An execution model for demonstration-based visual languages

An abstract execution model for demonstration-based and example-based visual languages is presented. The formalism, causality graphs, are a simplified version of Petri nets, and possess similar execution properties. The author shows how programming, compilation, and execution of demonstration-based languages may be expressed as the construction and analysis of causality graphs. The model provides a basis for a theory of demonstration-based languages, and leads to a number of suggestions for the design and implementation of these languages