@inbook{7515,
  abstract     = {{The algebraic approaches to graph transformation are based on the concept of gluing of graphs corresponding to pushouts in suitable categories of graphs and graph morphisms. This allows one to give not only an explicit algebraic or set theoretical description of the constructions but also to use concepts and results from category theory in order to build up a rich theory and to give elegant proofs even in complex situations. In the previous chapter we have presented an overview of the basic notions and problems common to the two algebraic approaches the double pushout DPO approach and the single pushout SPO approach and their solutions in the DPO approach. In this chapter we introduce the SPO approach to graph transformation and some of its main results. We study application conditions for graph productions and the transformation of more general structures than graphs in the SPO approach where similar generalizations have been or could be studied also in the DPO approach. Finally we present a detailed comparison of the DPO and the SPO approach especially concerning the solutions to the problems discussed for both approaches in the previous chapter.}},
  author       = {{Ehrig, Hartmut and Heckel, Reiko and Korff, Martin and Löwe, Michael and Ribeiro, Leila and Wagner, Annika and Corradini, Andrea}},
  booktitle    = {{Handbook of Graph Grammars and Computing by Graph Transformations, Volume 1: Foundations}},
  pages        = {{247--312}},
  publisher    = {{World Scientific}},
  title        = {{{Algebraic Approaches to Graph Transformation, Part II: Single Pushout Approach and Comparison with Double Pushout Approach}}},
  year         = {{1997}},
}

@inbook{7516,
  author       = {{Engels, Gregor and Rekers, Jan and Andries, Marc}},
  booktitle    = {{Visual Language Theory}},
  pages        = {{241--255}},
  publisher    = {{Springer}},
  title        = {{{How to represent a visual specification}}},
  year         = {{1997}},
}

@inbook{7517,
  abstract     = {{The algebraic approaches to graph transformation are based on the concept of gluing of graphs, modelled by pushouts in suitable categories of graphs and graph morphisms. This allows one not only to give an explicit algebraic or set theoretical description of the constructions, but also to use concepts and results from category theory in order to build up a rich theory and to give elegant proofs even in complex situations. In this chapter we start with an overwiev of the basic notions common to the two algebraic approaches, the double-pushout (DPO) approach and the singlepushout (SPO) approach; next we present the classical theory and some recent development of the double-pushout approach. The next chapter is devoted instead to the single-pushout approach, and it is closed by a comparison between the two approaches.}},
  author       = {{Corradini, Andrea and Montanari, Ugo and Rossi, Francesca and Ehrig, Hartmut and Heckel, Reiko and Löwe, Michael}},
  booktitle    = {{Handbook of Graph Grammars and Computing by Graph Transformation, Volume 1: Foundations}},
  pages        = {{163--245}},
  publisher    = {{World Scientific}},
  title        = {{{Algebraic Approaches to Graph Transformation, Part I: Basic Concepts and Double Pushout Approach}}},
  year         = {{1997}},
}

@proceedings{7796,
  editor       = {{Engels, Gregor and Ehrig, Hartmut and Rozenberg, Grzegorz and Skowron, Andrzej}},
  number       = {{3-4}},
  publisher    = {{IOS Press}},
  title        = {{{Special Issue on Graph Transformations}}},
  volume       = {{26}},
  year         = {{1996}},
}

