While there has been significant recent work on learning semantic parsers for specific task/ domains, the results don't transfer from one domain to another domains. We describe a project to learn a broad-coverage semantic lexicon for domain independent semantic parsing. The technique involves several bootstrapping steps starting from a semantic parser based on a modest-sized hand-built semantic lexicon. We demonstrate that the approach shows promise in building a semantic lexicon on the scale of WordNet, with more coverage and detail that currently available in widely-used resources such as VerbNet. We view having such a lexicon as a necessary prerequisite for any attempt at attaining broad-coverage semantic parsing in any domain. The approach we described applies to all word classes, but in this paper we focus here on verbs, which are the most critical phenomena facing semantic parsing.
Introduction and MotivationRecently we have seen an explosion of work on learning semantic parsers (e.g., Matuszek, et al, 2012;Tellex et al, 2013; Branavan et al, 2010, Chen et al, 2011). While such work shows promise, the results are highly domain dependent and useful only for that domain. One cannot, for instance, reuse a lexical entry learned in one robotic domain in another robotic domain, let alone in a database query domain. Furthermore, the techniques being developed require domains that are simple enough so that the semantic models can be produced, either by hand or induced from the application. Language in general, however, involves much more complex concepts and connections, including discussion of involves abstract concepts, such as plans, theories, political views, and so on. It is not clear how the techniques currently being developed could be generalized to such language.The challenge we are addressing is learning a broad-coverage, domain-independent semantic parser, i.e., a semantic parser that can be used in any domain. At present, there is a tradeoff between the depth of semantic representation produced and the coverage of the techniques. One of the critical gaps in enabling more general, deeper semantic systems is the lack of any broadcoverage deep semantic lexicon. Such a lexicon must contain at least the following information: i. an enumeration of the set of distinct senses for the word (e.g., as in WordNet, PropBank), linked into an ontology that supports reasoning ii. For each sense, we would have• Deep argument structure, i.e., semantic roles with selectional preferences • Constructions that map syntax to the deep argument structure (a.k.a. linking rules) • Lexical entailments that characterize the temporal consequences of the event described by the verb The closest example to such lexical entries can be found in VerbNet (Kipper et al, 2008), a handbuilt resource widely used for a range of general applications. An example entry from VerbNet is seen in Figure 1, which describes a class of verbs called murder-42.1. VerbNet clusters verbs by the constructions they take, not by sense or meaning, alt...