Is there anisotropy in structural bias?

Genetic and Evolutionary Computation Conference Companion (GECCO Companion), pp. 1243–1250

Abstract

Structural Bias (SB) is an important type of algorithmic deficiency within iterative optimisation heuristics. However, methods for detecting structural bias have not yet fully matured, and recent studies have uncovered many interesting questions. One of these is the question of how structural bias can be related to anisotropy. Intuitively, an algorithm that is not isotropic would be considered structurally biased. However, there have been cases where algorithms appear to only show SB in some dimensions. As such, we investigate whether these algorithms actually exhibit anisotropy, and how this impacts the detection of SB. We find that anisotropy is very rare, and even in cases where it is present, there are clear tests for SB which do not rely on any assumptions of isotropy, so we can safely expand the suite of SB tests to encompass these kinds of deficiencies not found by the original tests.

Authors 5

1. Diederick Vermetten Aachen

   Leiden University

   Affiliation as printed

   Leiden University, The Netherlands

2. Anna V. Kononova Aachen

   Leiden University

   Affiliation as printed

   Leiden University, The Netherlands

3. Fabio Caraffini

   De Montfort University

   Affiliation as printed

   De Montfort University, Leicester, UK

4. Hao Wang Aachen

   Leiden University

   Affiliation as printed

   Leiden University, The Netherlands

5. Thomas Bäck Aachen

   Leiden University

   Affiliation as printed

   Leiden University, The Netherlands