Higraph (original) (raw)

A higraph is a diagramming object that formalizes relations into a visual structure. It was developed by David Harel in 1988. Higraphs extend mathematical graphs by including notions of depth and orthogonality. In particular, nodes in a higraph can contain other nodes inside them, creating a hierarchy. The idea was initially developed for applications to databases, knowledge representation, and the behavioral specification of complex concurrent systems using the higraph-based language of statecharts.