Editing Hashlife (section)

===Hashing===
A [[hash table]], or more generally any kind of [[associative array]], may be used to map square contents to an already existing node representing those contents, so that one through the technique of [[hash consing]] may avoid creating a duplicate node representing those contents. If this is applied consistently then it is sufficient to hash the four pointers to component nodes, as a bottom–up hashing of the square contents would always find those four nodes at the level below. It turns out several operations on higher level nodes can be carried out without explicitly producing the contents of those nodes, instead it suffices to work with pointers to nodes a fixed number of levels down.