document level. We used Gemini to segment it into sentence-level pairs, significantly improving alignment and increasing the number of effective training samples.</p></li>\n<li><p><strong>Publications (OCR Data):</strong>\nNoisy OCR text was segmented and normalized using Gemini, improving coverage of rare tokens despite high noise levels.</p></li>\n<li><p><strong>Published Text (Pseudo-Labeling):</strong>\nWe generated pseudo-parallel data via <strong>few-shot prompting with injected Akkadian lexicons</strong>, improving consistency for rare words and named entities.</p></li>\n<li><p><strong>PDF Sources (Multimodal Extraction):</strong>\nFor image-heavy PDFs, we designed a prompt pipeline (few-shot + lexicon) to directly extract aligned sentence pairs.</p></li>\n<li><p><strong>Cross-Lingual Normalization:</strong>\nNon-English segments (e.g., Turkish) were translated and aligned into English using Gemini.</p></li>\n</ul>\n<h3>Key Insight</h3>\n<p>Transforming <strong>heterogeneous, noisy, document-level data into sentence-aligned pairs</strong> was the single most impactful improvement in our pipeline.</p>\n<hr>\n<h2>Preprocessing</h2>\n<p>While preprocessing had limited direct impact on validation scores, it was essential for:</p>\n<ul>\n<li>Stabilizing training</li>\n<li>Reducing variance across sources</li>\n<li>Ensuring consistent formatting</li>\n</ul>\n<hr>\n<h2>Validation Strategy</h2>\n<p>Instead of relying solely on standard cross-validation, we focused on <strong>data-centric validation</strong>:</p>\n<ul>\n<li>We experimented with different <strong>combinations of data sources</strong></li>\n<li>Selected the <strong>top 3 performing mixtures</strong> to train our final ensemble models</li>\n</ul>\n<p>This was critical due to:</p>\n<ul>\n<li>Large <strong>distribution gaps</strong> between sources</li>\n<li>Varying <strong>noise levels</strong> across datasets</li>\n</ul>\n<p><strong>Observation:</strong></p>\n<ul>\n<li>chrF++ was consistently ~10 points higher than BLEU\n→ This directly informed our <strong>metric weighting in MBR reranking</strong></li>\n</ul>\n<hr>\n<h2>Training Logistics</h2>\n<ul>\n<li><p><strong>Single-model plateau:</strong> ~38 LB score</p></li>\n<li><p>Increasing sequence length did not help → bottleneck was data quality</p></li>\n<li><p><strong>Discarded methods:</strong></p>\n<ul>\n<li>Bidirectional training</li>\n<li>Aggressive mixing</li>\n<li>SWA\n→ All reduced stability or performance</li></ul></li>\n</ul>\n<hr>\n<h2>Inference &amp; Ensembling</h2>\n<p>Final system: <strong>3-model ensemble with cross-model candidate pooling</strong></p>\n<p><strong>Pipeline:</strong></p>\n<ol>\n<li><p><strong>Candidate Generation</strong></p>\n<ul>\n<li>Beam search</li>\n<li>Multi-temperature sampling (to increase diversity)</li></ul></li>\n<li><p><strong>Cross-Pooling</strong></p>\n<ul>\n<li>Merge and deduplicate candidates from all models</li></ul></li>\n</ol>\n<hr>\n<h2>Weighted MBR Reranking (Optuna-Tuned)</h2>\n<p>We implemented a <strong>metric-aware MBR decoding strategy</strong>, optimized using Optuna.</p>\n<p><strong>Tuned parameters:</strong></p>\n<ul>\n<li>Metric weights (chrF++, BLEU, Jaccard)</li>\n<li>Length penalty</li>\n<li>Candidate pool size</li>\n</ul>\n<p><strong>Key idea:</strong></p>\n<p>Instead of selecting the highest-probability output, we select the candidate that <strong>maximizes agreement under evaluation metrics across models</strong>.</p>\n<p><strong>Result:</strong></p>\n<ul>\n<li>Comparable or better than beam search and voting</li>\n<li>More robust to noisy candidates</li>\n</ul>\n<hr>\n<h2>Final Thoughts</h2>\n<p>This competition reinforced a key lesson:</p>\n<blockquote>\n  <p>In low-resource settings, <strong>data quality and alignment dominate model scaling</strong>.</p>\n</blockquote>\n<p>Our strongest gains came from:</p>\n<ul>\n<li>Converting document-level data into aligned sentences</li>\n<li>Expanding coverage via pseudo-labeling and OCR</li>\n<li>Using metric-aware decoding instead of standard generation</li>\n</ul>\n<hr>",
