uz_computersimul.pdf

Seminar fur Computerlinguistik

Institut fur allgemeine und angewandte Sprachwissenschaft

Ruprecht-Karls-Universitat Heidelberg

Magisterarbeit

Computer Simulation of Language Evolution

Ste®en Eger

26 January 2007

Supervisors:

Dr. Markus Demleitner

and

Prof. Dr. Peter Hellwig

Abstract

This master thesis presents a computational approach to the problem of language evolution,

the study of how language emerges from a situation in which there is no language. The model

employed is inspired by the work done in Livingstone (2002) and Livingstone and Fyfe (1999).

The structure of the thesis is as follows: Chapter 2 introduces the basic terminology and results

of dialectology and language change. Chapter 3 gives an overview of the simulation model

and the details of implementation. Chapter 4 provides an analysis of the model’s parameters

and discusses the results observable for the ‘basic’ implementation. Chapter 5 describes the

setup and outcomes of genuinely novel experiments; these include the study of the emergence

of simple compositional grammars. Chapter 6 recapitulates the ﬁndings obtained and relates

these to questions of general linguistic importance.

Preface

Ah, distinctly I remember it was in the bleak December,

And each separate dying ember wrought its ghost upon the ﬂoor.

(Edgar Allan Poe, The Raven).

Orthographic conventions

The text presented in this master thesis is supposed to be written following the conven-

tions of American English. This means that the spelling, say, favor was favored over other

possible spellings, such as favour. However, since the distinction between the varieties of

English is, in the view of the author of this thesis, a matter of tendencies and probabili-

ties rather than an issue of binary oppositions, certain liberties were exercised - possibly

depending on the mood and disposal of the author - as to the spelling of such words

as, say, analyse versus analyze. Concerning the use of pronouns, the feminine version -

contrary to the business of most other present day literature, which endeavor to establish

‘some sort of equality’ - was employed when the confusion of the (current) reader was

thereby not unnecessarily provoked. Exceptions in this sense were cases like the learner

updates the weights of his net where the learner most likely - and actually - refers to an

artiﬁcial agent but the term is general enough to not exclude the possibility of the learner

being human. I felt that such instances would cause the alienation of the current reader

unless the traditional, longer established masculine pronoun were chosen. References to

an agent or agents were made - the idea of an ‘agent’ being that of a non-human, artiﬁcial

machine in this work’s context - in the neutral form because it was not believed that the

employment of, for example, she was justiﬁed in these cases; even less so that of he and

associates. Punctuation, in particular comma placement, was exerted with the proverb

iii

PREFACE

“if some is good, more is better” in mind. Furthermore, it is a pity that the common

English writer seems to do so well without the colon; I dearly missed it. Finally, the

excessive usage of parentheses is a thorn in the eye and an obstacle to ﬂuent reading

(but, unfortunately, the author of this work seems to have the persistent belief that he

has still something more to say).

Heidelberg, January 11, 2007

Contents

Preface

iii

1 Introduction

1.1 Language evolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.2 Computer Simulation of Language Evolution . . . . . . . . . . . . . . . .

1.3 The model at issue here . . . . . . . . . . . . . . . . . . . . . . . . . . .

2 Linguistic background

2.1 Dialect and language . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.2 Isoglosses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.3 Sociolinguistic approaches to dialectology . . . . . . . . . . . . . . . . . .

2.4 Language change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

3 Implementational Details

3.1 A simple model for the evolution of language . . . . . . . . . . . . . . . . 16

3.2 What does the updating rule do? . . . . . . . . . . . . . . . . . . . . . . 18

3.3 Spatial organization of agents . . . . . . . . . . . . . . . . . . . . . . . . 19

4 Analysis

4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

4.2 An introductory example . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

4.3 The role of inter-child training . . . . . . . . . . . . . . . . . . . . . 32

4.4 The role of ¾ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

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