Computer science [and network systems]
The networks discussed here can be thought of as very simple analogs of data structures in practical computer programs. The connections correspond to pointers between elements of these data structures. The fact that there are two connections coming from each node is reminiscent of the Lisp language, but in the networks considered here there are no leaves corresponding to atoms in Lisp. Note that the process of dropping nodes that become disconnected is analogous to so-called "garbage collection" for data structures. The networks considered here are also related to the combinator systems discussed on page 1121.