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Gene Libraries: Coverage, Efficiency and Diversity
Steve Cayzer 1 and Jim Smith 2
1 HP Laboratories, Bristol BS34 8QZ UK
steve.cayzer@hp.com
2 University of the West of England, Bristol BS16 1QY UK
james.smith@uwe.ac.uk
Abstract. Gene libraries are a biological mechanism for generating combinatorial
diversity in the immune system. However, they also bias the antibody creation
process, so that they can be viewed as a way of guiding lifetime learning
mechanisms. In this paper we examine the implications of this view, by
examining coverage, avoidance of self, clustering and diversity. We show how
gene libraries may improve both computational expense and performance, and
present an analysis which suggests how they might do it. We suggest that gene
libraries: provide combinatorial efficiency; improve coverage; reduce the cost of
negative selection; and allow targeting of fixed antigen populations.
Keywords: gene libraries, artificial immune systems, antibodies, diversity,
Baldwin effect, lifetime learning.
1 Introduction
Immune systems in nature must recognise undesirable antigens while avoiding auto
immune reactions. Gene libraries may help both aims; by providing initialisation bias
away from self space; and by providing a species memory to map antigen space. What
could this mean for AIS? Could gene libraries be used to intelligently seed our
algorithm? In a previous paper [1] we postulated that gene libraries might:
1. improve non-self space coverage - through better placement of detectors
(antibodies), over and above random creation;
2. reduce the cost of detector generation by more effectively avoiding self;
3. map the antigen population more accurately; and
4. help deal with co-evolving antigens
In that paper, we showed that option 2 is somewhat easier to achieve than option 1.
Here we extend and analyse these results, and tackle option 3. Option 4 is left for
future work. The rest of this paper proceeds as follows.
In Section 2 we review the biological background and related AIS research. In
Section 3 we provide an initial analysis of the effect of evolving different numbers of
libraries in the presence of uniformly distributed populations of self and non-self
(antigen) strings. We show that gene libraries can attain superior coverage in this
case, and that 2 libraries work as well as, even better than, 1 library. This is
significant given the combinatorial advantages of using multiple libraries. All libraries
 
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