      "rawMarkdown": "---\n\n## TL;DR\n\nOur approach is based on an ensemble of ByT5 models supported by a multi-stage, Gemini-driven data construction pipeline. Final predictions were generated using a **Weighted MBR Decoding** strategy.\n\n**Core Differentiators:**\n\n* **Data-Centric Pipeline:** Performance gains were driven primarily by data alignment, normalization, and expansion rather than model scaling.\n* **Character-Level Modeling:** ByT5 proved robust to the high entropy and noise of Akkadian transliterations.\n* **Metric-Aware Decoding:** We replaced standard decoding with an Optuna-tuned weighted MBR framework to better align with evaluation metrics.\n\n---\n\n## Models\n\nWe evaluated multiple architectures, including decoder-only LLMs (e.g., Qwen series), but they underperformed due to:\n\n* The **low-resource setting**\n* The **character-level irregularity** of transliterations\n\n**Best-performing models:**\n\nByT5 variants: We experimented with base, large, and XL models. Although larger models sometimes achieved higher private scores, they were less stable and underperformed on validation. We therefore prioritized the robustness of ByT5-base. \n\n---\n\n## Data\n\nPerformance was primarily bottlenecked by **data quality and alignment**, not model capacity. We built a unified corpus from multiple heterogeneous sources using a **Gemini-based pipeline**.\n\n### Data Sources & Processing\n\n* **Training Data (Document → Sentence Alignment):**\n  The original dataset was provided at the document level. We used Gemini to segment it into sentence-level pairs, significantly improving alignment and increasing the number of effective training samples.\n\n* **Publications (OCR Data):**\n  Noisy OCR text was segmented and normalized using Gemini, improving coverage of rare tokens despite high noise levels.\n\n* **Published Text (Pseudo-Labeling):**\n  We generated pseudo-parallel data via **few-shot prompting with injected Akkadian lexicons**, improving consistency for rare words and named entities.\n\n* **PDF Sources (Multimodal Extraction):**\n  For image-heavy PDFs, we designed a prompt pipeline (few-shot + lexicon) to directly extract aligned sentence pairs.\n\n* **Cross-Lingual Normalization:**\n  Non-English segments (e.g., Turkish) were translated and aligned into English using Gemini.\n\n### Key Insight\n\nTransforming **heterogeneous, noisy, document-level data into sentence-aligned pairs** was the single most impactful improvement in our pipeline.\n\n---\n\n## Preprocessing\n\nWhile preprocessing had limited direct impact on validation scores, it was essential for:\n\n* Stabilizing training\n* Reducing variance across sources\n* Ensuring consistent formatting\n\n---\n\n## Validation Strategy\n\nInstead of relying solely on standard cross-validation, we focused on **data-centric validation**:\n\n* We experimented with different **combinations of data sources**\n* Selected the **top 3 performing mixtures** to train our final ensemble models\n\nThis was critical due to:\n\n* Large **distribution gaps** between sources\n* Varying **noise levels** across datasets\n\n**Observation:**\n\n* chrF++ was consistently ~10 points higher than BLEU\n  → This directly informed our **metric weighting in MBR reranking**\n\n---\n\n## Training Logistics\n\n* **Single-model plateau:** ~38 LB score\n* Increasing sequence length did not help → bottleneck was data quality\n* **Discarded methods:**\n\n  * Bidirectional training\n  * Aggressive mixing\n  * SWA\n    → All reduced stability or performance\n\n---\n\n## Inference & Ensembling\n\nFinal system: **3-model ensemble with cross-model candidate pooling**\n\n**Pipeline:**\n\n1. **Candidate Generation**\n\n   * Beam search\n   * Multi-temperature sampling (to increase diversity)\n\n2. **Cross-Pooling**\n\n   * Merge and deduplicate candidates from all models\n\n---\n\n## Weighted MBR Reranking (Optuna-Tuned)\n\nWe implemented a **metric-aware MBR decoding strategy**, optimized using Optuna.\n\n**Tuned parameters:**\n\n* Metric weights (chrF++, BLEU, Jaccard)\n* Length penalty\n* Candidate pool size\n\n**Key idea:**\n\nInstead of selecting the highest-probability output, we select the candidate that **maximizes agreement under evaluation metrics across models**.\n\n**Result:**\n\n* Comparable or better than beam search and voting\n* More robust to noisy candidates\n\n---\n\n## Final Thoughts\n\nThis competition reinforced a key lesson:\n\n> In low-resource settings, **data quality and alignment dominate model scaling**.\n\nOur strongest gains came from:\n\n* Converting document-level data into aligned sentences\n* Expanding coverage via pseudo-labeling and OCR\n* Using metric-aware decoding instead of standard generation\n\n---\n",
      "votes": 7
    }
  ],
  "comments": [],
  "raw_markdown_by_id": {
