Vivek Srikumar
2020
INFOTABS: Inference on Tables as Semi-structured Data
Vivek Gupta
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Maitrey Mehta
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Pegah Nokhiz
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Vivek Srikumar
Proceedings of the 58th Annual Meeting of the Association for Computational Linguistics
In this paper, we observe that semi-structured tabulated text is ubiquitous; understanding them requires not only comprehending the meaning of text fragments, but also implicit relationships between them. We argue that such data can prove as a testing ground for understanding how we reason about information. To study this, we introduce a new dataset called INFOTABS, comprising of human-written textual hypotheses based on premises that are tables extracted from Wikipedia info-boxes. Our analysis shows that the semi-structured, multi-domain and heterogeneous nature of the premises admits complex, multi-faceted reasoning. Experiments reveal that, while human annotators agree on the relationships between a table-hypothesis pair, several standard modeling strategies are unsuccessful at the task, suggesting that reasoning about tables can pose a difficult modeling challenge.
Learning Constraints for Structured Prediction Using Rectifier Networks
Xingyuan Pan
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Maitrey Mehta
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Vivek Srikumar
Proceedings of the 58th Annual Meeting of the Association for Computational Linguistics
Various natural language processing tasks are structured prediction problems where outputs are constructed with multiple interdependent decisions. Past work has shown that domain knowledge, framed as constraints over the output space, can help improve predictive accuracy. However, designing good constraints often relies on domain expertise. In this paper, we study the problem of learning such constraints. We frame the problem as that of training a two-layer rectifier network to identify valid structures or substructures, and show a construction for converting a trained network into a system of linear constraints over the inference variables. Our experiments on several NLP tasks show that the learned constraints can improve the prediction accuracy, especially when the number of training examples is small.
Structured Tuning for Semantic Role Labeling
Tao Li
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Parth Anand Jawale
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Martha Palmer
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Vivek Srikumar
Proceedings of the 58th Annual Meeting of the Association for Computational Linguistics
Recent neural network-driven semantic role labeling (SRL) systems have shown impressive improvements in F1 scores. These improvements are due to expressive input representations, which, at least at the surface, are orthogonal to knowledge-rich constrained decoding mechanisms that helped linear SRL models. Introducing the benefits of structure to inform neural models presents a methodological challenge. In this paper, we present a structured tuning framework to improve models using softened constraints only at training time. Our framework leverages the expressiveness of neural networks and provides supervision with structured loss components. We start with a strong baseline (RoBERTa) to validate the impact of our approach, and show that our framework outperforms the baseline by learning to comply with declarative constraints. Additionally, our experiments with smaller training sizes show that we can achieve consistent improvements under low-resource scenarios.
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Co-authors
- Maitrey Mehta 2
- Vivek Gupta 1
- Pegah Nokhiz 1
- Xingyuan Pan 1
- Tao Li 1
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- ACL3