From Graph to Text and Back: Semantic Fidelity in Automated Industrial Knowledge Graphs
Summary
When LLMs turn knowledge-graph triples into prose, they can invent facts or drop relations. That is unacceptable in industrial settings, and checking every output by hand is too expensive. The authors propose a self-supervised round-trip loop to solve this. One LLM writes text from a set of triples, and a second LLM extracts triples back from that text. The original and recovered graphs are then compared with a score that blends embedding cosine similarity and lexical overlap. This score also steers decoding: temperature and top-p go down when fidelity is low and up when it is high, which encourages varied outputs. Only candidates above a strict threshold are kept. On 250 small Wikipedia-derived graphs, the round-trip score agreed closely with human ratings, so it can stand in for expert review. Fine-tuning small LLaMA models on the filtered synthetic text improved triple extraction on automatic metrics and in blinded human evaluation. The approach needs no manual labels and no large teacher model.
Key points
- Data: 250 Wikipedia-based KGs, each with five triples about one subject. The authors say this size was chosen so experts could check outputs triple by triple, and that 5-triple chunks resemble subgraph retrieval in GraphRAG.
- Similarity score: it uses multilingual-e5-large-instruct embeddings plus a lexical metric, weighted by α. Thresholds and step sizes were set by grid search on a dev set, and the generation loop runs for N = 100 iterations per sample.
- Fine-tuned models: LLaMA2-7B, LLaMA3.2-3B and LLaMA3.2-1B, evaluated with BERTScore F1, ROUGE-L F1, BLEU-4 and A–E human ratings. Fine-tuned models received mostly top ratings, while base models clustered at the low end.
- Training cost and data volume: notable gains already appear with 25% of the synthetic data, which the authors attribute to data quality rather than quantity. Fine-tuning the 3B model takes about 15 minutes, and inference cost is unchanged.
- Release: code, checkpoints and datasets are published under the MIT license (github.com/KamyarZeinalipour/round-trip-kg). The authors suggest light expert spot-checks to limit bias drift and claim this still cuts annotation cost by over 90%.
Cite
@inproceedings{zeinalipour2026graph,
title = {{From Graph to Text and Back: Semantic Fidelity in Automated Industrial Knowledge Graphs}},
author = {Zeinalipour, Kamyar and Severini, Silvia and Borghini, Alessia and Cardarelli, Sara and Maggini, Marco and Gori, Marco},
booktitle = {Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 6: Industry Track)},
year = {2026},
doi = {10.18653/v1/2026.acl-industry.140},
url = {https://doi.org/10.18653/v1/2026.acl-industry.140}
}References
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