Computer Laboratory

Technical reports

The acquisition of a unification-based generalised categorial grammar

Aline Villavicencio

April 2002, 223 pages

This technical report is based on a dissertation submitted September 2001 by the author for the degree of Doctor of Philosophy to the University of Cambridge, Hughes Hall.

The thesis was partially sponsored by a doctoral studentship from CAPES/Brazil.

Abstract

The purpose of this work is to investigate the process of grammatical acquisition from data. In order to do that, a computational learning system is used, composed of a Universal Grammar with associated parameters, and a learning algorithm, following the Principles and Parameters Theory. The Universal Grammar is implemented as a Unification-Based Generalised Categorial Grammar, embedded in a default inheritance network of lexical types. The learning algorithm receives input from a corpus of spontaneous child-directed transcribed speech annotated with logical forms and sets the parameters based on this input. This framework is used as a basis to investigate several aspects of language acquisition. In this thesis I concentrate on the acquisition of subcategorisation frames and word order information, from data. The data to which the learner is exposed can be noisy and ambiguous, and I investigate how these factors affect the learning process. The results obtained show a robust learner converging towards the target grammar given the input data available. They also show how the amount of noise present in the input data affects the speed of convergence of the learner towards the target grammar. Future work is suggested for investigating the developmental stages of language acquisition as predicted by the learning model, with a thorough comparison with the developmental stages of a child. This is primarily a cognitive computational model of language learning that can be used to investigate and gain a better understanding of human language acquisition, and can potentially be relevant to the development of more adaptive NLP technology.

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BibTeX record

@TechReport{UCAM-CL-TR-533,
  author =	 {Villavicencio, Aline},
  title = 	 {{The acquisition of a unification-based generalised
         	   categorial grammar}},
  year = 	 2002,
  month = 	 apr,
  url = 	 {http://www.cl.cam.ac.uk/techreports/UCAM-CL-TR-533.pdf},
  institution =  {University of Cambridge, Computer Laboratory},
  number = 	 {UCAM-CL-TR-533}
}