What are canalysing functions and forcing structures ?
A function is canalysing if a single input being in a fixed state is sufficient to force the output to a fixed state, regardless of the state of any other input. For example, for an AND gate if any input is held low then the output is forced, low, so this function is canalysing. An XOR gate, in contrast, is not since the state can always change by varying another input. The result of connecting a series of canalysing functions can be to force chunks of the network to a fixed state (an initial fixed input can ripple through and lock up part of the network – a forcing structure). Such fixed divisions (barriers to change) can break up the network into active and passive structures and this allows complex behaviours to develop.
