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

Chapter 6. A Self-Organising SDM — SOSDM 16643.5Mean recalled accuracy4342.54241.51000 2000 3000 4000 5000 6000 7000 8000 9000 10000Size of antigen datasetFigure 6.12: The figure shows how mean recalled accuracy r varies with the size of theantigen dataset Nthe algorithm. Experiments were repeated 50 times in each case. Figure 6.12 showsthe performance of SOSDM vs the size of the dataset, with error-bars showing theminimum and maximum accuracy over the 50 experiments. Note that although thereis a slight downwards trend in mean recalled accuracy r, the value of r is always significantlygreater than the result that would be obtained using the best possible stringgeneralist, which would give r 40. T-tests show what there is a significant difference(p 0¦ 99) in the value of r obtained for N 1000 and that obtained when N 10¤ 000.¡6.6.4 Performance vs Length of AntigenA second series of experiments used datasets generated again from quarter-schema,this time of fixed size N=200 antigens. The length of the antigen L in each dataset wasvaried from 40 to 1000 in steps of 40. The best recalled accuracy r was measured atthe end of 200 iterations of SOSDM, and the results averaged over 50 trials. Figure6.13 shows the results of these experiments; a comparison is made to the mean recallaccuracy that would be expected using the best possible single string generalist for eachvalue of L. The figure shows a direct correspondence between r and L — again, forevery value of L , the value of r exceeds that expected using the single string generalist