Activity Modeling and IDEF0

Occurrences, such as activities, events and processes can be modeled as higher order relations. This includes modeling of business processes and activities as well as modeling of physical and chemical processes. Gellish activity and process models are typically integrated with models of products, fluids, facilities and with organizational models.
 
A higher order relation can be expressed as a collection of binary relations, each of which specifies the role that a particular involved object plays in the occurrence. Thus the occurrence itself is an 'object' towards the other objects play their role in the various binary relations.
For example, a project is an occurrence in which several parties play a role, such as:
 
Project X <has as manager> John
Project X <has as subject> The Eiffel Tower
Project A <has as start date> 1 Jan 2014
etc.

IDEF0 is a well known and widely used graphical method for activity modeling.

The combined Gellish-IDEF0 Modeling Method is a method that stores the activity models in Gellish Databases. This includes also the logic to generate IDEF0 diagrams. Optionally the models may be integrated with models of products, facilities or organizations. The Gellish Modeling Method provides guidance on how to develop or use Gellish-IDEF0 powered software that can generate IDEF0 diagrams from such a database, and vice-versa (!) or that can support that modifications that are made in the diagrams are reflected in the database.