From Surface Dependencies towards Deeper Semantic Representations
نویسندگان
چکیده
In the past, a divide could be seen between ’deep’ parsers on the one hand, which construct a semantic representation out of their input, but usually have significant coverage problems, and more robust parsers on the other hand, which are usually based on a (statistical) model derived from a treebank and have larger coverage, but leave the problem of semantic interpretation to the user. More recently, approaches have emerged that combine the robustness of datadriven (statistical) models with more detailed linguistic interpretation such that the output could be used for deeper semantic analysis. Cahill et al. (2002) use a PCFG-based parsing model in combination with a set of principles and heuristics to derive functional (f-)structures of Lexical-Functional Grammar (LFG). They show that the derived functional structures have a better quality than those generated by a parser based on a state-of-the-art hand-crafted LFG grammar. Advocates of Dependency Grammar usually point out that dependencies already are a semantically meaningful representation (cf. Menzel, 2003). However, parsers based on dependency grammar normally create underspecified representations with respect to certain phenomena such as coordination, apposition and control structures. In these areas they are too ’shallow’ to be directly used for semantic interpretation. In this paper, we adopt a similar approach to Cahill et al. (2002) using a dependency-based analysis to derive functional structure, and demonstrate the feasibility of this approach using German data. A major focus of our discussion is on the treatment of coordination and other potentially underspecified structures of the dependency data input. F-structure is one of the two core levels of syntactic representation in LFG1 (Bresnan, 2001). Independently of surface order, it encodes abstract syntactic functions that constitute predicate argument structure and other dependency relations such as subject, predicate, adjunct, but also further semantic information such as
منابع مشابه
On deriving semantic representations from dependencies: A Practical approach for evaluating meaning in learner corpora
One of the reasons for the popularity of dependency approaches in recent computational linguistics is their ability to efficiently derive the core functorargument structure of a sentence as an interface to semantic interpretation. Exploring this feature of dependency structures further, in this paper we show how basic dependency representations can be mapped to semantic representation as used i...
متن کاملApplying Robust Semantics
Semantic representations provide an abstraction which allows generalisations to be made across very different surface forms and different syntactic formalisms. But deriving conventional semantic representations requires more information than can be extracted from morphology and syntax, even by deep grammars. The standard way of dealing with this is to use underspecified semantic representations...
متن کامل10 th Conference of the Pacific Association for Computational
Semantic representations provide an abstraction which allows generalisations to be made across very different surface forms and different syntactic formalisms. But deriving conventional semantic representations requires more information than can be extracted from morphology and syntax, even by deep grammars. The standard way of dealing with this is to use underspecified semantic representations...
متن کاملLearning Semantic Representations in a Bigram Language Model
This paper investigates the extraction of semantic representations from bigrams. The major obstacle to this objective is that while these word to word dependencies do contain a semantic component, other factors, e.g. syntax, play a much stronger role. An effective solution will therefore require some means of isolating semantic structure from the remainder. Here, the possibility of modelling se...
متن کاملEnglish Resource Semantics
Recent years have seen a dramatic increase in interest in semanticallyinformed natural language processing, including parsing into semantic representations, grounded language processing that connects linguistic structures to world representations, proposals to integrate compositional and distributional approaches to semantics, and approaches to semanticallysensitive tasks including sentiment ...
متن کامل