SLRT applies whenever the driving is strong enough such that relaxation to the steady state is slow compared with the driven dynamics. Yet one assumes that the system can be modeled as a resistor network, mathematically expressed as G = [ [ G n m ] ] . The notation [ [ G n m ] ] stands for the usual electrical engineering calculation of a two terminal conductance of a given resistor network. For example, parallel connections imply G = ∑ ∑ n m G n m , while serial connections imply G = [ ∑ ∑ n m G n m − − 1 ] − − 1 . Resistor network calculation is manifestly semi-linear because it satisfies [ [ λ λ A ] ] = λ λ [ [ A ] ] , but in general [ [ A + B ] ] ≠ ≠ [ [ A ] ] + [ [ B ] ] .