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## SMART Operator Co-evolution Mechanics

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.

1. Measure approximate fitness of each main population program.
2. Measure approximate fitness of each SMART operator program.
3. Perform Fitness Proportionate Reproduction on main population.
4. Perform Sexual Recombination on main population using SMART operators.
5. Perform Fitness Proportionate Reproduction on SMART operator population.
6. Perform Sexual Recombination on SMART operator population.

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).

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Eric Teller
Tue Oct 29 17:04:55 EST 1996