Julia Padberg

Hochschule für Angewandte Wissenschaften Hamburg | HAW · Department of Computer Science

Computer Science for Future (CS4F) is an initiative in the Department of Computer Science at HAW Hamburg. The aim of the initiative is a paradigm shift in the discipline of computer science, thus establishing sustainability goals as a primary leitmotif for teaching and research. The focus is on teaching since the most promising multipliers are the...

Hierarchical Petri nets allow a more abstract view and reconfigurable Petri nets model dynamic structural adaptation. In this contribution we present the combination of reconfigurable Petri nets and hierarchical Petri nets yielding hierarchical structure for reconfigurable Petri nets. Hierarchies are established by substituting transitions by subne...

The evolution in software and hardware systems from classical systems with rigid structures to open, dynamic, and flexible structures has inspired the extension of Petri nets to reconfiguration. The idea of reconfiguring Petri nets was launched in the early nineties and since then has been developed by several researchers at different levels of for...

Graph transformation or graph rewriting has been developed for nearly 50 years and has become a mature and manifold formal technique. Basically, rewrite rules are used to manipulate graphs. These rules are given by a left-hand side and a right-hand side graph and the application comprises matching the left-hand side and replacing it with the right-...

Concepts for structuring are fundamental to any modelling technique. Hierarchical graphs allow vertical structuring, where nodes or edges contain other nodes or subgraphs. There have been several suggestions to hierarchical graphs that differ in terms of the underlying graph type, the elements that are structured and the way the structuring is achi...

In this contribution we investigate several extensions of the powerset that comprise arbitrarily nested subsets, and call them superpower set. This allows the definition of graphs with possibly infinitely nested nodes. additionally we define edges that are incident to edges. Since we use coalgebraic constructions we refer to these graphs as corecur...

Model checking is a widely used technique to prove properties such as liveness, deadlock or safety for a given model. Here we introduce model checking of reconfigurable Petri nets. These are Petri nets with a set of rules for changing the net dynamically. We obtain model checking by converting reconfigurable Petri nets to specific Maude modules and...

In this paper we introduce additional control structures for reconfigurable Petri nets. The main contributions are inhibitor arcs and transition priorities for reconfigurable Petri nets. The first ensure that a marking can inhibit the firing of a transition. Inhibitor arcs allow a transition to fire only if the adjacent place is empty. Transition p...

Software systems are increasingly executed in dynamic infrastructures. These infrastructures are dynamic as they are themselves subject to change as they support various applications that may or may not share some of the resources. Dynamic software systems become more and more important , but are difficult to handle. Modeling and simulating dynamic...

In this paper we deal with additional control structures for decorated PT Nets. The main contribution are inhibitor arcs and priorities. The first ensure that a marking can inhibit the firing of a transition. Inhibitor arcs force that the transition may only fire when the place is empty. an order of transitions restrict the firing, so that an trans...

This paper introduces an approach to model checking of reconfigurable Petri nets. The main task is to flatten the two levels of dynamic behavior that reconfigurable nets provide, the firing of transitions on the one hand and the transformation of the nets on the other hand. We show how to translate a reconfigurable net into Maude modules. Maude's L...

Modeling and simulating dynamic systems require to represent their processes and the system changes within one model. To that effect, reconfigurable Petri nets consist of a place/transition net and a set of rules that can modify the Petri net. The application of a rule is based on finding a suitable match of the rule in the given net. This match is...

This paper introduces an approach to model checking of reconfigurable Petri nets. The main task is to flatten the two levels of dynamic behavior that reconfigurable nets provide, the firing of transitions on the one hand and the transformation of the nets on the other hand. We show how to translate a reconfigurable net into Maude modules. Maude's L...

Reconfigurable Petri nets are Petri nets together with rules for the dynamic change of the nets. We employ them for the formal modeling in the context of the Living Place Hamburg, a smart home that is an urban apartment serving as a laboratory for investigating different areas of ambient intelligence. The interaction of the resident and the smart h...

Reconfigurable Petri nets are Petri nets together with rules for the dynamic change of the nets. We employ them for the formal modeling in the context of the Living Place Hamburg, a smart home that is an urban apartment serving as a laboratory for investigating different areas of ambient intelligence. The interaction of the resident and the smart h...

