Semantic Parsing on Freebase from Question-Answer Pairs
Jonathan BerantAndrew ChouRoy FrostigPercy Liang
Proposes a scalable semantic parser that learns to query large-scale knowledge bases like Freebase using only question-answer pairs by combining text-to-predicate alignment with a novel bridging operation over neighboring predicates.
Building automated systems that answer natural language questions by querying massive databases is essential for modern search and information retrieval. Traditional semantic parsing methods translate questions into executable computer queries but rely on expensive, expert-annotated formal logic and are restricted to narrow domains. Scaling these systems to large-scale knowledge repositories like Freebase, which contains tens of millions of entities and thousands of properties, creates a major bottleneck because the space of potential query interpretations expands exponentially.
The article demonstrates that a semantic parser can successfully scale to large-scale databases by training exclusively on question-answer pairs rather than expensive logical annotations. It aims to establish that combining text alignment with automated logical bridging allows systems to resolve complex natural language queries accurately across open domains.
To achieve this, the authors developed a system named SEMPRE. The approach generates candidate query operations using two mechanisms: a coarse mapping built by aligning text patterns from 15 million web assertions to database properties, and a novel bridging technique that infers missing relations based on compatibility with adjacent elements. The system filters candidate queries using a statistical model powered by syntactic cues and answer characteristics. The framework was evaluated on the established FREE917 benchmark of 917 questions and on WEBQUESTIONS, a new and realistic open-domain dataset of 5,810 web-mined questions collected via crowdsourcing.
The findings show that training without expert logic annotations can match or surpass supervised methods. On the FREE917 benchmark, the proposed system achieved 62% accuracy, outperforming the previous state of the art at 59% despite having no access to annotated logical structures during training. On the challenging WEBQUESTIONS dataset, the system achieved 31.4% accuracy, representing an absolute improvement of 4.5 percentage points over the natural baseline of 26.9%. Feature analysis confirmed that combining text-based lexicon alignment with bridging was crucial, as bridging captured rare and implicit relations that text alignment alone missed, while denotation and part-of-speech features substantially reduced parsing errors.
These results indicate that automated question-answering systems can be developed and scaled at significantly lower costs by crowdsourcing simple question-answer pairs instead of employing scarce linguistic experts. By eliminating rigid formal rule construction, organizations can deploy broader search capabilities over complex business and public databases with reduced annotation overhead.
To build on this framework, future engineering efforts should focus on improving entity disambiguation across large inventories and handling complex, multi-clause linguistic structures. Incorporating methods that automatically learn composite database predicates from data is recommended to capture more nuanced language. Decision-makers should maintain moderate confidence in these findings, noting that while performance on curated benchmarks is strong, accuracy on noisy, open-ended web questions remains around 31.4% due to entity recognition ambiguity and partial crowdsourced answers.
- Paper: Distant supervision for relation extraction without labeled data, Mike D. Mintz et al. (2009). Reading this distant supervision work first clarifies how large knowledge bases like Freebase can be leveraged automatically to extract training data for semantic parsers.
- Paper: Learning to Map Sentences to Logical Form: Structured Classification with Probabilistic Categorial Grammars, Luke S. Zettlemoyer et al. (2005). This foundational paper on mapping sentences to logical forms without manual tree annotations provides the primary semantic parsing methodology built upon by the source.
- Paper: YAGO: A Core of Semantic Knowledge Unifying WordNet and Wikipedia, Fabian M. Suchanek et al. (2007). Understanding the structure and integration of WordNet and Wikipedia in YAGO provides vital background on the core semantic knowledge bases utilized in large-scale parsing.
- Paper: TriviaQA: A Large Scale Distantly Supervised Challenge Dataset for Reading Comprehension, Mandar Joshi et al. (2017). This benchmark extends open-domain question-answering research by introducing distantly supervised challenge datasets built from natural questions and web search results.
- Paper: Reading Wikipedia to Answer Open-Domain Questions, Danqi Chen et al. (2017). This work builds directly upon open-domain question answering techniques by presenting DrQA for reading Wikipedia to answer factual queries.
- Paper: Dense Passage Retrieval for Open-Domain Question Answering, Vladimir Karpukhin et al. (2020). This paper advances open-domain question answering by replacing sparse retrieval with dense passage retrieval methods trained on question-answer pairs.
