13 research outputs found

    Zooming-out on Higraph-based diagrams: Syntactic and Semantic Issues

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    AbstractComputing system representations based on Harel's notion of hierarchical graph, or higraph, have become popular since the invention of Statecharts. Such hierarchical representations support a useful filtering operation, called “zooming-out”, which is used to manage the level of detail presented to the user designing or reasoning about a large and complex system. In the framework of (lightweight) category theory, we develop the mathematics of zooming e ut for higraphs with loose edges, formalise the transition semantics of such higraphs and conduct an analysis of the effect the operation of zooming out has on the semantic interpretations, as required for the soundness of reasoning arguments depending on zoom-out steps

    ONTOLOGY-ENABLED TRACEABILITY MODELS FOR ENGINEERING SYSTEMS DESIGN AND MANAGEMENT

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    This thesis describes new models and a system for satisfying requirements, and an architectural framework for linking discipline-specific dependencies through inter- action relationships at the ontology (or meta-model) level. In a departure from state-of-the-art traceability mechanisms, we ask the question: What design concept (or family of design concepts) should be applied to satisfy this requirement? Solu- tions to this question establish links between requirements and design concepts. The implementation of these concepts leads to the design itself. These ideas, and support for design-rule checking are prototyped through a series of progressively complicated applications, culminating in a case study for rail transit systems management

    Steps Towards a Method for the Formal Modeling of Dynamic Objects

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    Fragments of a method to formally specify object-oriented models of a universe of discourse are presented. The task of finding such models is divided into three subtasks, object classification, event specification, and the specification of the life cycle of an object. Each of these subtasks is further subdivided, and for each of the subtasks heuristics are given that can aid the analyst in deciding how to represent a particular aspect of the real world. The main sources of inspiration are Jackson System Development, algebraic specification of data- and object types, and algebraic specification of processes

    Constrained Planarity and Augmentation Problems

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    A clustered graph C=(G,T) consists of an undirected graph G and a rooted tree T in which the leaves of T correspond to the vertices of G=(V,E). Each vertex m in T corresponds to a subset of the vertices of the graph called ``cluster''. c-planarity is a natural extension of graph planarity for clustered graphs, and plays an important role in automatic graph drawing. The complexity status of c-planarity testing is unknown. It has been shown by Dahlhaus, Eades, Feng, Cohen that c-planarity can be tested in linear time for c-connected graphs, i.e., graphs in which the cluster induced subgraphs are connected. In the first part of the thesis, we provide a polynomial time algorithms for c-planarity testing of specific planar clustered graphs: Graphs for which - all nodes corresponding to the non-c-connected clusters lie on the same path in T starting at the root of T, or graphs in which for each non-connected cluster its super-cluster and all its siblings in T are connected, - for all clusters m G-G(m) is connected. The algorithms are based on the concepts for the subgraph induced planar connectivity augmentation problem, also presented in this thesis. Furthermore, we give some characterizations of c-planar clustered graphs using minors and dual graphs and introduce a c-planar augmentation method. Parts II deals with edge deletion and bimodal crossing minimization. We prove that the maximum planar subgraph problem remains NP-complete even for non-planar graphs without a minor isomorphic to either K(5) or K(3,3), respectively. Further, we investigate the problem of finding a minimum weighted set of edges whose removal results in a graph without minors that are contractible onto a prespecified set of vertices. Finally, we investigate the problem of drawing a directed graph in two dimensions with a minimal number of crossings such that for every node the incoming and outgoing edges are separated consecutively in the cyclic adjacency lists. It turns out that the planarization method can be adapted such that the number of crossings can be expected to grow only slightly for practical instances

    Design Recovery and Data Mining: A Methodology That Identifies Data-Cohesive Subsystems Based on Mining Association Rules.

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    Software maintenance is both a technical and an economic concern for organizations. Large software systems are difficult to maintain due to their intrinsic complexity, and their maintenance consumes between 50% and 90% of the cost of their complete life-cycle. An essential step in maintenance is reverse engineering, which focuses on understanding the system. This system understanding is critical to avoid the generation of undesired side effects during maintenance. The objective of this research is to investigate the potential of applying data mining to reverse engineering. This research was motivated by the following: (1) data mining can process large volumes of information, (2) data mining can elicit meaningful information without previous knowledge of the domain, (3) data mining can extract novel non-trivial relationships from a data set, and (4) data mining is automatable. These data mining features are used to help address the problem of understanding large legacy systems. This research produced a general method to apply data mining to reverse engineering, and a methodology for design recovery, called Identification of Subsystems based on Associations (ISA). ISA uses mined association rules from a database view of the subject system to guide a clustering process that produces a data-cohesive hierarchical subsystem decomposition of the system. ISA promotes object-oriented principles because each identified subsystem consists of a set of data repositories and the code (i.e., programs) that manipulates them. ISA is an automatic multi-step process, which uses the source code of the subject system and multiple parameters as its input. ISA includes two representation models (i.e., text-based and graphic-based representation models) to present the resulting subsystem decomposition. The automated environment RE-ISA implements the ISA methodology. RE-ISA was used to produce the subsystem decomposition of real-word software systems. Results show that ISA can automatically produce data-cohesive subsystem decompositions without previous knowledge of the subject system, and that ISA always generates the same results if the same parameters are utilized. This research provides evidence that data mining is a beneficial tool for reverse engineering and provides the foundation for defining methodologies that combine data mining and software maintenance