In this contribution we present a tool for modeling and simulation with reconfigurable Petri nets. Taking the idea of algebraic graph transformations to marked Petri nets we obtain Petri nets whose net structure can be changed dynamically. The rule-based change of the net structure enables the adequate modeling of complex, dynamic structures as for...

Algebraic higher-order (AHO) net systems are Petri nets with place/ transition systems, i.e. place/transition nets with initial markings, and rules as tokens. In several applications, however, there is the need for explicit data modeling. The main idea of this paper is to introduce AHO net systems with high-level net systems and corresponding rules...

Algebraic higher-order (AHO) net systems are Petri nets with place/ transition systems, i.e. place/transition nets with initial markings, and rules as tokens. In several applications, however, there is the need for explicit data modeling. The main idea of this paper is to introduce AHO net systems with high-level net systems and corresponding rules...

The aim of this paper is to show how the generic approach to connector architectures, presented in the first part of this work, can be applied to a given modeling formalism to define architectural component and connector notions associated to that formalism. Starting with a review of the generic approach, in this second part of the paper we conside...

The aim of this paper is to present a generic framework for the modelling of componentbased systems using architectural connectors. More precisely, concepts of component, connector and architecture are presented in a formal generic way, which are independent of any semi-formal or formal modelling approach. The idea is that one could use this framew...

Mobile ad-hoc networks (manets) are networks of mobile devices that communicate with each other via wireless links without relying on an underlying infrastructure. To model workflows in manets adequately a formal technique is given by algebraic higher-order nets. For this modeling technique we here present a high-level net process semantics and res...

The intention of this paper is to extend the generic component framework presented at FASE 2002 (EOB+02) to allow component verification based on export-import implications. In the generic component framework components with explicit import, export interfaces and a body specification connected by embeddings and transformations provide hierarchical...

In this paper we extend our results concerning the layered architecture for modeling workflows in Mobile Ad-Hoc networks (MANETs) using algebraic higher order nets. MANETs are networks of mobile devices that communicate with each other via wireless links without relying on an underlying infrastructure. Workflows in \manets can be adequately modeled...

In emergency scenarios we can obtain a more effective coordination among team members constituting a mobile ad hoc network (MANET) through the use of reconfigurable systems. This means that cooperative work can be adequately modeled by low level and high level Petri nets with initial markings and the net structure can be adapted to new requirements...

Reconfigurable place/transition systems are Petri nets with initial markings and a set of rules which allow the modification of the net during runtime in order to adapt the net to new requirements. For the transformation of Petri nets in the double pushout approach, the categorical framework of adhesive high-level replacement systems has been insta...

The integration of two important categorical frameworks - namely adhesive High-Level Re- placement (HLR) systems and the generic component concept - yields a categorical approach to component transformation and refinement. The generic component concept is shown to be an adhesive HLR category, so rules and transformations as well as the correspondin...

Modelling the adaption of a system to a changing environment gets more and more important. Application areas cover e.g. computer supported cooperative work, multi agent systems, dynamic process mining or mobile networks. One approach to combine formal modelling of dynamic systems and controlled model adaption are Petri net transformations. The main...

In this paper we extend our results (as given in (PHE+07)) concerning the layered architecture for modeling workflows in Mobile Ad-Hoc NETworks (MANETs) using algebraic higher order nets (AHO nets). MANETs are networks of mobile devices that communicate with each other via wireless links with- out relying on an underlying infrastructure. Workflows...

This paper introduces negative application conditions for reconfigurable place/transition nets. These are Petri nets together with a set of rules that allow changing the net and its marking dynamically. Negative application conditions are a control structure that prohibits the application of a rule if certain structures are already existent. We mot...

In emergency scenarios we can obtain a more ef- fective coordination among team members constitut- ing a mobile ad hoc network (MANET) through the use of reconfigurable systems. This means that coopera- tive work can be adequately modeled by low level and high level Petri nets with initial markings and the net structure can be adapted to new requir...

