Abstract
This thesis presents a novel use of Genetic
Programming (GP) to evolve recurrent, weightless neural
networks. The approach taken uses neural network
construction rules as the data structures that undergo
adaptation by the GP algorithm. These rules can be used
to construct a neural network by adding neurons and
connections to an initial basic network configuration.
In addition to evolving the architectures of networks,
the system evolves the formulae for the activation
function of each neuron in the networks and the number
of processing cycles for the networks.
The system has been applied to a number of Boolean
functions and it is shown that solution networks were
able to be found for each. Some variations in the
system design were investigated on the Boolean
functions to identify possible improvements that could
be made to the system which would result in better
performance. One variation to the system design which
resulted in a significantly large increase in the
system performance was made by changing the
construction rules that are used by the system.
A number of characteristics of the produced networks
were noted. Among them is the generation of network
construction rules that are similar to each other. A
system variation was made which succeeded in making the
rules more diverse but does not generally result in
better performance. Another characteristics of the
networks is that their construction rules often contain
unused and redundant rules.
The construction rules were designed to allow efficient
specification of networks which contain multiple
instances of the same sub-network. The system uses this
when discovering solution networks for Boolean
functions which can be decomposed into two identical
Boolean functions. Importantly, the system achieved
significantly better results than a modified version of
the system in which the features enabling efficient
network specification were not present. This suggests
that incorporating a modular construction process for
building networks is useful for obtaining solution
networks to decomposable problems.
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