@article{OrejasPinoNavarroetal.2018,
  author    = {Orejas, Fernando and Pino, Elvira and Navarro, Marisa and Lambers, Leen},
  title     = {Institutions for navigational logics for graphical structures},
  series = {Theoretical computer science},
  volume    = {741},
  journal   = {Theoretical computer science},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0304-3975},
  doi       = {10.1016/j.tcs.2018.02.031},
  pages     = {19 -- 24},
  year      = {2018},
  abstract  = {We show that a Navigational Logic, i.e., a logic to express properties about graphs and about paths in graphs is a semi-exact institution. In this way, we can use a number of operations to structure and modularize our specifications. Moreover, using the properties of our institution, we also show how to structure single formulas, which in our formalism could be quite complex.},
  language  = {en}
}
@article{SchneiderLambersOrejas2018,
  author    = {Schneider, Sven and Lambers, Leen and Orejas, Fernando},
  title     = {Automated reasoning for attributed graph properties},
  series = {International Journal on Software Tools for Technology Transfer},
  volume    = {20},
  journal   = {International Journal on Software Tools for Technology Transfer},
  number    = {6},
  publisher = {Springer},
  address   = {Heidelberg},
  issn      = {1433-2779},
  doi       = {10.1007/s10009-018-0496-3},
  pages     = {705 -- 737},
  year      = {2018},
  abstract  = {Graphs are ubiquitous in computer science. Moreover, in various application fields, graphs are equipped with attributes to express additional information such as names of entities or weights of relationships. Due to the pervasiveness of attributed graphs, it is highly important to have the means to express properties on attributed graphs to strengthen modeling capabilities and to enable analysis. Firstly, we introduce a new logic of attributed graph properties, where the graph part and attribution part are neatly separated. The graph part is equivalent to first-order logic on graphs as introduced by Courcelle. It employs graph morphisms to allow the specification of complex graph patterns. The attribution part is added to this graph part by reverting to the symbolic approach to graph attribution, where attributes are represented symbolically by variables whose possible values are specified by a set of constraints making use of algebraic specifications. Secondly, we extend our refutationally complete tableau-based reasoning method as well as our symbolic model generation approach for graph properties to attributed graph properties. Due to the new logic mentioned above, neatly separating the graph and attribution parts, and the categorical constructions employed only on a more abstract level, we can leave the graph part of the algorithms seemingly unchanged. For the integration of the attribution part into the algorithms, we use an oracle, allowing for flexible adoption of different available SMT solvers in the actual implementation. Finally, our automated reasoning approach for attributed graph properties is implemented in the tool AutoGraph integrating in particular the SMT solver Z3 for the attribute part of the properties. We motivate and illustrate our work with a particular application scenario on graph database query validation.},
  language  = {en}
}
@article{LambersBornKosioletal.2018,
  author    = {Lambers, Leen and Born, Kristopher and Kosiol, Jens and Str{\"u}ber, Daniel and Taentzer, Gabriele},
  title     = {Granularity of conflicts and dependencies in graph transformation systems},
  series = {Journal of Logical and Algebraic Methods in Programming},
  volume    = {103},
  journal   = {Journal of Logical and Algebraic Methods in Programming},
  publisher = {Elsevier},
  address   = {New York},
  issn      = {2352-2208},
  doi       = {10.1016/j.jlamp.2018.11.004},
  pages     = {105 -- 129},
  year      = {2018},
  abstract  = {Conflict and dependency analysis (CDA) is a static analysis for the detection of conflicting and dependent rule applications in a graph transformation system. The state-of-the-art CDA technique, critical pair analysis, provides all potential conflicts and dependencies in minimal context as critical pairs, for each pair of rules. Yet, critical pairs can be hard to understand; users are mainly interested in core information about conflicts and dependencies occurring in various combinations. In this paper, we present an approach to conflicts and dependencies in graph transformation systems based on two dimensions of granularity. The first dimension refers to the overlap considered between the rules of a given rule pair; the second one refers to the represented amount of context information about transformations in which the conflicts occur. We introduce a variety of new conflict notions, in particular, conflict atoms, conflict reasons, and minimal conflict reasons, relate them to the existing conflict notions of critical pairs and initial conflicts, and position all of these notions within our granularity approach. Finally, we introduce dual concepts for dependency analysis. As we discuss in a running example, our approach paves the way for an improved CDA technique. (C) 2018 Elsevier Inc. All rights reserved.},
  language  = {en}
}