Sensitivity invariants for linear time-invariant networks

For a general linear time-invariant network it is shown that the sum of the sensitivities, of any order, of a network function over different parameter sets is invariant. An expression is derived for calculating the sum of
(k+l)
th-order sensitivities knowing the same for
k
th-order sensitivities. It is also shown that lower bounds for the quadratic sensitivity index may be obtained by using the firstorder sensitivity invariants.