    "3427761": "---\n\n## TL;DR\n\nOur approach is based on an ensemble of ByT5 models supported by a multi-stage, Gemini-driven data construction pipeline. Final predictions were generated using a **Weighted MBR Decoding** strategy.\n\n**Core Differentiators:**\n\n* **Data-Centric Pipeline:** Performance gains were driven primarily by data alignment, normalization, and expansion rather than model scaling.\n* **Character-Level Modeling:** ByT5 proved robust to the high entropy and noise of Akkadian transliterations.\n* **Metric-Aware Decoding:** We replaced standard decoding with an Optuna-tuned weighted MBR framework to better align with evaluation metrics.\n\n---\n\n## Models\n\nWe evaluated multiple architectures, including decoder-only LLMs (e.g., Qwen series), but they underperformed due to:\n\n* The **low-resource setting**\n* The **character-level irregularity** of transliterations\n\n**Best-performing models:**\n\nByT5 variants: We experimented with base, large, and XL models. Although larger models sometimes achieved higher private scores, they were less stable and underperformed on validation. We therefore prioritized the robustness of ByT5-base. \n\n---\n\n## Data\n\nPerformance was primarily bottlenecked by **data quality and alignment**, not model capacity. We built a unified corpus from multiple heterogeneous sources using a **Gemini-based pipeline**.\n\n### Data Sources & Processing\n\n* **Training Data (Document → Sentence Alignment):**\n  The original dataset was provided at the document level. We used Gemini to segment it into sentence-level pairs, significantly improving alignment and increasing the number of effective training samples.\n\n* **Publications (OCR Data):**\n  Noisy OCR text was segmented and normalized using Gemini, improving coverage of rare tokens despite high noise levels.\n\n* **Published Text (Pseudo-Labeling):**\n  We generated pseudo-parallel data via **few-shot prompting with injected Akkadian lexicons**, improving consistency for rare words and named entities.\n\n* **PDF Sources (Multimodal Extraction):**\n  For image-heavy PDFs, we designed a prompt pipeline (few-shot + lexicon) to directly extract aligned sentence pairs.\n\n* **Cross-Lingual Normalization:**\n  Non-English segments (e.g., Turkish) were translated and aligned into English using Gemini.\n\n### Key Insight\n\nTransforming **heterogeneous, noisy, document-level data into sentence-aligned pairs** was the single most impactful improvement in our pipeline.\n\n---\n\n## Preprocessing\n\nWhile preprocessing had limited direct impact on validation scores, it was essential for:\n\n* Stabilizing training\n* Reducing variance across sources\n* Ensuring consistent formatting\n\n---\n\n## Validation Strategy\n\nInstead of relying solely on standard cross-validation, we focused on **data-centric validation**:\n\n* We experimented with different **combinations of data sources**\n* Selected the **top 3 performing mixtures** to train our final ensemble models\n\nThis was critical due to:\n\n* Large **distribution gaps** between sources\n* Varying **noise levels** across datasets\n\n**Observation:**\n\n* chrF++ was consistently ~10 points higher than BLEU\n  → This directly informed our **metric weighting in MBR reranking**\n\n---\n\n## Training Logistics\n\n* **Single-model plateau:** ~38 LB score\n* Increasing sequence length did not help → bottleneck was data quality\n* **Discarded methods:**\n\n  * Bidirectional training\n  * Aggressive mixing\n  * SWA\n    → All reduced stability or performance\n\n---\n\n## Inference & Ensembling\n\nFinal system: **3-model ensemble with cross-model candidate pooling**\n\n**Pipeline:**\n\n1. **Candidate Generation**\n\n   * Beam search\n   * Multi-temperature sampling (to increase diversity)\n\n2. **Cross-Pooling**\n\n   * Merge and deduplicate candidates from all models\n\n---\n\n## Weighted MBR Reranking (Optuna-Tuned)\n\nWe implemented a **metric-aware MBR decoding strategy**, optimized using Optuna.\n\n**Tuned parameters:**\n\n* Metric weights (chrF++, BLEU, Jaccard)\n* Length penalty\n* Candidate pool size\n\n**Key idea:**\n\nInstead of selecting the highest-probability output, we select the candidate that **maximizes agreement under evaluation metrics across models**.\n\n**Result:**\n\n* Comparable or better than beam search and voting\n* More robust to noisy candidates\n\n---\n\n## Final Thoughts\n\nThis competition reinforced a key lesson:\n\n> In low-resource settings, **data quality and alignment dominate model scaling**.\n\nOur strongest gains came from:\n\n* Converting document-level data into aligned sentences\n* Expanding coverage via pseudo-labeling and OCR\n* Using metric-aware decoding instead of standard generation\n\n---\n"
  }
}