REVIEW 2 major objections 7 minor 31 references
Extract Information from Hybrid Long Documents Leveraging LLMs: A Framework and Dataset
T0 review · 2 major / 7 minor · reviewed 2026-08-10 · deepseek-v4-flash
Pith's one-line read LLMs can pull numbers from hybrid long documents by retrieving, summarizing, and extracting only the relevant segments.
desk verdict Systematic ablations and a new financial dataset, but the undefined baseline and test-set tuning make the headline numbers provisional; worth reviewing with major revisions. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
The central object is the AIE pipeline with four modules: Segmentation, Retrieval, Summarization, and Extraction. Segmentation serializes tables into plain text, splits oversized elements, and merges adjacent small ones; Retrieval scores each segment against the query keyword using a sentence-embedding model (SentenceTransformer) and keeps the top K=3 segments; Summarization applies the Refine strategy, iteratively updating a running summary with each retrieved segment; Extraction uses a tailored prompt to return the precise value. The evaluation machinery is the RETA metric, which counts a prediction as correct when its relative error stays within a chosen tolerance, and the new FINE dataset of financial KPI values extracted from SEC filings.
What would settle it
Build a hybrid document in which the target value sits in a table with paraphrased headers and no exact keyword match, then check whether embedding retrieval selects the segment containing the value; if retrieval recall on such tables drops sharply, the central claim fails at its first step. A second check is to evaluate the R@n choice on a held-out split rather than the analyzed test set, since the R@3 advantage could shrink or reverse on a new split.
Extended reading notes
Core claim
The paper's central claim is that information extraction from hybrid long documents does not require processing the entire document or preserving the hierarchical structure of tables. A pipeline that segments the document, retrieves keyword-similar segments by embedding similarity, summarizes them iteratively with an LLM, and extracts the answer from the summary consistently outperforms a naive method that truncates the document, across financial reports, Wikipedia pages, and materials-science papers. On FINE, AIE with GPT-3.5 achieves an average accuracy of 69.93% versus 15.99% for the naive method. The paper also claims that a simple serialization of tables into plain text is sufficient for LLM table comprehension, and that the framework benefits from retrieving three segments, using the Refine summarization strategy, completing query keywords with company and time context, and using a single precision-aware example.
Load-bearing premise
The retrieval step trusts that embedding similarity between the query keyword and a document segment points to the segment containing the answer; if the keyword is phrased differently from the table or the table serializes poorly, retrieval can select the wrong segments and the later summarization and extraction steps cannot recover the value.
Editorial extensions
If this is right
- A retrieval-first pipeline removes the context-window ceiling: LLMs can work on arbitrarily long hybrid documents by reading only the segments that match the query.
- Plain-text table serialization is enough for LLM table understanding, so expensive structure-preserving encodings such as XML or HTML are unnecessary and can even hurt accuracy.
- The number of retrieved segments has a sweet spot: R@3 outperforms R@1, R@5, and R@7 on FINE, so retrieval quantity should be tuned rather than maximized.
- Keyword completion with document context (company and time) materially improves extraction, raising average accuracy from 0.3922 with the bare keyword to 0.6993 with full context.
- A single well-designed few-shot example gives better accuracy than zero-shot or multiple shots, indicating that prompt consistency matters more than example count.
Reading between the lines
- If embedding retrieval is the bottleneck, then better embeddings for table-heavy text, or hybrid retrieval that also uses table structure, should directly raise extraction accuracy within the same pipeline.
- The R@3 optimum found on FINE may not transfer to other genres; a production version could select the number of retrieved segments per query based on retrieval confidence rather than a global constant.
- The framework's modularity suggests it could be applied to legal, medical, or scientific records, but the paper demonstrates only finance, Wikipedia, and materials-science domains, so cross-domain generality remains an open extension.
- The plain-serialization result hints that LLMs may understand tables through token co-occurrence between headers and values rather than through structural nesting, which could be probed by shuffling table layout while keeping content identical.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper proposes AIE, a four-module framework (Segmentation, Retrieval, Summarization, Extraction) for enabling LLMs to perform information extraction from hybrid long documents (HLDs) that exceed the LLM token limit. It introduces FINE, a new dataset of financial key performance indicators extracted from SEC filings, and evaluates AIE against a 'naive' LLM-based approach on FINE, WIKIR, and MPP. The experiments show large improvements for AIE on FINE (63.89% vs 13.92% at RETA 1% with GPT-3.5) and analyze several design choices: table serialization formats, number of retrieved segments, summarization strategies, numerical precision prompts, keyword completion, and few-shot counts. The paper concludes that a retrieve-summarize-extract pipeline with plain-table serialization and refine summarization is effective for HLD information extraction.
Significance. If the results are reproducible, the AIE framework offers a practical recipe for LLM-based extraction from long, mixed text-table documents, and the FINE dataset is a valuable new resource for the community. The paper also provides a useful systematic comparison of multiple design decisions, including table serialization, retrieval granularity, and prompt engineering. The main claims are concrete and testable, and the dataset/code release is a positive feature. However, the significance is currently tempered by two methodological issues: an undefined baseline and test-set-driven configuration selection, both of which affect the credibility of the quantitative claims.
major comments (2)
- [Section IV, Figures 2–4] The 'naive LLM-based approach' is never defined. Please specify exactly how the naive method processes an HLD: whether the document is truncated, how tables are serialized, which prompt is used for extraction, whether the same extraction module is used, and how the final answer is produced. Without this definition, the comparison in Figures 2–4 and the central claim that 'AIE consistently outperforms the naive method' are not interpretable or reproducible.
