A context model is used to define the enclosing environment of some system under study. In other words, the context is the surrounding element for the system, and a model provides the mathematical interface and behavior of the surroundings.

Several examples of context models

1. In the situation of parsing a grammar, a context model defines the surrounding text of a lexical element. This enables a context sensitive grammar that can have deterministic or stochastic rules. In the latter case, a hidden Markov model can provide the probabilities for the surrounding context.  Klein, Dan, and Christopher D. Manning. “A generative constituent-context model for improved grammar induction.” In Proceedings of the 40th Annual Meeting on Association for Computational Linguistics, pp. 128-135. Association for Computational Linguistics, 2002.
2. A context model can also apply to the surrounding elements in a gene sequence. Like the context rules of a grammar disambiguating a lexical element, this helps to disambiguate the role of the gene. Delcher, Arthur L., Douglas Harmon, Simon Kasif, Owen White, and Steven L. Salzberg. “Improved microbial gene identification with GLIMMER.” Nucleic acids research 27, no. 23 (1999): 4636-4641
3. Within an ontology, a context model provides disambiguation of a subject via semantic analysis of information related to the subject. Wang, Xiao Hang, D. Qing Zhang, Tao Gu, and Hung Keng Pung. “Ontology based context modeling and reasoning using OWL.” In Pervasive Computing and Communications Workshops, 2004. Proceedings of the Second IEEE Annual Conference on, pp. 18-22. IEEE, 2004.
   Gu, Tao, Xiao Hang Wang, Hung Keng Pung, and Da Qing Zhang. “An ontology-based context model in intelligent environments.” In Proceedings of communication networks and distributed systems modeling and simulation conference, vol. 2004, pp. 270-275. 2004.
4. In terms of a physical environment, a context model defines the external interfaces that a system will interact with. This type of context model has been used to create models for virtual environments such as the Adaptive Vehicle Make program. A context model used during design defines land, aquatic, or atmospheric characteristics (stated in terms of mathematical algorithms or a simulation) that the eventual product will face in the real environment. Component, Context, and Manufacturing Model Library – 2 (C2M2L-2), Broad Agency Announcement, DARPA-BAA-12-30, February 24, 2012

The Context/Earth project concentrates on the last application, which is to model elements of the environment which have some significance to systems analysis. Yet, because it uses a semantic web infrastructure, we also pay heed to providing the correct context in ontological terms and in expressing the grammar of use in concise and correct a fashion as possible.

Stay tuned for a sequence of posts that will elaborate on the world of context.