3 Koza, John R. III, Forrest H Bennett Andre, David Keane, Martin A 1996 Tetsuya Higuchi and Iwata Masaya and Weixin Liu Lecture Notes in Computer Science Tsukuba, Japan Springer-Verlag 1259 "7-8 " # oct 3-540-63173-9 genetic algorithms, genetic programming Most practical electrical circuits contain modular substructures that are repeatedly used to create the overall circuit. Genetic programming with automatically defined functions and architecture-altering operations successfully evolved a design for a two-band crossover (woofer and tweeter) filter with a crossover frequency of 2,512 Hz. Both the topology and the sizing (numerical values) for each component of a the circuit were evolved. In the evolved circuit, three different electrical substructures were used; one was invoked five times; and one was invoked as part of a hierarchy; and one substructure was invoked with different Numerical arguments so that different numerical component values were assigned to the substructure's components. http://www.genetic-programming.com/jkpdf/ices1996jkreuse.pdf