@inproceedings{LewerentzSimon, author = {Lewerentz, Claus and Simon, Frank}, title = {Metrics-based 3D Visualization of Large Object-Oriented Programs}, abstract = {In this paper a new approach for a metrics based software visualization is presented which supports an efficient and effective quality assessment of large object-oriented software systems. It is based on the combination of software metrics data with structure information to form a virtual information space. This information space is visualized using 3D graph structures that allow to represent in a uniform way many aspects and views on it. The layout approach for these graphs uses a generic similarity measure to calculate geometric distances between the graph nodes and a force-directed mapping into 3D space. A particular strength of the approach is that the resulting geometrical structures can be well interpreted with respect to the architecture and design quality of the analysed software. Such 3D visualizations have been used successfully in several case studies for the quality assessment of industrial C++/Java projects.}, language = {en} } @phdthesis{Beyer, author = {Beyer, Dirk}, title = {Formale Verifikation von Realzeit-Systemen mittels Cottbus Timed Automata}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-000000258}, language = {de} } @inproceedings{SimonSteinbruecknerLewerentz, author = {Simon, Frank and Steinbr{\"u}ckner, Frank and Lewerentz, Claus}, title = {Anpaßbare, explorierbare virtuelle Informationsr{\"a}ume zur Qualit{\"a}tsbewertung großer Software-Systeme}, series = {3. Workshop Software Reengineering, Bad Honnef, 10./11. Mai 2001}, booktitle = {3. Workshop Software Reengineering, Bad Honnef, 10./11. Mai 2001}, publisher = {Univ., Inst. f{\"u}r Informatik}, address = {Koblenz-Landau}, language = {de} } @inproceedings{BeyerHeinig, author = {Beyer, Dirk and Heinig, Andy}, title = {Different Strategies for BDD-based Reachability Analysis of Timed Automata}, series = {Proceedings of the 2nd IEEE/IFIP Joint Workshop on Formal Specifications of Computer-Based Systems (FSCBS 2001, Washington, D.C., April 2001)}, booktitle = {Proceedings of the 2nd IEEE/IFIP Joint Workshop on Formal Specifications of Computer-Based Systems (FSCBS 2001, Washington, D.C., April 2001)}, editor = {Rozenblit, Jerzy and Sveda, Miroslav and Rattray, Charles}, address = {Stirling}, pages = {89 -- 98}, language = {en} } @inproceedings{BeyerLewerentzSimon, author = {Beyer, Dirk and Lewerentz, Claus and Simon, Frank}, title = {Impact of Inheritance on Metrics for Size, Coupling, and Cohesion in Object Oriented Systems}, series = {New approaches in software measurement, 10th international workshop, proceedings, IWSM 2000, Berlin, Germany, October 4 - 6, 2000}, booktitle = {New approaches in software measurement, 10th international workshop, proceedings, IWSM 2000, Berlin, Germany, October 4 - 6, 2000}, editor = {Abran, Alain and Dumke, Reiner}, publisher = {Springer}, address = {Berlin [u.a.]}, isbn = {3-540-41727-3}, pages = {1 -- 17}, language = {en} } @inproceedings{BeyerNoack, author = {Beyer, Dirk and Noack, Andreas}, title = {Efficient Verification of Timed Automata using BDDs}, series = {FMICS 2001, Formal methods for industrial critical systems, proceedings, International workshop on formal methods for industrial critical systems 6, 16 - 17 July 2001, Paris}, booktitle = {FMICS 2001, Formal methods for industrial critical systems, proceedings, International workshop on formal methods for industrial critical systems 6, 16 - 17 July 2001, Paris}, editor = {Ultes-Nitsche, Ulrich and Gnesi, Stefania}, publisher = {INRIA}, address = {Rocquencourt}, isbn = {2-7261-1187-4}, pages = {95 -- 113}, language = {en} } @inproceedings{BeyerRust, author = {Beyer, Dirk and Rust, Heinrich}, title = {Timed Automata Formal Definition and Semantics}, series = {Joint Workshop on Formal Specification of Computer-Based Systems, Washington DC, USA, April 20, 2001}, booktitle = {Joint Workshop on Formal Specification of Computer-Based Systems, Washington DC, USA, April 20, 2001}, editor = {Rattray, Charles and Sveda, Miroslav and Rozenblit, Jerzy}, publisher = {University of Stirling, Dept. of Computing Science and}, address = {Stirling}, pages = {75 -- 87}, language = {en} } @inproceedings{Beyer, author = {Beyer, Dirk}, title = {Efficient Reachability Analysis and Refinement Checking of Timed Automata using BDDs}, series = {Correct hardware design and verification methods, 11th IFIP WG 10.5 advanced research working conference, proceedings, CHARME 2001, Livingston, Scotland, UK, September 4 - 7, 2001}, booktitle = {Correct hardware design and verification methods, 11th IFIP WG 10.5 advanced research working conference, proceedings, CHARME 2001, Livingston, Scotland, UK, September 4 - 7, 2001}, editor = {Margaria, Tiziana and Melham, Tom}, publisher = {Springer}, address = {Berlin [u.a.]