The objective function for the XOR experiment

In the XOR experiment, the fitness of the organism in the population is defined as the squared distance between the correct answer and the sum of the outputs that are generated for all four XOR input patterns. It is computed as follows:

1. The phenotype ANN is activated against all four XOR input patterns.
2. The output values are subtracted from the correct answers for each pattern, and the absolute values of the results are then summed.
3. The error value that was found at the previous step is subtracted from the maximal fitness value (4) to calculate organism fitness. The highest fitness value means better solver performance.
4. The calculated fitness is then squared to give proportionally more fitness to the organisms, thereby producing solver ANNs that give closer answers to the correct solution. This approach makes the evolutionary pressure...