Jump aboard the HMS Beagle

In this chapter we will give a lay-mans introduction to evolution and how it applies to the projects we are studying.

Evolution

Evolution tracks a population over time in their environment. A population consists of individuals. Individuals differ by there genetic makeup. The survival of the genetic makeup of an individual is determined by their fitness, i.e. how well they are adapted to their environment. Individuals that are fitter, have a higher chance of reproducing, allowing their genetic makeup to prosper.

Translation

Above we gave in broad strokes a general description of evolution. In this section we are going to paint a little bit more detail. We do this by providing a translation, from the general term to the specific term that we are going to use.

Individuals

Our individuals will be abstract syntax trees or AST for short. Abstract syntax trees are a means to accurately describe the structure of a certain program. We will use grammars to define which abstract syntax trees are allowed.

Genetic Makeup

The behavior of a program is determined by evaluating an AST. So the genetic makeup is the AST itself.

Environment

We have a number of environments that our AST will flourish in. The environments are described in the About chapter.

Fitness

The fitness of our AST will be measured by a fitness function. This is a function that tracks the performance of a AST in her environment and assigns a numerical value to it. This numerical value will be used to compare AST to determine their relative fitness.

Further reading

Below we have some suggestions on what to read next.

If you want to learn how to genetic programming works by and studying the nitty gritty details, work through all the chapters up to A Framework for Genetic Programming. It will teach you everything you need to know to work with, or create your own, genetic programming framework.

If you want to work on the AGC project, or work on your own problem, go to the A Framework for Genetic Programming chapter. It explains how to use the framework on the problem of landing a lunar lander on the surface of the moon. It is an ideal stomping ground to learn about the framework for your own use.

If you want to construct good fitness functions in order to let the lunar lander land safely on the surface of the moon, head over to Tweak Fitness Functions. There you can try to guide the safe landing of the lunar lander, by writing the fitness function.