Petri net modules in the transformation-based component framework

AbstractComponent-based software engineering needs to be backed by thorough formal concepts and modeling techniques. This paper combines two concepts introduced independently by the two authors in previous papers. On one hand, the concept of Petri net modules introduced at IDPT 2002 in Padberg [J. Padberg, Petri net modules, Journal on Integrated Design and Process Technology 6 (4) (2002) 105–120], and on the other hand a generic component framework for system modeling introduced at FASE 2002 in Ehrig et al. [H. Ehrig, F. Orejas, B. Braatz, M. Klein, M. Piirainen, A generic component concept for system modeling, in: Proceedings of FASE ’02, Lecture Notes in Computer Science, vol. 2306, Springer, 2002]. First we develop a categorical formalization of the transformation based approach to components that is based on pushouts. This is the frame in which we show that Petri net modules can be considered as an instantiation of the generic component framework. This allows applying the transformation based semantics and compositionality result of the generic framework to Petri net modules. In addition to general Petri net modules we introduce Petri net modules preserving safety properties which can be considered as another instantiation of pushout based formalization of the generic framework

A graph-semantics of business configurations

In this paper we give graph-semantics to a fundamental part of the semantics of the service modeling language SRML. To achieve this goal we develop a new graph transformation system for what we call 2-level symbolic graphs. These kind of graphs extend symbolic graphs with a simple 2-level hierarchy that can be generalized to arbitrary hierarchies. We formalize the semantics using this new graph transformation system using a simple example of a trip booking agent.Postprint (published version

Reusable Launch Vehicle Design Implications for Regeneration Time

In last few years, the Air Force Research Laboratory sponsored several research projects on a Reusable Launch Vehicles (RLV) whose design, operation, and logistics requirements are intended to be much simpler than for the Space Shuttle. As a part of these efforts, previous researchers developed a model that simulated the post-landing, ground maintenance and prelaunch operations of a RLV in order to evaluate how its design parameters affect the logistics operations. The next logical step is to investigate the effects and interactions of all factors used in the existing simulation model in a single experiment that considers the huge number of possible design characteristics’ combinations discovered in the previous studies as well as varying resources such as manpower, ground support equipment and facilities. The goal of this research is to recommend to the AFRL a preferred design strategy that could minimize the resource requirements in terms of equipment and manpower as well as turnaround time of logistics operations. In order to achieve this goal, this study identifies significant effects of the RLV\u27s design characteristics by utilizing the AFRL’s MILEPOST discrete-event simulation model in a systematic design of experiment (DOE) approach. In addition, it assesses the impact of varying resources (manpower, ground support equipment and fleet size) on departure availability. The results of this research is intended to provide the AFRL with valuable and timely information about the combinations of selected RLV design characteristics which could assist in directing efforts in research and development of the future space vehicle

04241 Abstracts Collection -- Graph Transformations and Process Algebras for Modeling Distributed and Mobile Systems

Recently there has been a lot of research, combining concepts of process algebra with those of the theory of graph grammars and graph transformation systems. Both can be viewed as general frameworks in which one can specify and reason about concurrent and distributed systems. There are many areas where both theories overlap and this reaches much further than just using graphs to give a graphic representation to processes. Processes in a communication network can be seen in two different ways: as terms in an algebraic theory, emphasizing their behaviour and their interaction with the environment, and as nodes (or edges) in a graph, emphasizing their topology and their connectedness. Especially topology, mobility and dynamic reconfigurations at runtime can be modelled in a very intuitive way using graph transformation. On the other hand the definition and proof of behavioural equivalences is often easier in the process algebra setting. Also standard techniques of algebraic semantics for universal constructions, refinement and compositionality can take better advantage of the process algebra representation. An important example where the combined theory is more convenient than both alternatives is for defining the concurrent (noninterleaving), abstract semantics of distributed systems. Here graph transformations lack abstraction and process algebras lack expressiveness. Another important example is the work on bigraphical reactive systems with the aim of deriving a labelled transitions system from an unlabelled reactive system such that the resulting bisimilarity is a congruence. Here, graphs seem to be a convenient framework, in which this theory can be stated and developed. So, although it is the central aim of both frameworks to model and reason about concurrent systems, the semantics of processes can have a very different flavour in these theories. Research in this area aims at combining the advantages of both frameworks and translating concepts of one theory into the other. The Dagsuthl Seminar, which took place from 06.06. to 11.06.2004, was aimed at bringing together researchers of the two communities in order to share their ideas and develop new concepts. These proceedings4 of the do not only contain abstracts of the talks given at the seminar, but also summaries of topics of central interest. We would like to thank all participants of the seminar for coming and sharing their ideas and everybody who has contributed to the proceedings

