EmbGen: Teaching with Reassembled Corpora

Fuente: arXiv
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Main Authors: Lenin, Arun K, Rouse, Kai, Nicastro, Andrea, Leontjeva, Anna
Format: Preprint
Published: 2026
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author Lenin, Arun K
Rouse, Kai
Nicastro, Andrea
Leontjeva, Anna
author_facet Lenin, Arun K
Rouse, Kai
Nicastro, Andrea
Leontjeva, Anna
contents Adapting small instruction-tuned models to specialized domains often relies on supervised fine-tuning (SFT) on curated instruction-response examples, which is expensive to collect at scale. Synthetic training examples generated by a teacher LLM from a domain corpus can reduce this cost, but existing pipelines can produce homogenized outputs and do not consistently capture cross-passage or cross-document dependencies. We introduce EmbGen, a synthetic data generation pipeline that decomposes a corpus into entity-description pairs, reassembles them using semantic structure inferred from embedding similarity, and then generates question-answer (QA) pairs via proximity, intra-cluster, and inter-cluster sampling with cluster-specialized system prompts. We evaluate EmbGen against EntiGraph, InstructLab and Knowledge-Instruct on three datasets of varied semantic heterogeneity, under fixed token budgets (5 and 20 million tokens). We use lexical overlap metrics, an LLM-as-a-judge rubric, and Binary Accuracy, a composed metric combining Factual Accuracy and Completeness for evaluation. EmbGen improves Binary Accuracy on the most heterogeneous dataset by 12.5% at 5M and 88.9% at 20M tokens budget, relative to the strongest baseline, while remaining competitive across other datasets with lower heterogeneity.
format Preprint
id arxiv_https___arxiv_org_abs_2605_19394
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle EmbGen: Teaching with Reassembled Corpora
Lenin, Arun K
Rouse, Kai
Nicastro, Andrea
Leontjeva, Anna
Computation and Language
Artificial Intelligence
68T05: Learning and adaptive systems
Adapting small instruction-tuned models to specialized domains often relies on supervised fine-tuning (SFT) on curated instruction-response examples, which is expensive to collect at scale. Synthetic training examples generated by a teacher LLM from a domain corpus can reduce this cost, but existing pipelines can produce homogenized outputs and do not consistently capture cross-passage or cross-document dependencies. We introduce EmbGen, a synthetic data generation pipeline that decomposes a corpus into entity-description pairs, reassembles them using semantic structure inferred from embedding similarity, and then generates question-answer (QA) pairs via proximity, intra-cluster, and inter-cluster sampling with cluster-specialized system prompts. We evaluate EmbGen against EntiGraph, InstructLab and Knowledge-Instruct on three datasets of varied semantic heterogeneity, under fixed token budgets (5 and 20 million tokens). We use lexical overlap metrics, an LLM-as-a-judge rubric, and Binary Accuracy, a composed metric combining Factual Accuracy and Completeness for evaluation. EmbGen improves Binary Accuracy on the most heterogeneous dataset by 12.5% at 5M and 88.9% at 20M tokens budget, relative to the strongest baseline, while remaining competitive across other datasets with lower heterogeneity.
title EmbGen: Teaching with Reassembled Corpora
topic Computation and Language
Artificial Intelligence
68T05: Learning and adaptive systems
url https://arxiv.org/abs/2605.19394