This paper introduces the modelling of discrete event based system and the verification of their properties using Petri net components. It is particularly interesting to apply a component based verification approach in order to hierarchically structure Petri nets and to verify their properties component-wise. Here, a new theoretical notion is exemp...

The intention of this paper is to extend the generic component framework to partial composition. Basic Ideas of partial composition were introduced in [EM90] but we additionally want to allow component verification based on export-import implications. Import-Export implications relate sentences of the import stating what the component requires to s...

Reconfigurable place/transition systems are Petri nets with initial markings and a set of rules which allow the modification of the net during runtime in order to adapt the net to new requirements of the envi- ronment. In this paper we use transformation rules for place/transition systems in the sense of the double pushout approach for graph trans-...

The paper introduces an abstract framework for the specification of components with multiple require and provide interfaces that allows the specification of multiple access to a single provide interface. This framework can be regarded as a generalization of abstract hierarchical and connector-based component specification approaches. The main ideas...

In this paper we present a layered architecture for modeling workflows in Mobile Ad-Hoc NETworks (manets) using algebraic higher order nets (aho nets). manets are networks of mobile devices that communicate with each other via wireless links without relying on an underlying infrastructure, e.g. in emergency scenarios, where an effective coordinatio...

Mobile Ad-hoc NETworks (MANETs) consist of mobile nodes which communicate with each other independently from a stable infrastructure, while the topology of the network constantly changes depending on the current position of the nodes and their availability. Unfortunately there are almost no approaches so far for the modeling and the analysis of tho...

In this contribution we suggest a method for the component-based verification based on Petri nets. Petri net components are extended with import-export implications. These can be expressed by temporal logic formulae. The satisfaction of these implications guarantees the export statement given in the export interface independently of the component's...

Mobile Ad-hoc NETworks (MANETs) consist of mobile nodes which communicate with each other independently from a stable infrastructure, while the topology of the network constantly changes depending on the current position of the nodes and their availability. Unfortunately there are almost no approaches so far for the modeling and the analysis of tho...

Reconfigurable place/transition systems are Petri nets with initial markings and a set of rules which allow the mod- ification of the net during runtime in order to adapt the net to new requirements. For the transformation of Petri nets, adhesive high-level replacement systems have been recentl y introduced as a new categorical framework in the dou...

Motivated by the work which has been done for Petri-nets, the paper presents a categorical approach to graph grammars in the large. In the large means, that we define categories of graph grammars, graph transition systems, and graph derivation systems which embody the notion grammar, direct derivation, and derivation, respectively, as they are defi...

Adhesive high-level replacement (HLR) systems are introduced as a new categorical framework for graph transformation in the double pushout (DPO) approach, which combines the well-known concept of HLR systems with the new concept of adhesive categories introduced by Lack and Sobocinacute;ski. In this paper we show that most of the HLR properties, wh...

The Workshop on Petri Nets and Graph Transformations, which is currently at its second edition, is focussed on the mutual relationship between two prominent specification formalisms for concurrency and distribution, namely Petri nets and graph transformation systems. It belongs to the folklore that Petri nets can be seen as rewriting systems over (...

Our approach of rule-based refinement1provides a formal description for the stepwise system development based on Petri nets. Rules with a left-hand and a right-hand side allow replacing subnets in a given algebraic high-level net system. The extension of these rules supports the preservation of system properties. In this paper we extend the preserv...

Component-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 an...

The aim of this paper is an introduction to the area of Petri net transformations, a rule-based approach for dynamic changes of the net structure of Petri nets. This is especially important for the stepwise construction of Petri nets in the sense of the software development process in software engineering. The concept of Petri net transformations i...

Petri nets, well established as a fundamental model of concurrency and as a specification technique for distributed systems, are revisited from an algebraic point of view. In a first step Petri nets can be considered as monoids with well-defined algebraic semantics. Secondly they can be combined with algebraic specifications leading to the concept...

Petrinetz-Module sind eine formale Komponententechnik, die verschieden Kompositionsoperationen und regelbasierte Verfeinerung umfasst. Dieser Beitrag beschreibt anhand eines kleinen Beispiels Petrinetz-Module. Zwei Petrinetzmodule beschreiben nach ihrer Komposition eine automatisierte Produktionszelle. Die beiden Module haben Sicherheitseigenschaft...

