Deening Visual Languages by Algebraic Speciication Techniques and Graph Grammars

This contribution follows the line of research to formally deene a visual language by algebraic concepts and techniques. In this paper, a graphic i.e. a sentence of a visual language, is equipped with an underlying graph structure. This is done in a way that each graph object of the graph structure is represented by a graphic which may be a complex one. Graph structures are regarded as n-sorted algebras to equational speciications. The symbols of the underlying alphabet are visually represented by graphics and formulated by diierent sorts. The operations deene how the symbols are linked and the equation part formulates layout constraints. Algebraic graph grammars are used to describe the visual language by using the predeened symbols and links. Based on these theoretical concepts we sketch how a visual language can be visually deened using diierent graphical editors.