Diagram Schemas: What, Why, How

Abstract

Diagram schemas allow us to organize broad and deep collections of diagrams for theoretical analysis and system building. Formal intensional (rule-based) methods attempt to lay out the necessary and sufficient conditions for describing a class. For diagrams, it can be argued that the most useful schemas are extensional ones built around exemplars and prototypes based on central instances. Diagrams are then further classified in relation to these central instances. Many existing system designs use exemplar-based schemas implicitly. We describe how diagram exemplars and prototypes can be used in the design of a wide variety of systems for generating, parsing, machine learning, indexing and retrieval systems and contrast exemplars with rule-based approaches. Exemplar-based approaches are particularly well-suited for dealing with HCI issues.