Modeling and Using Context: 25 Years of Lessons Learned

Abstract

Modeling and Using Context: 25 Years ofLessons Learned 1This chapter presents the results of 25 years of research on modeling and using context in realworld applications. The first milestone was an operational definition of context relating it to a focus (problem-solving, decision-making, task realization). The focus provides context with links between context and knowledge, a division between contextual knowledge and external knowledge with respect to a focus, and a dynamic linked to reasoning evolution. Conversely, context makes focus more explicit. The second milestone was a context-based representation of decision trees as contextual graphs with contextual elements (expressing the focus) instead of chance or event nodes. The operational definition of context opens up a conceptual framework that can be associated with an implementation framework. The third milestone was the development of a context-based representation formalism that led to the software Contextual Graphs (CxG) that has been used in about 20 real-world applications. The fourth milestone concerns an extension of the CxG representation formalism for representing group activity with a cyclic use of a CxG for simulation purposes. The formalism now allows a modeling of "nonlinear" behaviors of a group (e.g. interaction, negotiation, etc.) as well as of a user (e.g. checking alternatives). The fifth milestone opens the way to Context-based Intelligent Assistant Systems.