formally expressing a compiler's operational semantics. Term graphs are also used as abstract machines capable of modelling chemical and biological computations as well as graphical calculi such as concurrency models. Term graphs can perform automated verification and logical programming since they are well-suited to representing quantified statements in first order logic. Symbolic programming software is another application for term graphs, which are capable of representing and performing computation with abstract algebraic structures such as groups, fields and rings. The TERMGRAPH conference focuses entirely on research into term graph rewriting and its applications. Classes of graph grammar and graph rewriting system Graph rewriting systems naturally group into classes according to the kind of representation of graphs that are used and how the rewrites are expressed. The term graph grammar, otherwise equivalent to graph rewriting system or graph replacement system, is most often used in classifications. Some common types are: Attributed graph grammars, typically formalised using either the single-pushout approach or the double-pushout approach to characterising replacements, mentioned in the above section on the algebraic approach to graph rewriting. Hypergraph grammars, including as more restrictive subclasses port graph grammars, linear graph grammars and interaction nets. Implementations and applications Graphs are an expressive, visual and mathematically precise formalism for modelling of objects (entities) linked by relations; objects are represented by nodes and relations between them by edges. Nodes and edges are commonly typed and attributed. Computations are described in this model by changes in the relations between the entities or by attribute changes of the graph elements. They are encoded in graph rewrite/graph transformation rules and executed by graph rewrite systems/graph transformation tools. Tools that are application domain neutral: AGG, the attributed graph grammar system (Java) GP 2 is a programming language for computing on graphs by the directed application of graph transformation rules. GMTE, the Graph Matching and Transformation Engine for graph matching and transformation. It is an implementation of an extension of Messmer’s algorithm using C++. GrGen.NET, the graph rewrite generator, a graph transformation tool emitting C#-code or .NET-assemblies GROOVE, a Java-based tool set for editing graphs and graph transformation rules, exploring the state spaces of graph grammars, and model checking those state spaces; can also be used as a graph transformation engine. Verigraph, a software specification and verification system based on graph rewriting (Haskell). Tools that solve software engineering tasks (mainly MDA) with graph rewriting: eMoflon, an EMF-compliant model-transformation tool