Introduction to Subject Area 'Charts'

The subject area ‘Charts’ groups together those projects that study visual specification formalisms or charts. Visual formalisms promise to support the use of formal methods in the engineering process of (embedded) software systems by being high-level languages that are equipped with a formal semantics in the elementary formalisms like temporal logic or finite state machines. The use of chart languages has a long tradition in the domain of systems engineering as a means to support the intuition of the designer and thereby to allow to cope with the complexity of systems under design. For example, the domain of programmable logic controllers (PLC’s) has a long history of graphical “programming languages”, from ladder diagrams to sequential function charts [1], in the domain of reactive systems Harel’s Statecharts [2] find widespread use, and also object-oriented analysis and design are accompanied by multiple visual formalisms, some of which finally merged into the Unified Modeling Language [3]. The aim of the DFG focus area program is the integration of software specification techniques for the application in the engineering sciences. As just pointed out, many specification techniques are visual formalisms hence the study of the exact formal semantics of existing charts languages and their integration are a prominent part of the focus area program.