@inproceedings{7834,
  abstract     = {{The concept of views is used on two levels. First, so-called design views are developed for structuring specifications, that is, a system is modeled according to different views (e.g., representing the needs of different kinds of users) which have to be synchronized afterwards in order to build the whole system. Views can be specified by means of typed graph transformation systems, where the type graph determines the visible types and the productions describe the known operations of that view. The synchronization of views is done by the construction of cooperative parallel composition of graph transformation systems, developed by Leila Ribeiro and presented at the same seminar. If the specification is complete, a view may describe an observation of the system in operation. In this case we speak of a user view. It turns out that the semantics of such a view cannot be described by computations (i.e., graph transformations), but just by observations of computations of the global system. Such observations of computations cannot be represented by graph transformations in the usual sense because a local view may lack operations (productions) of the global system, so that state changes may be observed that do not have a cause in the local view. Therefore, the notion of graph transition is introduced as loose semantics for productions, where the production specifies only a lower bound to the activities that are to happen during application. Contrastingly, in the classical doublepushout approach to graph rewriting, productions are interpreted as complete descriptions of the transformations to be performed. For typed graph transformation systems a transition sequence semantics is developed, comprising all finite and infinite sequences of transitions in a system. Moreover, this semantics is shown to be compositional w.r.t. the synchronization of views.}},
  author       = {{Ehrig, Hartmut and Heckel, Reiko and Padberg, Julia and Taentzer, Gabriele and Wolter, Uwe and Corradini, Andrea and Engels, Gregor}},
  booktitle    = {{Report on the Dagstuhl-Seminar 9637 on Graph Transformations in Computer Science}},
  number       = {{155}},
  pages        = {{11--12}},
  publisher    = {{Technical University of Berlin}},
  title        = {{{Synchronization of Views and Loose Semantics of Typed Graph Productions}}},
  year         = {{1996}},
}

@inproceedings{7835,
  author       = {{Heckel, Reiko}},
  booktitle    = {{Report on the Dagstuhl-Seminar 9637 on Graph Transformations in Computer Science}},
  number       = {{155}},
  pages        = {{12--13}},
  publisher    = {{Technical University of Berlin}},
  title        = {{{Behavioral Constraints for Loose Graph Transformation Systems}}},
  year         = {{1996}},
}

@inproceedings{7836,
  abstract     = {{A large industrial process, software maintenance, has been modelled by using the process modelling language SOCCA. The paper reports about the experiences with this trial. In particular, feasibility, expressiveness, quality and the overall benefits of a formal SOCCA model are discussed and compared to the formerly existing informal process description. In order to illustrate the results, a well chosen process model fragment from the larger model is outlined in detail. It addresses in particular the human-intensive cooperation within the process and shows the seamless combination of technical components and human agent components in the SOCCA model. The main conclusions from this trial are that formal SOCCA models are suited to model realistic industrial processes and that due to an intrinsic modular structure of a SOCCA model, even huge models remain reasonably readable and understandable}},
  author       = {{de Bunje, Tineke and Engels, Gregor and Groenewegen, Luuk and Matsinger, Aart and Rijnbeek, Martin}},
  booktitle    = {{Proceedings of the Fourth International Conference on the Software Process (ICSP 1996), Brighton (UK)}},
  pages        = {{13--26}},
  publisher    = {{IEEE Computer Society}},
  title        = {{{Industrial maintenance modelled in SOCCA: an experience report}}},
  doi          = {{http://dx.doi.org/10.1109/ICSP.1996.565021}},
  year         = {{1996}},
}

@inproceedings{7837,
  abstract     = {{In order to manage the complexity of large system specifications, they have to be decomposed into subspecifications. Each subspecification describes a certain part of the system. This might be a certain aspect, like the data, dynamic, or functional aspect, as it is known from object-oriented modelling techniques. Or it might be a certain view onto the system, as it is known from database modelling techniques. The talk motivates the usage of views in graph grammarbased specifications. First, the usage of typed graph grammars inherently ensures an integration of the data and the functional aspect within a view. Second, it is explained that it is not appropriate in case of views to have a fixed semantics. The standard fixed semantics, i.e. a graph transformation system, has to be relaxed to a loose semantics, i.e. a graph transition system. This reflects the idea that a view models only a part of the complete system. Other views may overlap a view with respect to data or functionality. A complete system specification is yielded by exploiting the approach of cooperative parallel composition of graph grammars (see talk by Leila Ribeiro).}},
  author       = {{Engels, Gregor and Ehrig, Hartmut and Heckel, Reiko and Taentzer, Gabriele and Corradini, Andrea}},
  booktitle    = {{Report on Dagstuhl-Seminar 9637 on Graph Transformations in Computer Science}},
  pages        = {{11}},
  publisher    = {{Technical University of Berlin}},
  title        = {{{A View-Based Approach to System Modelling}}},
  volume       = {{155}},
  year         = {{1996}},
}

