The SMART operator population exists in two demes. A deme (the use of which is also called the ``island model'') is a section of a population whose members intra-breed with much higher frequency than they inter-breed with individuals from other demes [Collins 1992]. One deme is responsible for recombining the ADFs and the other for recombining the MAIN programs. Each generation included a single individual drift between these two demes. Each deme was of size 150 for a total SMART operator population of 300 individuals. Each SMART operator program was allowed access to one ADF and no library programs.
This chapter uses a simple application of the SMART operator
population to the main population (see
section 3.6.2 for alternatives). Each
operator gets R (equation 3.1) recombination attempts. Since the
was 2800 for the experiments in this chapter, and
the 
was 85% this means that each of the
SMART operators in the ADF deme take eight main population programs
(four sets of two), recombine their ADFs, and insert eight new
programs back into the main population. Each of the SMART operators
in the MAIN deme take eight main population programs, recombine their
MAIN programs, and insert eight new programs back into the main
population. Here is an overview of the co-evolution process with SMART
operators.
The fitness estimate in step 2 is based on current and previous main
population fitness values (see section 3.4.5 for
exactly how this is measured). Step 6 is accomplished by using RANDOM
recombination operators. See section 3.6.1
for alternatives. This process is co-evolution because the fitness of
programs in each population (main and SMART operator) has an effect on
the current (main 
SMART) or future (SMART 
main) fitnesses of the other population. The SMART operator population
can start with random or seeded individuals (see
section 3.6.3).
