An extended GHKM algorithm for inducing λ-SCFG

Abstract

Semantic parsing, which aims at mapping a natural language (NL) sentence into its formal meaning representation (e.g., logical form), has received increasing attention in recent years. While synchronous context-free grammar (SCFG) augmented with lambda calculus (λ- SCFG) provides an effective mechanism for semantic parsing, how to learn such λ- SCFG rules still remains a challenge because of the difficulty in determining the correspondence between NL sentences and logical forms. To alleviate this structural divergence problem, we extend the GHKM algorithm, which is a state-ofthe- art algorithm for learning synchronous grammars in statistical machine translation, to induce λ- SCFG from pairs of NL sentences and logical forms. By treating logical forms as trees, we reformulate the theory behind GHKM that gives formal semantics to the alignment between NL words and logical form tokens. Experiments on the GEOQUERY dataset show that our semantic parser achieves an F-measure of 90:2%, the best result published to date. Copyright © 2013, Association for the Advancement of Artificial Intelligence (www.aaai.org). All rights reserved.