The intention of this paper is to extend the generic component framework presented at FASE 2002 to allow component verification based on export-import implications. In the generic component framework components with explicit import, export interfaces and a body specification connected by embeddings and transformations provide hierarchical compositi...

With the growing importance of model-driven development, the ability of transforming models into well-defined semantic domains becomes a key to automated analysis and verification in the software development process. In this paper we use the concept of typed attributed graph transformation to construct a model transformation from a simple version o...

Inthispaper,weproposeanew,loose semanticsfor place/tran- sition nets based on transition systems and generalizing the reachability graph semantics. The loose semantics of a place/transition net reflects all its possible refinements and is given as a category of transition systems with alternative sequences of events over the net. The main result st...

Changing environments - commercial, technical or social - demand software systems that can be adapted to those changes with reasonable effort. Component-based systems have been proposed as an adequate support for that task. Today there is no doubt on the importance of component-based systems. There are various specifications for the description of...

Abstract Software components are a useful and widely accepted abstraction mechanism,during the entire software life cycle from analysis to maintenance. They need to be backed by thorough formal concepts and modeling techniques, because the high complexity of component-based systems often impedes its consistency. The high complexity is caused mainly...

The intention of this paper is to extend our generic component framework presented at FASE 2002 (4) to a specific kind of connector architectures similar to architectural connections in the sense of Allen and Garlan (1). In our generic component framework we have considered compo- nents with explicit import, export and body parts connected by embed...

This paper introduces safety properties in the temporal logic sense (as defined in (Manna and Pnueli, 1995)) to Petri net modules. Petri net modules (Padberg, 2001, Padberg, 2002) have been achieved by a transfer of algebraic specification modules to Petri nets. They consist of three nets; the interface nets import and export, and the body of the m...

The relationship between graph grammars and Petri nets is the topic of this workshop with the emphasis on work in progress and especially the transfer of concepts between both areas. Both areas are prominent specification formalisms for concurrent and distributed systems. It is well-known that the token game of place-transition nets can be modeled...

Adhesive high-level replacement (HLR) categories and sys- tems are introduced as a new categorical framework for graph transfor- mation in a broad sense, which combines the well-known concept of HLR systems with the new concept of adhesive categories introduced by Lack and Soboci nski. In this paper we show that most of the HLR properties, which ha...

Adhesive high-level replacement (HLR) categories and sys-tems are introduced as a new categorical framework for graph transfor-mation in a broad sense, which combines the well-known concept of HLR systems with the new concept of adhesive categories introduced by Lack and Sobociski. In this paper we show that most of the HLR properties, which had be...

Specification techniques like Petri nets allow for the formal description and analysis of systems. Although tool support exists for many different Petri net classes and tasks, a domain-specific animation of net behavior, however, is not yet supported by many Petri net tools.

Case studies are frequently used as a means for testing new formalisms and modeling techniques in non-trivial environments. In this case study we use Petri net modules for structuring the operational behavior technique of nontrivial systems. We point out the advantages of our approach as well as possible starting points for further extension and im...

Message Sequence Charts (MSC) are well-known to be suitable to model scenarios in communication based systems. Scenarios using MSCs and Life Sequence Charts (LSC) have been presented already for the railway level crossing control systems (RLCCS) within the priority program of the German Research Council concerning Integration of Software Specificat...

Component-Based Software Engineering (CBSE) uses methods, tools and principles of general software engineering. However there is one distinction: CBSE distinguishes component development and system development with components.

This contribution gives the formal foundation for specification architectures. Specification architectures are given by diagrams in an arbitrary category of specifications. Hence this is in line with the extension form graph transformations to high-level replacement systems. We then transform diagrams in order to describe model evolution. We distin...

In the long history of Petri nets a universe of Petri nets has evolved consisting of an enormously rich theory, a wide variety of tools, and numerous successful applications and case studies in various application domains. This vast variety is not any more handable for anyone working with Petri nets, which results in the strong need of a structured...

This contribution provides a thorough survey of our work on rule-based refinement. Rule-based refinement comprises the transformation of Petri nets using rules while preserving certain system properties. Petri net rules and transformations are expressed by morphisms and pushouts. This allows an abstract formulation of our notions independent of a s...

