Sensitivity invariants for nonlinear networks

For a general class of nonlinear networks, explicit expressions for sensitivities of a response due to nonlinear elements are derived. These expressions are used to establish invariance relationships for the sums of sensitivities over different sets of parameters of two classes of nonlinear networks. It is indicated how these relationships can be used to establish the invariant nature of the sum of higher order sensitivities and a lower bound for the quadratic sensitivity index.