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CHAPTER 2

A Model of Landscapes

This chapter presents the landscape model that will be used as a framework for the remainder of the dissertation. It is assumed that one's aim is to address a search problem. It is possible to adopt more neutral language, to the point that the model seems completely abstract. However, adopting the language of search does not restrict applicability too severely. One argument for neutrality is that since the model is applicable to situations that some people would not consider search, it should be described in a general way that will permit its easy application to these fields. A counter argument holds that most of what we do, especially with computers, can be phrased in terms of search. If the landscape model presented here is useful in some field of endeavor, then it is probably possible to describe that endeavor as a search. As will be seen, choosing to view a wide range of situations from a search perspective is not without precedent.

2.1. Motivation

Given the aim of this chapter, to present a model of landscapes, there are many preliminary questions that should be addressed before the model is presented. Three of these are particularly important.

ffl What is a landscape?
A landscape is one way to view some aspects of a complex process. As such, it is a tool that we hope to use to increase understanding of the process, to suggest explanations and ideas, and to provide an intuitive feeling for those aspects of the process. This description is vague because landscapes may be used in a wide variety of situations. Wright employed the metaphor to provide a simplified and intuitive picture of his work on the mathematics of gene flow in a population [37]. We will use landscapes to produce a simplified view of some