Karr, Michael2015-11-091998Karr, Michael. Activity Graphs. Harvard Computer Science Group Technical Report TR-02-98.http://nrs.harvard.edu/urn-3:HUL.InstRepos:23518800This paper discusses activity graphs, the mathematical formalism underlying the Activity Coordination System, a process-centered system for collaborative work. The activity graph model was developed for the purpose of describing, tracking, and guiding distributed, communication-intensive activities. Its graph-based semantics encompasses the more familiar Petri nets, but has several novel properties. For example, it is possible to impose multiple hierarchies on the same graph, so that the hierarchy with which an activity is described does not have to be the one with which it is viewed. The paper also discusses very briefly some aspects of the system implementation.en-USsoftware process modelingprocess executiondistributed processescoordination modelsprocess formalismsResearch Paper or Report2015-11-09