Machine Comprehension Using Match-LSTM and Answer Pointer
Written for the Research library (claude-opus-5-5) from the paper text, in our own words: the license "arXiv — non-exclusive license to distribute" does not allow redistributing the text itself. Original — arxiv.org/pdf/1608.07905
Summary
The paper addresses extractive reading comprehension on SQuAD, a crowdsourced dataset of Wikipedia paragraphs where an answer can be any span of the passage. Earlier end-to-end neural readers either chose among given candidates or returned a single token, so they did not fit this setting. The authors propose a fully neural system with three stages:
- Encoding: LSTMs encode the passage and the question.
- Matching: a bidirectional match-LSTM, taken from their earlier textual entailment work, reads the passage while attending over the question. The question plays the premise and the passage the hypothesis.
- Answer Pointer: a layer built on Pointer Net (Vinyals et al., 2015) outputs positions in the passage rather than words from a vocabulary.
They compare two decoders. A sequence model emits answer positions one by one, and a boundary model predicts only the start and end, optionally with an added span search. The best reported test result is 67.9% exact match and 77.0% F1. This clearly beats the feature-engineered baseline of Rajpurkar et al. (2016) and comes close to the leading system of the time. It shows that answer spans can be learned end to end without hand-built linguistic pipelines.
Key points
- Architecture: LSTM preprocessing layer, then a bidirectional match-LSTM layer, then an Answer Pointer (Ans-Ptr) layer. The two proposed models differ only in the final layer: the sequence model allows non-contiguous positions, while the boundary model predicts start and end indices.
- Test results: the best system reaches 67.9% EM and 77.0% F1 on the hidden SQuAD test set, and the introduction notes that an ensemble boosts results. The conclusion credits the boundary model with 67.6% EM and 77% F1, so the paper's own figures differ slightly.
- Comparison:
- Both models outperform the logistic regression baseline with manual features from Rajpurkar et al. (2016).
- The boundary model beats the sequence model.
- The state of the art at the time (Salesforce Research) was 71.6% EM and 80.4% F1.
- Analysis: performance is broken down by answer length and question type. "Why" questions remain weak and are flagged for future work.
- Code: released on GitHub as SeqMatchSeq (shuohangwang/SeqMatchSeq).
Cited by
- Simple and Effective Multi-Paragraph Reading Comprehension
- DuReader: a Chinese Machine Reading Comprehension Dataset from Real-world Applications
- Shakespearizing Modern Language Using Copy-Enriched Sequence to Sequence Models
- Adversarial Examples for Evaluating Reading Comprehension Systems
- The NarrativeQA Reading Comprehension Challenge
- A Unified MRC Framework for Named Entity Recognition
- Learned in Translation: Contextualized Word Vectors
- The Natural Language Decathlon: Multitask Learning as Question Answering
- SQuAD: 100,000+ Questions for Machine Comprehension of Text
- Bidirectional Attention Flow for Machine Comprehension
- Dynamic Coattention Networks For Question Answering
- QANet: Combining Local Convolution with Global Self-Attention for Reading Comprehension
- QMSum: A New Benchmark for Query-based Multi-domain Meeting Summarization
Cite
@misc{wang2016machine,
title = {{Machine Comprehension Using Match-LSTM and Answer Pointer}},
author = {Wang, Shuohang and Jiang, Jing},
year = {2016},
doi = {10.48550/arxiv.1608.07905},
eprint = {1608.07905},
archivePrefix = {arXiv},
url = {https://doi.org/10.48550/arxiv.1608.07905}
}References
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