- [Section IV, Tables II–VII] The final AIE configuration is selected by running all variants on the FINE test set and picking the winner in each dimension (R@3 in Table III, PLAIN in Table II, Refine in Table IV, TD-RSP in Table V, KTC in Table VI, 1-shot in Table VII). The headline AIE accuracy in Figure 2 is then reported under this configuration. This is test-set selection, so the reported numbers are upper bounds rather than unbiased estimates of performance. Please enforce a validation split (or cross-validation) for model selection and report the chosen configuration's accuracy on a held-out test set, or at least discuss the magnitude of the selection effect.
minor comments (7)
- [Abstract] The phrase 'The naive AIE has adaptability in many complex scenarios' appears to be a typo; it should likely read 'The AIE has adaptability' or 'The proposed AIE is adaptable.'
- [Section III] The RETA metric is described only verbally. Please provide the explicit formula and specify how predictions with missing or non-numeric outputs are scored.
- [Figure 2] The y-axis label 'Average Accuracy' is confusing because the x-axis already shows RETA levels. Clarify that the bars represent the average accuracy over all queries at the corresponding RETA threshold.
- [Figure 4] The heatmaps lack a legend and a clear description of the color scale. Add a legend and explain what the colors represent for the RPD values.
- [Section I and Section VI] The paper states that the dataset and code are 'publicly available in the attachments,' but no link or repository identifier is provided. Include a working URL for reproducibility.
- [Section IV] No variance or significance tests are reported for any of the comparisons. Given the large margins this is not fatal, but including error bars or a significance test for the headline FINE result would strengthen the claim.
- [Table I] For the FINE dataset, please also report the number of documents and the number of queries, not only token length statistics, so readers can gauge the dataset size.
Circularity Check
The headline AIE comparison is reported under a configuration whose components (PLAIN, R@3, Refine, TD-RSP, KTC, 1-shot) were each selected as the best performer on the same FINE test set, so the central 'consistent outperformance' claim is an in-sample selection result rather than an independent prediction.
-
fitted input called prediction
[Section I, final paragraph; Section IV, Tables II-VII and Figure 2]
"The subsequent sections detail the AIE framework, incorporating globally optimal settings determined through our analysis (Section II). ... R@3 achieves the highest accuracy across all RETA levels. ... the 1-shot setting achieves the highest accuracy across all RETA levels."
The final AIE pipeline is assembled from the winners of a model-selection sweep on the same FINE test set: PLAIN in Table II, R@3 in Table III, Refine in Table IV, TD-RSP in Table V, KTC in Table VI, and 1-shot in Table VII. The headline accuracy (Figure 2a, 63.89% at RETA 1%) is then computed on that same test set with that selected configuration. The 'consistent outperformance' claim therefore does not test a fixed a-priori framework; it reports the performance of the best configuration on the data used to pick the configuration. The reported margins are upper bounds, and the conclusion is partly forced by the selection procedure rather than derived from an independent prediction.
full rationale
The core derivation chain (segment, retrieve by SentenceTransformer similarity, summarize, extract) is self-contained and is not definitionally tied to the target values; the FINE dataset is new and externally grounded in SEC filings, and the WIKIR/MPP evaluations provide some held-out evidence with settings fixed from FINE. However, the paper's main quantitative claim about AIE's superiority is weakened by in-sample configuration selection: every component of the reported AIE is chosen because it maximized accuracy on the same FINE test set that produces the headline numbers. This is the 'fitted input called prediction' pattern, not a definitional equivalence, so the score is partial (6) rather than total. The undefined 'naive' baseline is a reproducibility problem but not a circularity, and the self-citation [5] is not load-bearing for the derivation chain.
Assumptions & free parameters
free parameters (6)
- Retrieval segment count K =
3 (R@3)
- Table serialization format =
PLAIN
- Summarization strategy =
Refine
- Numerical precision prompt =
TD-RSP
- Keyword completion context =
KTC (keyword+time+company)
- Number of shots =
1
assumptions (5)
- domain assumption Embedding similarity between the keyword and document segments reliably locates segments containing the target value.
- domain assumption Financial reports from SEC EDGAR contain a single correct numeric value for each keyword-document pair.
- domain assumption LLM extraction from a generated summary does not introduce systematic hallucination that dominates the measured errors.
- domain assumption The 'naive' baseline is a fair representation of direct LLM-based extraction without the AIE pipeline.
- standard math Cosine similarity as used in Sentence-BERT is an appropriate relevance metric.
Cite this review
Pith. "Pith review of Extract Information from Hybrid Long Documents Leveraging LLMs: A Framework and Dataset." pith.science (2026). https://pith.science/paper/NOEH3LWE
@misc{pith2026241220072,
author = {Pith},
title = {Pith review of: Extract Information from Hybrid Long Documents Leveraging LLMs: A Framework and Dataset},
year = {2026},
howpublished = {\url{https://pith.science/paper/NOEH3LWE}},
note = {Machine review of arXiv:2412.20072}
}
read the original abstract
Large Language Models (LLMs) demonstrate exceptional performance in textual understanding and tabular reasoning tasks. However, their ability to comprehend and analyze hybrid text, containing textual and tabular data, remains unexplored. The hybrid text often appears in the form of hybrid long documents (HLDs), which far exceed the token limit of LLMs. Consequently, we apply an Automated Information Extraction framework (AIE) to enable LLMs to process the HLDs and carry out experiments to analyse four important aspects of information extraction from HLDs. Given the findings: 1) The effective way to select and summarize the useful part of a HLD. 2) An easy table serialization way is enough for LLMs to understand tables. 3) The naive AIE has adaptability in many complex scenarios. 4) The useful prompt engineering to enhance LLMs on HLDs. To address the issue of dataset scarcity in HLDs and support future work, we also propose the Financial Reports Numerical Extraction (FINE) dataset. The dataset and code are publicly available in the attachments.
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