Symbolic circuit analysis suffers from the exponential growth of expression complexity with circuit size. Therefore, either if the symbolic expressions are used for gaining insight into circuit operation or for repetitive computer-based evaluations, simplification becomes mandatory. This chapter reviews the different existing techniques for symbolic expression simplification, classifying them into three categories according to the step at which the simplification is performed: on the circuit equations, during the solution of the circuit equations or after the circuit equations have been solved. Pros and cons of each approach are discussed.
Keywords: Approximated symbolic analysis, approximation techniques, simplification before generation, graph reduction, matrix reduction, simplification after generation, simplification during generation, approximation error, symbolic term generation, two-graph method, matroid intersection, determinant decision diagram.