Human-in-the-Loop Question Answering with Natural Language Interaction
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Generalizing beyond the training examples is the primary goal of machine learning. In natural language processing (NLP), impressive models struggle to generalize when faced with test examples that differ from the training examples: e.g., in genre, domain, or language. I study interactive methods that overcome such limitations by seeking feedback from human users to successfully complete the task at hand and improve over time while on the job. Unlike previous work that adopts simple forms of feedback (e.g., labeling predictions as correct/wrong or answering yes/no clarification questions), I focus on using free-form natural language as the communication interface for providing feedback which can convey richer information and offer a more flexible interaction.
An essential skill that language-based interactive systems should have is to understand user utterances in conversational contexts. I study conversational question answering (CQA) in which humans interact with a question answering (QA) system by asking a sequence of related questions. CQA requires models to link questions together to resolve the conversational dependencies between them such as coreference and ellipsis. I introduce question-in-context rewriting to reduce context-dependent conversational questions to independent stand-alone questions that can be answered with existing QA models. I collect a large dataset of human rewrites and I use it to evaluate a set of models for the question rewriting task.
Next, I study semantic parsing in interactive settings in which users correct parsing errors using natural language feedback. Most existing work frames semantic parsing as a one-shot mapping task. I establish that the majority of parsing mistakes that recent neural text-to-SQL parsers make are minor. Hence, it is often feasible for humans to detect and suggest corrections for such mistakes if they have the opportunity to provide precise feedback. I describe an interactive text-to-SQL parsing system that enables users to inspect the inferred parses and correct any errors they find by providing feedback in free-form natural language. I construct SPLASH: a large dataset of SQL correction instances paired with a diverse set of human-authored natural language feedback utterances. Using SPLASH, I posed a new task: given a question paired with an initial erroneous SQL parse, to what extent can we correct the parse based on a provided natural language feedback?
Then, I present NL-EDIT: a neural model for the correction task. NL-EDIT combines two key ideas: 1) interpreting the feedback in the context of the other elements of the interaction and, 2) explicitly generating edit operations to correct the initial query instead of re-generating the full query from scratch. I create a simple SQL editing language whose basic units are add/delete operations applied to different SQL clauses. I discuss evaluation methods that help understand the usefulness and limitations of semantic parse correction models.
I conclude this thesis by identifying three broad research directions for further advancing collaborative human-computer NLP: (1) developing user-centered explanations, (2) designing and evaluating interaction mechanisms, and (3) learning from interactions.