Training-free semantic trees beat full-context prompting: +1.72 QA-F1 with 58.55% less context

_reachsumit · x · 2026-10-28

An arXiv paper introduces a training-free framework that builds a reusable semantic hierarchy of a long document in a single generation, linking node descriptions to source spans. For a query, structural-semantic scoring and fine-grained lexical attribution select shared source nodes, unioned with ancestor context to preserve structure and complete local text. Across four frontier answer models on three LongBench tasks, it improves average QA-F1 by 1.72 points over full-context prompting while cutting answer-context length by 58.55%. Code is open-sourced.

Original post →

More from Research

Research channel →