Immunology as a Metaphor for Computational ... - Napier University

Chapter 6. A Self-Organising SDM — SOSDM 156Average number of antigens inmore than one cluster403530252015105eighthquarterNumber of antigenshalf050 100 150 200 250 300 350 400 450 500Figure 6.7: Examining the number of antigens that bind to more than one antibodybind to more than one antibody, i.e. belong to more than one cluster — this is showngraphically in figure 6.7. This shows that as the number of antigens increases, the numberof antibodies binding to an antigen increases. These findings apply to all experiments.In small datasets, it is relatively straightforward for the antibodies to distinguishbetween each cluster. For very large datasets however, even though the antigens nominallybelong to separate clusters, there is likely to be a large overlap between items ineach cluster, especially as the length of the defined section characterising each clusterdecreases, and the number of antigens generated from that schema increases. Thus,the memory must generalise in order to accurately recall the large number of dataitems,despite the fact that items nominally belong to a finite set of clusters — this isachieved by allowing clusters to overlap. This effect is much more clearly apparent inthe quarter-schema and eighth-schema than it is for those using half-schema.6.5.3 Number of Iterations Required to Find the Best SolutionTable 6.1 shows the mean number of iterations required to produce the best solution forall experiments, with the corresponding standard deviations. We observe that the meanvalues show that the algorithm rapidly converges on a solution, however the algorithm