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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 a behavioral description of the surrounding environment. The Unified Modeling Language as used in systems engineering defines a context model as the physical scope of the system being designed, which could include the user as well as the environment and other actors. A System context diagram represents the context graphically.. Several examples of context models occur under other domains. * 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. )〕 * 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. )〕 * Within an ontology, a context model provides disambiguation of a subject via semantic analysis of information related to the subject. * 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 )〕 == References == 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Context model」の詳細全文を読む スポンサード リンク
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