Schema-Hierarchical Soft Prompts for Structured Information Extraction

Soumyadeep Dey, Srikanth Tenneti, Bamdev Mishra, Shobhit Niranjan, Mayur Datar


Abstract
Structured information extraction at small-language-model scale is a routine production workload, yet each new task added to a serving stack can demand new task-specific model state. We propose a schema-hierarchical soft prompt: a small learned prefix, trained on a frozen backbone, that gives every JSON-schema node its own slot, orders the slots by the schema, and marks tree depth with learned embeddings. Used alone on the open USPTO-ORD patent task, it recovers most of a LoRA reference’s extraction quality while training more than an order of magnitude fewer parameters, and ablations attribute the gain to depth and schema order rather than token count. Used with a LoRA adapter on an internal booking task, the same slots stabilize one of two held-out categories, so we report this as a bounded mechanism study rather than a general gain. Inference-time slot replacement indicates that position supplies the schema scaffold while learned content stabilizes generation. Measured serving gives a far smaller task artifact and higher throughput than multi-LoRA as interleaved tasks grow. The soft-prompt module is available at https://github.com/microsoft/Hierarchical-Soft-Prompt.
Anthology ID:
2026.emnlp-industry.124
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Pepa Atanasova, Gholamreza Haffari, Minghan Wang
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
2127–2148
Language:
URL:
https://aclanthology.org/2026.emnlp-industry.124/
DOI:
Bibkey:
Cite (ACL):
Soumyadeep Dey, Srikanth Tenneti, Bamdev Mishra, Shobhit Niranjan, and Mayur Datar. 2026. Schema-Hierarchical Soft Prompts for Structured Information Extraction. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track, pages 2127–2148, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Schema-Hierarchical Soft Prompts for Structured Information Extraction (Dey et al., EMNLP 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.emnlp-industry.124.pdf