    Toward composing variable structure models and their interfaces: a case of intensional coupling definitions

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    In this thesis, we investigate a combination of traditional component-based and variable structure modeling. The focus is on a structural consistent specification of couplings in modular, hierarchical models with a variable structure. For this, we exploitintensional definitions, as known from logic, and introduce a novel intensional coupling definition, which allows a concise yet expressive specification of complex communication and interaction patterns in static as well as variable structure models, without the need to worryabout structural consistency.In der Arbeit untersuchen wir ein Zusammenbringen von klassischer komponenten-basierter und variabler Strukturmodellierung. Der Fokus liegt dabei auf der Spezifikation von strukturkonsistenten Kopplungen in modular-hierarchischen Modellen mit einer variablen Struktur. Dafür nutzen wir intensionale Definitionen, wie sie aus der Logik bekannt sind, und führen ein neuartiges Konzept von intensionalen Kopplungen ein, welches kompakte gleichzeitig ausdrucksstarke Spezifikationen von komplexen Kommunikations- und Interaktionsmuster in statischen und variablen Strukturmodellen erlaubt

    A framework for analyzing changes in health care lexicons and nomenclatures

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    Ontologies play a crucial role in current web-based biomedical applications for capturing contextual knowledge in the domain of life sciences. Many of the so-called bio-ontologies and controlled vocabularies are known to be seriously defective from both terminological and ontological perspectives, and do not sufficiently comply with the standards to be considered formai ontologies. Therefore, they are continuously evolving in order to fix the problems and provide valid knowledge. Moreover, many problems in ontology evolution often originate from incomplete knowledge about the given domain. As our knowledge improves, the related definitions in the ontologies will be altered. This problem is inadequately addressed by available tools and algorithms, mostly due to the lack of suitable knowledge representation formalisms to deal with temporal abstract notations, and the overreliance on human factors. Also most of the current approaches have been focused on changes within the internal structure of ontologies, and interactions with other existing ontologies have been widely neglected. In this research, alter revealing and classifying some of the common alterations in a number of popular biomedical ontologies, we present a novel agent-based framework, RLR (Represent, Legitimate, and Reproduce), to semi-automatically manage the evolution of bio-ontologies, with emphasis on the FungalWeb Ontology, with minimal human intervention. RLR assists and guides ontology engineers through the change management process in general, and aids in tracking and representing the changes, particularly through the use of category theory. Category theory has been used as a mathematical vehicle for modeling changes in ontologies and representing agents' interactions, independent of any specific choice of ontology language or particular implementation. We have also employed rule-based hierarchical graph transformation techniques to propose a more specific semantics for analyzing ontological changes and transformations between different versions of an ontology, as well as tracking the effects of a change in different levels of abstractions. Thus, the RLR framework enables one to manage changes in ontologies, not as standalone artifacts in isolation, but in contact with other ontologies in an openly distributed semantic web environment. The emphasis upon the generality and abstractness makes RLR more feasible in the multi-disciplinary domain of biomedical Ontology change management

    Foundations of Multi-Paradigm Modelling for Cyber-Physical Systems

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    This open access book coherently gathers well-founded information on the fundamentals of and formalisms for modelling cyber-physical systems (CPS). Highlighting the cross-disciplinary nature of CPS modelling, it also serves as a bridge for anyone entering CPS from related areas of computer science or engineering. Truly complex, engineered systems—known as cyber-physical systems—that integrate physical, software, and network aspects are now on the rise. However, there is no unifying theory nor systematic design methods, techniques or tools for these systems. Individual (mechanical, electrical, network or software) engineering disciplines only offer partial solutions. A technique known as Multi-Paradigm Modelling has recently emerged suggesting to model every part and aspect of a system explicitly, at the most appropriate level(s) of abstraction, using the most appropriate modelling formalism(s), and then weaving the results together to form a representation of the system. If properly applied, it enables, among other global aspects, performance analysis, exhaustive simulation, and verification. This book is the first systematic attempt to bring together these formalisms for anyone starting in the field of CPS who seeks solid modelling foundations and a comprehensive introduction to the distinct existing techniques that are multi-paradigmatic. Though chiefly intended for master and post-graduate level students in computer science and engineering, it can also be used as a reference text for practitioners
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