Abstract | We devise a gold-standard sense- and parse tree-annotated dataset based on the intersection of the Penn Treebank and SemCor, and experiment with different approaches to both semantic representation and disambiguation. |
Experimental setting | Below, we outline the dataset used in this research and the parser evaluation methodology, explain the methodology used to perform PP attachment, present the different options for semantic representation , and finally detail the disambiguation methods. |
Experimental setting | The gold-standard sense annotations allow us to perform upper bound evaluation of the relative impact of a given semantic representation on parsing and PP attachment performance, to contrast with the performance in more realistic semantic disambiguation settings. |
Experimental setting | 4.3 Semantic representation |
Integrating Semantics into Parsing | There are three main aspects that we have to consider in this process: (i) the semantic representation , (ii) semantic disambiguation, and (iii) morphology. |
Integrating Semantics into Parsing | The more fine-grained our semantic representation , the higher the average polysemy and the greater the need to distinguish between these senses. |
Introduction | We explore several models for semantic representation , based around WordNet (Fellbaum, 1998). |
Introduction | In experimenting with different semantic representations , we require some strategy to disambiguate the semantic class of polysemous words in context (e. g. determining for each instance of crane whether it refers to an animal or a lifting device). |
Abstract | Despite large typological differences between Wambaya and the languages on which the development of the resource was based, the Grammar Matrix is found to provide a significant jump-start in the creation of the grammar for Wambaya: With less than 5.5 person-weeks of development, the Wambaya grammar was able to assign correct semantic representations to 76% of the sentences in a naturally occurring text. |
Background | The core type hierarchy defines the basic feature geometry, the ways that heads combine with arguments and adjuncts, linking types for relating syntactic to semantic arguments, and the constraints required to compositionally build up semantic representations in the format of Minimal Recursion Semantics (Copestake et al., 2005; Flickinger and Bender, 2003). |
Background | To relate such discontinuous noun phrases to appropriate semantic representations where ‘having- |
Wambaya grammar | The linguistic analyses encoded in the grammar serve to map the surface strings to semantic representations (in Minimal Recursion Semantics (MRS) format (Copestake et al., 2005)). |
Wambaya grammar | This section has presented the Matrix-derived grammar of Wambaya, illustrating its semantic representations and analyses and measuring its performance against held-out data. |
Abstract | We call this approach hypertagging, as it operates at a level “above” the syntax, tagging semantic representations with syntactic lexical categories. |
Background | This process involves converting the corpus to reflect more precise analyses, Where feasible, and adding semantic representations to the lexical categories. |
Conclusion | We have introduced a novel type of supertagger, which we have dubbed a hypertagger, that assigns CCG category labels to elementary predications in a structured semantic representation with high accuracy at several levels of tagging ambiguity in a fashion reminiscent of (Bangalore and Rambow, 2000). |
Introduction | We have dubbed this approach hypertagging, as it operates at a level “above” the syntax, moving from semantic representations to syntactic categories. |
Results and Discussion | As the effort to engineer a grammar suitable for realization from the CCGbank proceeds in parallel to our work on hypertagging, we expect the hypertagger-seeded realizer to continue to improve, since a more complete and precise extracted grammar should enable more complete realizations to be found, and richer semantic representations should |
Expressive completeness and redundancy elimination | Koller and Thater (2006) define semantic equivalence in terms of a rewrite system that specifies under what conditions two quantifiers may exchange their positions without changing the meaning of the semantic representation . |
Expressive completeness and redundancy elimination | Expressions of natural language itself are (extremely underspecified) descriptions of sets of semantic representations , and so Ebert’s argument applies to NL expressions as well. |
Introduction | In the past few years, a “standard model” of scope underspecification has emerged: A range of formalisms from Underspecified DRT (Reyle, 1993) to dominance graphs (Althaus et al., 2003) have offered mechanisms to specify the “semantic material” of which the semantic representations are built up, plus dominance or outscoping relations between these building blocks. |
Regular tree grammars | We can now use regular tree grammars in underspecification by representing the semantic representations as trees and taking an RTG G as an underspecified description of the trees in L(G). |