Evelyne Viegas

From Submit to Submitted via Submission: On Lexical Rules in Large-Scale Lexicon Acquisition

This paper deals with the discovery, representation, and use of lexical rules (LRs) during large-scale semi-automatic computational lexicon acquisition. The analysis is based on a set of LRs implemented and tested on the basis of Spanish and English business- and finance-related corpora. We show that, though the use of LRs is justified, they do not come cost-free. Semi-automatic output checking is required, even with blocking and preemtion procedures built in. Nevertheless, large-scope LRs are justified because they facilitate the unavoidable process of large-scale semi-automatic lexical acquisition. We also argue that the place of LRs in the computational process is a complex issue.

Semantics in Action

The paper presents a concise description of a comprehensive approach to computational lexical semantics and focuses on the treatment of events. We reason about the semantic information that should be encoded in a lexicon entry to support the twin tasks of constructing Text Meaning Representations (TMRs) for input texts and generating texts off TMRs. As static knowledge sources cannot be expected to cover all textual inputs, we describe and illustrate how lexical entries can be changed dynamically to fit the textual context at processing time. On the very important issue of knowledge acquisition, our experience shows that determining the meaning of lexical items is not a trivial task for a team of human acquirers (who are, we believe, absolutely indispensable for the more complex decisions in lexical knowledge acquisition). We illustrate how one can overcome the subjectivity of acquirers partly through advanced methodology and partly by having the lexical-semantic model account for some of the combinatory and (semi-)productive principles of natural language.

The Computational Lexical Semantics of Syntagmatic Expressions

In this paper, we address the issue of syntagmatic expressions from a computational lexical semantic perspective. From a representational viewpoint, we argue for a hybrid approach combining linguistic and conceptual paradigms, in order to account for the continuum we find in natural languages from free combining words to frozen expressions. In particular, we focus on the place of lexical and semantic restricted co-occurrences. From a processing viewpoint, we show how to generate/analyze syntagmatic expressions by using an efficient constraintbased processor, well fitted for a knowledge-driven approach.

Opening the World with Active Words and Concept Triggers

In this paper we present a proposal to help bypass the bottleneck of knowledge-based NLP systems having to work under a closed world assumption. We propose ways of reinterpreting static sources as active ones, by allowing a system to create new lexical entries on the fly, and investigate how to create new concepts on the fly. We argue that a computational lexical semantic approach is a sine qua non to work under an open world assumption. More specifically, we show how to create new lexicon entries using lexico-semantic rules and investigate how to create new concepts for unknown words, building a new model to trigger concepts in context.

A Comparison of Different Lexical Semantics Approaches for Transfer Verbs with a Particular Emphasis on Buy/Sell

In this paper, are discussed and compared different approaches to lexical semantics, reflecting presentations during the panel discussion at the Workshop on Predicative Forms in Natural Language. The panel was organized with the aim of evaluating different approaches to the study of word meaning, by comparing their advantages and disadvantages from both a theoretical and an applied perspective. The verb pair buy and sell was taken to support comparisons. The following areas are surveyed: WordNet and the organization of verbs of possession, the Lexical Conceptual Structure, The Generative Lexicon, an integrated view adopted e.g. in Mikrokosmos and a psycho-linguistics perspective.