Research on context of implicit context-sensitive graph grammars.

Visual Programming Languages have been widely adopted in design and comprehension of sophisticated systems. Context-sensitive graph grammar formalisms are suitable tools for specifying these languages, since they are intuitive and possess sufficient expressive power and usability. Nevertheless, some of the formalisms whose contexts are implicitly or incompletely represented in productions, called implicit context-sensitive graph grammars, suffer inherent weakness in intuitiveness and limitations in parsing algorithms. To address these issues, this paper formally presents a notion of context on the underlying concepts of partial and total precedence relations, characterizes their fundamental properties, and establishes a connection between contexts and their instances (also called context graphs elsewhere), based on the Reserved Graph Grammar formalism, a representative of implicit graph grammars. Moreover, three typical applications of contexts are illustrated, which show that contexts can both facilitate the comprehension and design of implicit graph grammars so as to enhance their intuitiveness, and make the existent efficient parsing algorithms more widely applicable.