Attention-Based Bidirectional Long Short-Term Memory Networks for Relation Classification
Written for the Research library (claude-opus-5-5) from the paper text. Original — aclanthology.org/P16-2034.pdf
Summary
This paper addresses relation classification: deciding which semantic relation holds between two marked nominals in a sentence. Earlier strong systems depended on handcrafted or externally derived features such as WordNet, dependency parses, POS tags and NER output. These features are costly to produce, can introduce errors and may generalize poorly. The authors propose Att-BLSTM. Each word, including the entity position markers, is mapped to an embedding and encoded by a bidirectional LSTM with peephole connections. An attention layer then learns a weight for every time step and pools the word-level states into one sentence vector, which a softmax classifier labels. Dropout and L2 constraints regularize training. On the SemEval-2010 Task 8 benchmark, the model reaches a macro-F1 of 84.0% using only word vectors. That result beats most prior systems and nearly matches a feature-rich BLSTM. The work matters because it shows that attention lets a simple, resource-free model find the decisive words wherever they occur in a sentence. This makes the approach attractive for languages with few NLP tools.
Key points
- Data: SemEval-2010 Task 8 has 9 directed relation types plus an undirected Other class. It contains 10,717 sentences, split into 8,000 for training and 2,717 for testing. Because no official development set exists, 800 training sentences were held out for validation.
- Input: The entity markers ⟨e1⟩, ⟨/e1⟩, ⟨e2⟩, ⟨/e2⟩ are treated as ordinary tokens. The model uses no POS, NER, dependency or WordNet features. Forward and backward LSTM outputs are combined by element-wise sum.
- Results: Att-BLSTM scores 84.0% F1 with 100-dimensional GloVe vectors (Pennington et al., 2014). It scores 82.5% with 50-dimensional Turian et al. (2010) vectors, about 2.5 points above the bidirectional RNN of Zhang and Wang (2015) with the same embeddings.
- Baselines: The best SemEval-2010 SVM reached 82.2%, the CNN of Zeng et al. (2014) 82.7% and SDP-LSTM 83.7%. The feature-heavy BLSTM of Zhang et al. (2015) performs similarly to Att-BLSTM but is far more complex.
- Training setup: The model uses AdaDelta with learning rate 1.0, minibatch size 10 and L2 strength 10⁻⁵. Dropout rates are 0.3 on embeddings, 0.3 on the LSTM layer and 0.5 on the penultimate layer.
Cited by
Cite
@inproceedings{zhou2016attention,
title = {{Attention-Based Bidirectional Long Short-Term Memory Networks for Relation Classification}},
author = {Zhou, Peng and Shi, Wei and Tian, Jun and Qi, Zhenyu and Li, Bingchen and Hao, Hongwei and Xu, Bo},
booktitle = {Proceedings of the 54th Annual Meeting of the Association for Computational Linguistics (Volume 2: Short Papers)},
year = {2016},
doi = {10.18653/v1/p16-2034},
url = {https://doi.org/10.18653/v1/p16-2034}
}References
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