Saying Hello World with GROOVE- A Solution to the TTC 2011 Instructive Case

This report presents a solution to the Hello World case study [2] using GROOVE. We provide and explain the grammar that we used to solve the case study. Every requested question of the case study was solved by a single rule application. 1 GROOVE GROOVE1 [1] is a general purpose graph transformation tool set that uses simple labelled graphs. The core functionality of GROOVE is to recursively apply all rules from a predefined set (the graph production system – GPS) to a given start graph, and to all graphs generated by such applications. This results in a state space consisting of the generated graphs. The main component of the GROOVE tool set is the Simulator, a graphical tool that integrates (among others) the functionalities of rule and host graph editing, and of interactive or automatic state space exploration. 1.1 Host Graphs In GROOVE, the host graphs, i.e., the graphs to be transformed, are simple graphs with nodes and directed labelled edges. In simple graphs, edges do not have an identity, and therefore parallel edges (i.e., edges with same label, and source and target nodes) are not allowed. Also, for the same reason, edges may not have attributes. In the graphical representation, nodes are depicted as rectangles and edges as binary arrows between two nodes. Node labels can be either node types or flags. Node types [resp. flags] are displayed in bold [resp. italic] inside a node rectangle. 1.2 Rules The transformation rules in GROOVE are represented by a single graph and colours and shapes are used to distinguish different elements. Figure 1 shows a small example rule. • Readers. The black (continuous thin) nodes and edges must be present in the host graph for the rule to be applicable and are preserved by the rule application; • Embargoes. The red (dashed fat) nodes and edges must be absent in the host graph for the rule to be applicable