Visual notation and patterns for abstract state machines

Formal models are a rigorous way to specify informal system requirements. However, they are not widely used in practice, since they are considered difficult to develop and understand. Visualization is often considered a good means for people to communicate and to get a common understanding. We here make a proposal of a visual notation for Abstract State Machines (ASMs), and we introduce visual trees that visualize ASM transition rules. In addition to these graphical components that are based only on the syntactical structure of the model, we also present visual patterns that permit to visualize part of the behavior of the machine. A tool is also available to graphically represent ASM models using the proposed notation.