Use of automatically defined functions and architecture-altering operations in automated circuit synthesis with genetic programming
This paper demonstrates the usefulness of automatically defined functions and architecture-altering operations in designing analog electrical circuits using genetic programming. 
 
A design for a lowpass filter is genetically evolved in which an automatically defined function is profitably reused in the 100% compliant circuit. The symmetric reuse of an evolved substructure directly enhances the performance of the circuit. Genetic programming rediscovered the classical ladder topology used in Butterworth and Chebychev filters as well as the more complex topology used in Cauer (elliptic) filters. 
 
A design for a double-passband filter is genetically evolved in which the architecture-altering operations discover a suitable program architecture dynamically during the run. Two automatically defined functions are profitably reused in the genetically evolved 100% complaint circuit.