Constraints can be expressed as a network, where nodes
are linked if they are related by a binary constraint:

*Start(job _{2}) &ge Start(job_{1}) + 5*.

Higher-order constraints can be expressed by multiple binary constraints (by introducing additional variables) or represented as a hypergraph.

Example: [Russell & Norvig, Fig. 5.1.]

In this example, the nodes for states are linked if the states are
adjacent on the map; links represent *&ne* constraints.