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On the Avoidance of Fruitless Wraps in Grammatical Evolution

  • Conor Ryan
  • Maarten Keijzer
  • Miguel Nicolau
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 2724)

Abstract

Grammatical Evolution (GE) is an evolutionary system that employs variable length linear chromosomes to represent computer programs. GE uses the individuals to produce derivation trees that adhere to a Backus Naur Form grammar, which are then mapped onto a program. One unusual characteristic of the system is the manner in which chromosomes can be “wrapped”, that is, if an individual has used up all of its genes before a program is completely mapped, the chromosome is reread. While this doesn’t guarantee that an individual will map, prior work suggested that wrapping is beneficial for the system, both in terms of increased success rates and a reduced number of invalid individuals. However, there has been no research into the number of times an individual should be wrapped before the system gives up, and an arbitrary upper limit is usually chosen.

This paper discusses the different types of grammars that could be used with this system, and indicates the circumstances under which individuals will fail. It then presents a heuristic to minimize the number of wraps that have to be made before the system can determine that an individual will fail. It is shown that this can drastically reduce the amount of wrapping on a pathologically difficult problem, as well as on two classes of grammar often used by the system.

Keywords

Context Free Grammar Symbolic Regression Grammatical Evolution Increase Success Rate Shape Graph 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2003

Authors and Affiliations

  • Conor Ryan
    • 1
  • Maarten Keijzer
    • 2
  • Miguel Nicolau
    • 1
  1. 1.Department Of Computer Science And Information SystemsUniversity of LimerickIreland
  2. 2.CS Dept.Free UniversityAmsterdam

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