}, isbn = {3-540-42541-1}, pages = {86 -- 91}, language = {en} } @inproceedings{Beyer, author = {Beyer, Dirk}, title = {Improvements in BDD-based Reachability Analysis of Timed Automata}, series = {Formal methods for increasing software productivity, proceedings, FME 2001, International Symposium of Formal Methods Europe, Berlin, Germany, March 12 - 16, 2001}, booktitle = {Formal methods for increasing software productivity, proceedings, FME 2001, International Symposium of Formal Methods Europe, Berlin, Germany, March 12 - 16, 2001}, editor = {Zave, Pamela and Oliveira, Jos{\´e} Nuno}, publisher = {Springer}, address = {Berlin [u.a.]}, isbn = {3-540-41791-5}, pages = {318 -- 343}, language = {en} } @inproceedings{LewerentzRust, author = {Lewerentz, Claus and Rust, Heinrich}, title = {Die Rolle der Reflexion in Software-Praktika}, series = {Software Engineering im Unterricht der Hochschulen, SEUH 7, Z{\"u}rich 2001}, booktitle = {Software Engineering im Unterricht der Hochschulen, SEUH 7, Z{\"u}rich 2001}, editor = {Lichter, Horst and Glinz, Martin}, publisher = {dpunkt-Verlag}, address = {Heidelberg}, isbn = {3-89864-106-6}, pages = {73 -- 88}, language = {de} } @inproceedings{RustLewerentz, author = {Rust, Heinrich and Lewerentz, Claus}, title = {A Model for Analyzing Measurement Based Feedback Loops in Software Development Projects}, series = {Advances in learning software organizations, third international workshop, proceedings, LSO 2001, Kaiserslautern, Germany, September 12 - 13, 2001}, booktitle = {Advances in learning software organizations, third international workshop, proceedings, LSO 2001, Kaiserslautern, Germany, September 12 - 13, 2001}, editor = {Althoff, Klaus-Dieter}, publisher = {Springer}, address = {Berlin [u.a.]}, isbn = {3-540-42574-8}, pages = {135 -- 149}, language = {en} } @inproceedings{SimonSteinbruecknerLewerentz, author = {Simon, Frank and Steinbr{\"u}ckner, Frank and Lewerentz, Claus}, title = {Metrics Based Refactoring}, series = {Proceedings of the Fifth European Conference on Software Maintenance and Reengineering, 14 - 16 March 2001, Lisbon, Portugal}, booktitle = {Proceedings of the Fifth European Conference on Software Maintenance and Reengineering, 14 - 16 March 2001, Lisbon, Portugal}, editor = {Sousa, Pedro}, publisher = {IEEE Computer Society}, address = {Los Alamitos, Calif. [u.a.]}, isbn = {0-7695-1028-0}, pages = {30 -- 38}, language = {en} } @inproceedings{BeyerLewerentzNoack, author = {Beyer, Dirk and Lewerentz, Claus and Noack, Andreas}, title = {Rabbit: A Tool for BDD-based Verification of Real-Time Systems}, series = {Computer aided verification, 15th international conference, proceedings, CAV 2003, Boulder, CO, USA, July 8 - 12, 2003}, booktitle = {Computer aided verification, 15th international conference, proceedings, CAV 2003, Boulder, CO, USA, July 8 - 12, 2003}, editor = {Hunt, Warren A.}, publisher = {Springer}, address = {Berlin [u.a.]}, isbn = {3-540-40524-0}, pages = {122 -- 125}, abstract = {This paper gives a short overview of a model checking tool for real-time systems. The modeling language are timed automata extended with concepts for modular modeling. The tool provides reachability analysis and refinement checking, both implemented using the data structure BDD. Good variable orderings for the BDDs are computed from the modular structure of the model and an estimate of the BDD size. This leads to a significant performance improvement compared to the tool RED and the BDD-based version of Kronos.}, language = {en} } @inproceedings{BeyerNoack, author = {Beyer, Dirk and Noack, Andreas}, title = {Can Decision Diagrams Overcome State Space Explosion in Real-Time Verification?}, series = {Formal techniques for networked and distributed systems - FORTE 2003, 23rd IFIP WG 6.1, international conference, Berlin, Germany, September 29 - October 2, 2003, proceedings}, booktitle = {Formal techniques for networked and distributed systems - FORTE 2003, 23rd IFIP WG 6.1, international conference, Berlin, Germany, September 29 - October 2, 2003, proceedings}, editor = {K{\"o}nig, Hartmut}, publisher = {Springer}, address = {Berlin [u.a.]}, isbn = {3-540-20175-0}, pages = {193 -- 208}, abstract = {In this paper we analyze the efficiency of binary decision diagrams (BDDs) and clock difference diagrams (CDDs) in the verification of timed automata. Therefore we present analytical and empirical complexity results for three communication protocols. The contributions of the analyses are: Firstly, they show that BDDs and CDDs of polynomial size exist for the reachability sets of the three protocols. This is the first evidence that CDDs can grow only polynomially for models with non-trivial state space explosion. Secondly, they show that CDD-based tools, which currently use at least exponential space for two of the protocols, will only find polynomial-size CDDs if they use better variable orders, as the BDD-based tool Rabbit does. Finally, they give insight into the dependency of the BDD and CDD size on properties of the model, in particular the number of automata and the magnitude of the clock values.