@incollection{eprints144,
       publisher = {Springer},
            note = {{\copyright} Springer-Verlag Berlin Heidelberg 2010. The final publication is available at www.springerlink.com.},
          author = {Roberto Bruni and Fabio Gadducci and Alberto Lluch-Lafuente},
          editor = {Martin Wirsing and Martin Hofmann and Axel Rauschmayer},
       booktitle = {Trustworthly Global Computing (TCG 2010)},
          volume = {6084},
           pages = {205--221},
          series = {Lecture Notes in Computer Science},
           title = {An Algebra of Hierarchical Graphs},
            year = {2010},
             url = {http://eprints.imtlucca.it/144/},
        abstract = {We define an algebraic theory of hierarchical graphs, whose axioms characterise graph isomorphism: two terms are equated exactly when they represent the same graph. Our algebra can be understood as a high-level language for describing graphs with a node-sharing, embedding structure, and it is then well suited for defining graphical representations of software models where nesting and linking are key aspects.
}
}