An augmentation of semantic networks is presented in which the various nodes and arcs are partitioned into "net spaces." These net spaces delimit the scopes of quantified variables, distinguish hypothetical and imaginary situations from reality, encode alternative worlds considered in planning, and focus attention at particular levels of detail.
R. Gaizauskas, H. Harkema, M. Hepple, und A. Setzer. Temporal Representation and Reasoning, 2006. TIME 2006. Thirteenth International Symposium on, Seite 188-195. (Juni 2006)