}, language = {en} } @inproceedings{Noack, author = {Noack, Andreas}, title = {An Energy Model for Visual Graph Clustering}, series = {Graph Drawing, 11th International Symposium, GD 2003, Perugia, Italy, Sep. 21 - 24, 2003}, booktitle = {Graph Drawing, 11th International Symposium, GD 2003, Perugia, Italy, Sep. 21 - 24, 2003}, editor = {Liotta, Guiseppe}, publisher = {Springer Verlag}, address = {Berlin [u.a.]}, isbn = {3-540-20831-3}, pages = {425 -- 436}, abstract = {We introduce an energy model whose minimum energy drawings reveal the clusters of the drawn graph. Here a cluster is a set of nodes with many internal edges and few edges to nodes outside the set. The drawings of the best-known force and energy models do not clearly show clusters for graphs whose diameter is small relative to the number of nodes. We formally characterize the minimum energy drawings of our energy model. This characterization shows in what sense the drawings separate clusters, and how the distance of separated clusters to the other nodes can be interpreted}, language = {en} } @inproceedings{Rust, author = {Rust, Heinrich}, title = {A Non-standard Approach to Operational Semantics for Timed Systems}, series = {Abstract state machines 2003, advances in theory and practice, 10th international workshop, proceedings, ASM 2003, Taormina, Italy, March 3 - 7, 2003}, booktitle = {Abstract state machines 2003, advances in theory and practice, 10th international workshop, proceedings, ASM 2003, Taormina, Italy, March 3 - 7, 2003}, editor = {B{\"o}rger, Egon}, publisher = {Springer}, address = {Heidelberg [u.a.]}, isbn = {3-540-00624-9}, pages = {423 -- 424}, language = {en} } @inproceedings{LewerentzSimonSteinbrueckneretal., author = {Lewerentz, Claus and Simon, Frank and Steinbr{\"u}ckner, Frank and Breitling, H. and Lilienthal, C. and Lippert, M.}, title = {External Validation of a Metrics-Based Quality Assessment of the JWAM Framework}, series = {Software-Messung und -Bewertung, Tagungsband Workshop der GI-Fachgruppe 2.1.10, 10./11. September 2001 an der Universit{\"a}t Kaiserslautern}, booktitle = {Software-Messung und -Bewertung, Tagungsband Workshop der GI-Fachgruppe 2.1.10, 10./11. September 2001 an der Universit{\"a}t Kaiserslautern}, publisher = {Dt. Univ.-Verl.}, address = {Wiesbaden}, isbn = {3-8244-7592-8}, pages = {32 -- 49}, language = {en} } @incollection{BennickeLewerentz, author = {Bennicke, Marcel and Lewerentz, Claus}, title = {Towards Managing Software Architectures with Ontologies}, abstract = {Abstract. Software architectures are key enabling assets within organizationsthat develop complex software systems. Among other purposes,software architectures are useful to maintain intellectual control overa software product. We propose a method to continuously check theconsistency between a specified architecture model and structural informationreverse engineered from the code. We develop criteria that adesign language for architectures should fulfill and show that an ontologybased description has substantial benefits over the standard modelinglanguages MOF/UML/OCL. Using ontologies allows the explicitmodelling of architectural styles as well as concrete system structuresin a single architecture design language. The resulting specifications aremodular, compositional and evolvable. Using ontologies we can apply anontology reasoner to implement consistency checks. Our method integratespreviously separate checks such as checking for allowed dependenciesand coding style into a single framework and enables more powerfuland flexible analyses.}, language = {en} } @inproceedings{Steinbrueckner, author = {Steinbr{\"u}ckner, Frank}, title = {Coherent Software Cities : Supporting Comprehension of Evolving Software Systems}, series = {2010 IEEE International Conference on Software Maintenance (ICSM 2010), Timi{\c{s}}oara, Romania, 12 - 18 September 2010}, booktitle = {2010 IEEE International Conference on Software Maintenance (ICSM 2010), Timi{\c{s}}oara, Romania, 12 - 18 September 2010}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-4244-8630-4}, pages = {532 -- 533}, abstract = {Coherent Software Cities are a software visualization approach which adopts the city metaphor to support the comprehension of various aspects of evolving software systems. For this purpose, the approach implements a three-staged modeling chain yielding coherent sets of application specific visualizations. In this context, a new layout approach for software cities is presented, which explicitly takes development history into account. Its effects are twofold: First, evolution becomes visible in the layouts, which allows for supporting new application scenarios. Second, layouts evolve smoothly and stable during system evolution, which allows software cities to be used online, i.e. during ongoing system development and maintenance.}, language = {en} } @article{LewerentzRust, author = {Lewerentz, Claus and Rust, Heinrich}, title = {Software-Ingenieure als kompetente Teamworker}, series = {Softwaretechnik-Trends}, volume = {21}, journal = {Softwaretechnik-Trends}, number = {1}, issn = {0720-8928}, pages = {30 -- 35}, language = {de} }