Entity Blackboard: Structured Agent Memory for Long Document Summarization

Ruyi Liu, Guanyun Zou, Hongliang Dai, Piji Li


Abstract
Hierarchical merging is commonly used to summarize long documents by splitting the input into chunks, summarizing each chunk independently, and merging the results into a final summary. However, because each chunk is processed independently, entity state changes across chunks are not tracked, leading to coherence and consistency issues in the final summary. We propose EntityBB (Entity Blackboard), an agent memory framework that equips chunk-based LLM summarizers with structured entity memory. During sequential chunk processing, the model records and updates entity states through tool calls, while automatic safeguards and model-driven rejection limit noisy writes. Experiments on three long document summarization benchmarks show that EntityBB consistently improves over a controlled hierarchical merging baseline across ROUGE and BERTScore, while NarrativeFactScore indicates improved source-grounded factuality. Targeted human and LLM-as-a-Judge evaluations further indicate fewer entity-level issues and higher judged summary quality.
Anthology ID:
2026.findings-emnlp.384
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
8099–8114
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.384/
DOI:
Bibkey:
Cite (ACL):
Ruyi Liu, Guanyun Zou, Hongliang Dai, and Piji Li. 2026. Entity Blackboard: Structured Agent Memory for Long Document Summarization. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 8099–8114, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Entity Blackboard: Structured Agent Memory for Long Document Summarization (Liu et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.384.pdf