Resolving Shell Nouns
Varada Kolhatkar, Graeme Hirst · 2014
Shell nouns are abstract nouns, such as fact, issue, idea, and problem, which, among other functions, facilitate efficiency by avoiding repetition of long stretches of text.An example is shown in (1).Shell nouns encapsulate propositional content, and the process of identifying this content is referred to as shell noun resolution.(1) Living expenses are much lower in rural India than in New York, but this fact is not fully captured if prices are converted with currency exchange rates.This dissertation presents the first computational work on resolving shell nouns.The research is guided by three primary questions: first, how an automated process can determine the interpretation of shell nouns; second, the extent to which knowledge derived from the linguistics literature can help in this process; and third, the extent to which speakers of English are able to interpret shell nouns.I start with a pilot study to annotate and resolve occurrences of this issue in the Medline abstracts.The method follows a typical problem-solving procedure used in computational linguistics: manual annotation, feature extraction, and supervised machine learning.The results illustrate the feasibility of annotating and resolving shell nouns, at least in the closed domain of Medline abstracts.Next, I move to developing general algorithms to resolve a variety of shell nouns in the newswire domain.The primary challenge was that each shell noun has its own idiosyncrasies and there was no annotated data available for this task.I developed a number of computational methods for resolving shell nouns that do not rely on manually annotated data.