@inproceedings{7838,
  abstract     = {{Object-oriented specification mechanisms have become famous for modelling structure and behaviour together in terms of autonomous objects communicating via message passing. However, whereas most object-oriented specification methods are strong in modelling the local behaviour of single objects, they fall short on modelling the coordinated behaviour and collaboration of several objects together The aim of this paper is to contribute to fill this gap. The paper reports on concepts, language constructs, and experiences with three collaboration formalisms in the area of object-oriented specifications.}},
  author       = {{Engels, Gregor and Groenewegen, Luuk and Kappel, Gerti}},
  booktitle    = {{Proceedings of IFIP World Conference on IT Tools (1996), Canberra (Australia)}},
  pages        = {{437--452}},
  publisher    = {{Chapman & Hall}},
  title        = {{{Object-oriented specification of coordinated collaboration}}},
  year         = {{1996}},
}

@techreport{8197,
  abstract     = {{The framework of graph transformation combines the potentials and advantages of both, graphs and rules, into a single computational paradigm. In this paper we survey recent developments in applying graph transformation as a rule-based framework for the specification and development of systems, languages, and tools. After presenting the basic features of graph transformation, we discuss a spectrum of applications including the evaluation of functional expressions, the specification of an interactive graphical tool, an example specification for abstract data types, and the definition of a visual database query language. The case studies indicate the need for a graph transformation language that provides suitable structuring principles and is independent of a particular graph transformation approach. To this end, we sketch the basic features of the new graph- and rule-centered language Grace, currently under development, that permits systematic and structured specification and programming based on graph transformation.}},
  author       = {{Andries, Marc and Engels, Gregor and Habel, Annegret and Hoffmann, Berthold and Kreowski, Hans-Jörg and Kuske, Sabine and Plump, Detlef and Schürr, Andy and Taentzer, Gabriele}},
  publisher    = {{University of Bremen, Department of Mathematics and Computer Science}},
  title        = {{{Graph Transformation for Specification and Programming}}},
  year         = {{1996}},
}

@techreport{8198,
  author       = {{Busatto, Giorgio and Engels, Gregor}},
  publisher    = {{Vakgroep Informatica, Rijksuniversiteit Leiden}},
  title        = {{{Definition of an Encapsulated Hierarchical Graph Data Model: Static Aspects, Part 1.}}},
  year         = {{1996}},
}

@techreport{8199,
  author       = {{Engels, Gregor and Groenewegen, Luuk and Kappel, Gerti}},
  publisher    = {{Vakgroep Informatica, Rijksuniversiteit Leiden}},
  title        = {{{Object-oriented Specification of Coordinated Collaboration}}},
  year         = {{1996}},
}

@techreport{8200,
  author       = {{Heckel, Reiko and Corradini, Andrea and Ehrig, Hartmut and Löwe, Michael}},
  title        = {{{Horizontal and Vertical Structuring of Typed Graph Transformation Systems}}},
  year         = {{1996}},
}

@inproceedings{8271,
  author       = {{de Bunje, Tineke and Engels, Gregor and Groenewegen, Luuk and Heus, Michael and Matsinger, Aart}},
  booktitle    = {{Proceedings of the Workshop on Software Process Technology (EWSPT 1996), Nancy (France)}},
  pages        = {{183--187}},
  publisher    = {{Springer}},
  title        = {{{Towards Measurable Process Models}}},
  doi          = {{http://dx.doi.org/10.1007/BFb0017743}},
  volume       = {{1149}},
  year         = {{1996}},
}

