Now showing 1 - 5 of 5
  • Publication
    Investigating mapping order in πGE
    We present an investigation into the genotype-phenotype map in Position Independent Grammatical Evolution (πGE). Previous studies have shown πGE to exhibit a performance increase over standard GE. The only difference between the two approaches is in how the genotype-phenotype mapping process is performed. GE uses a leftmost non terminal expansion, while πGE evolves the order of mapping as well as the content. In this study, we use the idea of focused search to examine which aspect of the πGE mapping process provides the lift in performance over standard GE by applying our approaches to four benchmark problems taken from specialised literature. We examined the traditional πGE approach and compared it to two setups which examined the extremes of mapping order search and content search, and against setups with varying ratios of content and order search. In all of these tests a purely content focused πGE was shown to exhibit a performance gain over the other setups.
    Scopus© Citations 3  503
  • Publication
    Investigation of the performance of different mapping orders for GE on the max problem
    We present an analysis of how the genotype-phenotype map in Grammatical Evolution (GE) can effect performance on the Max Problem. Earlier studies have demonstrated a performance decrease for Position independent Grammatical Evolution (πGE ) in this problem domain. In πGE the genotype-phenotype map is changed so that the evolutionary algorithm controls not only what the next expansion will be but also the choice of what position in the derivation tree is expanded next. In this study we extend previous work and investigate whether the ability to change the order of expansion is responsible for the performance decrease or if the problem is simply that a certain order of expansion in the genotype-phenotype map is responsible. We conclude that the reduction of performance in the Max problem domain by πGE is rooted in the way the genotype-phenotype map and the genetic operators used with this mapping interact.
      417Scopus© Citations 4
  • Publication
    Modelling fairness in Food Value Chains: Developing quantitative indicators
    To provide tools and approaches to enable decision makers in food value chains to evaluate the impact of strategic and operational policies aimed at enhancing fairness, integrity, resilience in future scenarios of sustainable food value chains (FVCs). Fairness in food value chains (FVCs) is topical and policy-relevant. Thus there is value in exploring its dynamics through simulation modeling.
      84
  • Publication
    An analysis of genotype-phenotype maps in grammatical evolution
    We present an analysis of the genotype-phenotype map in Grammatical Evolution (GE). The standard map adopted in GE is a depth-first expansion of the non-terminal symbols during the derivation sequence. Earlier studies have indicated that allowing the path of the expansion to be under the guidance of evolution as opposed to a de- terministic process produced significant performance gains on all of the benchmark problems analysed. In this study we extend this analysis to in- clude a breadth-first and random map, investigate additional benchmark problems, and take into consideration the implications of recent results on alternative grammar representations with this new evidence. We con- clude that it is possible to improve the performance of grammar-based Genetic Programming by the manner in which a genotype-phenotype map is performed.
      624Scopus© Citations 29
  • Publication
    Ethnography in and around an Algorithm
    If 'headwork' is "the conceptual work that informs ethnographic fieldwork and its various representational practices", then this paper is a piece of headwork about what an ethnography in (or around, or of) an algorithm might entail. We begin by situating this question in ethnography’s long tradition of philosophical reflection on method and representation. This reflection has been deep and cutting, and some would argue that it has evacuated ethnography of its essence, identify and value.
      954