*"triggers", which arrive from other queues or from outside the network, and which displace customers and move them to other queues
A [[product-form solution]] superficially similar in form to [[Jackson's theorem (queueing theory)|Jackson's theorem]], but which requires the solution of a system of non-linear equations for the traffic flows, exists for the stationary distribution of G-networks while the traffic equations of a G-network are in fact surprisingly non-linear, and the model does not obey partial balance. This broke previous assumptions that partial balance was a necessary condition for a product-form solution. A powerful property of G-networks is that they are universal approximators for continuous and bounded functions, so that they can be used to approximate quite general input-output behaviours.<ref>{{ cite journal | title = Function approximation with spiked random networks | first1 = Erol | last1 = Gelenbe | first2 = Zhi-Hong | last2 = Mao | first3 = Yan | last3 = Da Li | journal = IEEE Transactions on Neural Networks| volume = 10 | number = 1 | pages = 3–9 | year = 1999 | doi=10.1109/72.737488| pmid = 18252498 | citeseerx = 10.1.1.46.7710 }}</ref>