@inproceedings{8272,
  abstract     = {{The paper presents a conceptual framework for a module concept for graph transformation systems from a software engineering as well as from a theoretical point of view. The basic idea is to reuse concepts, which are known within or without the graph grammar field, to structure large specifications. These are the concept of distributed graph transformation systems, the concept of inheritance of specifications, and the import-export-interface concept. All these concepts are presented in a uniform framework based on the syntactical notion of a graph class specification and its semantics given by a graph transformation system. This is the basis for an explicit integration of these concepts and a corresponding specification language, to be discussed in a subsequent paper.}},
  author       = {{Ehrig, Hartmut and Engels, Gregor}},
  booktitle    = {{Selected papers from the 5th International Workshop on Graph Gramars and Their Application to Computer Science, Williamsburg, VA (USA)}},
  pages        = {{137--154}},
  publisher    = {{Springer}},
  title        = {{{Pragmatic and Semantic Aspects of a Module Concept for Graph Transformation Systems}}},
  volume       = {{1073}},
  year         = {{1996}},
}

@inproceedings{8273,
  author       = {{Engels, Gregor and Zamperoni, Andreas}},
  booktitle    = {{Proceedings of the Workshop on Requirements Engineering in a Changing World (satellite event of the Conference on Advanced Information Systems Engineering (CAISE 1996)), Crete (Greece)}},
  pages        = {{42--44}},
  title        = {{{Comprehensive Support for Change: Generic, Multi-dimensional (Software) Engineering Frameworks (position paper)}}},
  year         = {{1996}},
}

@inproceedings{8274,
  abstract     = {{By means of a special sofnvare process model component we have been successful in specifring somare process model evolution, This component also handles much reuse of software process model fragments. To handle the reuse of the software as it is being produced by a software process, another extra component can be added to the model for that software process. It is argued why this extra component is comparable to the special component for evolution.}},
  author       = {{Groenewegen, Luuk and Engels, Gregor}},
  booktitle    = {{Proceedings of the 10th International Software Process Workshop (ISPW 1996), Ventron (France)}},
  pages        = {{68}},
  publisher    = {{IEEE Computer Society}},
  title        = {{{Reuse of Software Process Fragments is Reuse of Software, too}}},
  year         = {{1996}},
}

@inproceedings{8275,
  abstract     = {{This extended abstract describes a mechanism to automatically incorporate safety requirements into operational specifications written in Z. For every individual operation the global (i.e. operation independent) safety invariants are transformed into a predicate which is used to extend the original precondiction of the operation. The operation constructed this way shows the same beavior as the original one whenever its post state satisfies the invariant. Otherwise it refuses to do anything. The construction of the precondition can be carried out automatically and a corresponding tool development is in progress.}},
  author       = {{Heckel, Reiko and Conrad, Mirko and Egger, Gottfried and Hiemer, Jörg}},
  booktitle    = {{Proceedings of the Workshop on Tools for System Development and Verifcation}},
  pages        = {{70--83}},
  publisher    = {{Shaker Verlag}},
  title        = {{{Automatic Integration of Safety Invariants into Z Specifications}}},
  volume       = {{1}},
  year         = {{1996}},
}

@article{7404,
  author       = {{Habel, Annegret and Heckel, Reiko and Taentzer, Gabriele}},
  journal      = {{Fundamenta Informaticae}},
  number       = {{3,4}},
  pages        = {{287--313}},
  title        = {{{Graph Grammars with Negative Application Conditions}}},
  volume       = {{26}},
  year         = {{1996}},
}

@article{7405,
  author       = {{Heckel, Reiko and Corradini, Andrea and Ehrig, Hartmut and Löwe, Michael}},
  journal      = {{Mathematical Structures in Computer Science}},
  number       = {{6}},
  pages        = {{613--648}},
  title        = {{{Horizontal and Vertical Structuring of Typed Graph Transformation Systems}}},
  volume       = {{6}},
  year         = {{1996}},
}