PageIndex: Retrieval by Reasoning over the Hierarchy

① a tree, no traversal→② score-based, both ways→③ LLM-guided instead→④ traversal learned→⑤ multimodal
the hierarchy index · fetched whole title pages X100 User Manual1-52 1. Introduction1-4 2. Safety5-9 2.1 Operating Env.7-8 5. Maintenance30-44 5.1 Cleaning30-33 5.2 Filter34-37 5.3 Battery38-41 5.4 Firmware42-44 6. FAQ45-48 every node carries its own page range a parent range = union of its children 1 · reason over it → which pages to read LLM sees titles + ranges · no page text yet Thinking: intervals live under Maintenance; heat may matter → check Operating Env. too picks titles copies their stored range 2.1 Operating Env. 7-8 5.3 Battery 38-41 get_page_content("7-8, 38-41") the numbers are copied from the index, never guessed one call carries several ranges = several sections choosing a parent instead (5. Maintenance → 30-44) pulls every subsection 2 · read those pages, then judge p.7-8 p.38-41 · 5.3 Battery fan 12 mo battery 6 mo found: battery → 6 months and from p.7-8 · halve it in high heat enough to answer? the LLM itself decides · no scorer it may also follow a reference it just read ("see Appendix G") back into step 1 output enough → answer "every 6 months, 3 in high heat" + the sections it opened 5.3 Battery · 2.1 Operating Env. as citations sections, not chunks a reader, not a retriever not enough ↻ pick other titles, call again state between rounds = the tool history already in the prompt · what it read stays there, there is no note store
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