Genetic algorithms three-descriptor models

We present results for two- and three-descriptor models addition of a fourth descriptor yielded no significant improvement in predictive accuracy. In the two-descriptor case there are only 276 possible input combinations, so we examine each explicitly, whereas, in the three-descriptor case there are 2024, so we use the genetic algorithm (GA) to optimize the descriptor selection. Use of the GA in the two-descriptor case gives models of comparable quality to the exhaustive search, but this test of the algorithm is not very stringent because the space of input combinations is small. Because both the GA and the NN depend on the random number generator seed, several trials were performed in each case (as detailed in Section IV.D.2). 

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