Visualisation of Building Blocks in Evolutionary Algorithms

Building blocks are solutions to sub-parts of a problem which can help in the formation of good solutions to the whole problem. Building blocks are widely recognised as important elements in the successful application of evolutionary algorithms (EAs), but there is as yet no general method by which the building blocks of a problem can be identified. We describe and evaluate a new system which creates a visual representation of these building blocks by displaying the possible gene values of a problem on a canvas, with the distance between the nodes representing two values determined by the number of individuals in the population which contain both values. Building blocks then appear as clusters of nodes, and they can be identified easily: moreover, the evolution of the building blocks as the EA proceeds can be tracked. This system will help in understanding the structure of problems and in tuning EAs to solve them well.