Grounding natural language with autonomous interaction

The resurgence of deep neural networks has resulted in impressive advances in natural language processing (NLP). This success, however, is contingent on access to large amounts of structured supervision, often manually constructed and unavailable for many applications and domains. In this thesis, I present novel computational models that integrate reinforcement learning with language understanding to induce grounded representations of semantics. Using unstructured feedback, these techniques not only enable task-optimized representations which reduce dependence on high quality annotations, but also exploit language in adapting control policies across different environments. First, I describe an approach for learning to play text-based games, where all interaction is through natural language and the only source of feedback is in-game rewards. Employing a deep reinforcement learning framework to jointly learn state representations and action policies, our model outperforms several baselines on different domains, demonstrating the importance of learning expressive representations. Second, I exhibit a framework for utilizing textual descriptions to tackle the challenging problem of cross-domain policy transfer for reinforcement learning (RL). We employ a model-based RL approach consisting of a differentiable planning module, a model-free component and a factorized state representation to effectively make use of text. Our model outperforms prior work on both transfer and multi-task scenarios in a variety of different environments. Finally, I demonstrate how reinforcement learning can enhance traditional NLP systems in low resource scenarios. In particular, I describe an autonomous agent that can learn to acquire and integrate external information to enhance information extraction. Our experiments on two databases - shooting incidents and food adulteration cases - demonstrate that our system significantly improves over traditional extractors and a competitive meta-classifier baseline.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2017

Author dc:creator

• Narasimhan, Karthik Rajagopal

Advisor dc:contributor.advisor

• Regina Barzilay.

• Electrical Engineering and Computer Science.

Statement dc:rights

• MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/114003

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/114003