Our efforts to extend and enhance conceptual graphs took three different directions:
The ontology was developed in a paper "A uniform representation for time and space and their mutual constraints" for the Journal of Computers and Mathematics with Applications 23:6-9, pp. 441-457, 1992. This paper also describes the extensions for representing causal rules in conceptual graphs. The major application of the procedural extensions came in the model generative reasoning system, developed using conceptual graphs as a representational base.