Understanding and supporting pricing decisions using multicriteria decision analysis: an application to antique silver in South Africa

This dissertation presents an application of multicriteria decision analysis to understand and support pricing decisions in fields where goods are unique and described by their characteristics. The specific application area of this research is antique silver objects, where a complete iteration of the multicritia decision process is performed. This includes two problem structurings using SODA which provide rich detail into this application area. Multi-attribute additive models are constructed, with attribute partial value functions elicited using different methods: directly (bisection methods), indirectly (MACBETH and linear interpolation) and with discrete choice experiments. The applicability and advantages of each method is discussed. Additionally, an open source R package to implement the design of discrete choice experiments is created. The multi-attribute models provide key insights into decision maker's reasoning for price; and contrasting different decision maker's models explains the market. A risk adverse relationship between multicriteria model score and price is characterised and various inverse utility functions investigated. Two decision support systems are fully developed to address the needs of Cape silver decision makers in South Africa

A formal denotation of complex systems: how to use algebraic refinement to deal with complexity of systems

Abstract A mathematical denotation is proposed for the notion of complex software systems whose behavior is specified by rigorous formalisms. Complex systems are described in a recursive way as an interconnection of sub-systems by means of architectural connectors. In order to consider the largest family of specification formalisms and architectural connectors, this denotation is essentially formalism, specification and connector-independent. For this, we build our denotation on Goguen's institution theory. We then denote in this abstract framework, system complexity by the notion of property emergence and give some conditions to establish when a system is or is not complex. Moreover, we define a refinement theory to deal with the complexity of systems in our generic framework. Indeed, one of the main problem encountered when dealing with complex system is the problem of emergent property detection. In this paper, we propose to use the algebraic refinement technics as a basic incremental method to simplify the emergent property detection. Finally, we illustrate our approach on the formalism classicaly used to specify biological processes: R. Thomas 's genetic regulatory networks (GRNs) over the temporal logic CTL and through the connector of sub-GRN embedding.

Patterns, Information, and Causation

This paper articulates an account of causation as a collection of information-theoretic relationships between patterns instantiated in the causal nexus. I draw on Dennett’s account of real patterns to characterize potential causal relata as patterns with specific identification criteria and noise tolerance levels, and actual causal relata as those patterns instantiated at some spatiotemporal location in the rich causal nexus as originally developed by Salmon. I develop a representation framework using phase space to precisely characterize causal relata, including their degree of counterfactual robustness, causal profiles, causal connectivity, and privileged grain size. By doing so, I show how the philosophical notion of causation can be rendered in a format that is amenable for direct application of mathematical techniques from information theory such that the resulting informational measures are causal informational measures. This account provides a metaphysics of causation that supports interventionist semantics and causal modeling and discovery techniques

A Framework of hierarchical graphs and its application to the semantics of SRML

Hierarchical grapsh or, in general, hierarchical graph structures are needed when describing visual models at different levels of abstraction. This is the case of the semantic model of SRML, the service modeling language of the european project SENSORIA. In particular, the state model of this language is considered at two level of abstraction. Roughly, at the lowest level, a state configuration is a graph consisting of interconnected components and, at the highest level, business configurations are graphs consisting of interconnected activities, where each activity is a graph of components. Then, a state configuration is the flattening of the corresponding business configuration. Following these ideas, in this paper, we present a new framework of hierarchical graphs, showing that it is m-adhesive. Then we show how this framework can be used to define (part of) a graph transformation semantics of SRML.Postprint (published version