Evolutionary Algorithms with String Representations Summary: Chapter 2 Evolutionary Algorithms with String Representations The simplest evolutionary algorithms store the members of their evolving populations as fixed length strings over a simple alphabet. This type of evolutionary algorithm is called a string evolver. A simple evolutionary algorithm may solve a simple problem or a difficult one. The difficulty of the problem a string evolver is solving depends primarily on the fitness function and, to a lesser degree, on the way the variation operators are designed. Another important factor is the population size. 2.1 The Simple Evolutionary Algorithm We begin by defining a number of terms. An alphabet is a set of characters. A string is a finite sequence of characters over (with characters from) some alphabet. Example 2.1 The binary alphabet is {0, 1}. Examples of strings over the binary alphabet are 0, 01, and 10101001. Definition 2.1 If A is an alphabet then An is the set of all strings of length n over A. The set of all strings over A is denoted A . Example 2.2 {a, b, c}2 = {aa, ab, ac, ba, bb, bc, ca, cb, cc} Collections: Mathematics