The aim of this paper is a tutorial introduction to graph grammars and graph transformations on one hand and to Petri net transformations on the other hand. In addition to an introduction to both areas the paper shows how they have influenced each other. The concurrency concepts and semantics of graph transformations have been generalized from tho...

Here we present a new module concept for Petri nets that is based on the component concepts of Continuous Software Engineering (CSE). According to that concept two distinguished interfaces are required. These are import and export interfaces. The import describes the assumptions on the environment, e.g. in terms of used components. The export gives...

Here we present a new module concept for place/transition nets that is based on the component concepts of Continuous Software Engineering (CSE). Place/transition net modules consist of three nets, import, body and export. The import net IMP states the prerequisites the modules assumes. The body net BOD represents the internal functionality. The exp...

this paper are components of business processes in terms of net components and their composition in this approach. We use net components that are based on Petri nets. The nets are restricted FUNSOFT nets. These nets, called FEVA net are used to model business processes as well as their consistent composition

Automating software engineering activities for developing safety-critical systems reliably and correctly brings along the challenge to combine expressive specification methods with powerful analysis techniques. The focus of this paper lies in the analysis of graph transformation systems by analysis techniques transferred from Petri nets. Since Petr...

This contribution concerns transformations of specification architectures which are diagrams of sub-specifications. The graph of a diagram presents the architecture: nodes correspond to sub-specifications and edges to specification morphisms. We do not fix a specific visual specification technique, so this approach is in the tradition of high-level...

Starting from the algebraic view of Petri nets as monoids (as advocated by Meseguer and Montanari in [MM90]) we present the marking graphs of place transition nets as free monoid graphs and the marking graphs of speci c elementary nets as powerset graphs. These are two important special cases of a general categorical version of Petri nets based on...

The concept of parameterized net classes is introduced in order to allow a uniform approach to dierent kinds of Petri net classes.

The notion of processes for low-level Petri nets based on oc- currence nets is well known and it represents the basis for the study of the non-sequential behavior of Petri nets. Processes for high-level nets N are often defined as processes of the low level net Flat(N )w hich is obtained from N via a construction called "flattening". In this paper...

B. Braatz, H. Ehrig, K. Homann, J. Padberg, M. UrbasekTechnical University Berlin, GermanyInstitute for Software Technology and Theoretical Computer Sciencefbbraatz, ehrig, hoffmann, padberg, urbasekg@cs.tu-berlin.de1 Aims and

Here we present a new module concept for Petri nets that is based on the component concepts of Continuous Software Engineering (CSE). According to that concept two distinguished interfaces are required. These are import and export interfaces. The import describes the assumptions on the environment, e.g. in terms of used components. The export gives...

We present a new module concept for Petri nets that is based on the component concepts of Continuous Software Engineering (CSE). According to that concept two distinguished interfaces are required. These are import and export interfaces. The import describes the assumptions on the environment, e.g. in terms of used components. The export gives an a...

The concept of parameterized net classes is introduced in order to allow a uniform approach to different kinds of Petri net classes. By different actualizations of the net structure parameter and the data type formalism parameter we obtain several well-known net classes, like elementary nets, place-transition nets, colored nets, predicate transitio...

Contents: 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 Case Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Liveness Respecting Morphisms . . . . . . . . . . . . ....

The paper suggests a two-level approach to describe visually software architectures and their evolution. One visual modeling formalism is used to describe the architecture level while another is used to model the behavior of each component (component specification level). Graph transformation is applied for both levels to describe the modeling form...

This volume contains the contributions of the workshop Uniform Approaches to Graphical Process Specification Techniques (UNIGRA'01) held in Genova (31.3. – 1.4.2001) as a satellite of ETAPS 2001. The main idea of this workshop has been to bring together various unifying approaches from the areas of graph transformations, visual modeling techniques...

The concept of rule-based modification developed in the area of algebraic graph transformations and high-level replacement systems has recently shown to be a powerful concept for vertical structuring of Petri nets. This includes low- and high-level Petri nets, especially algebraic high-level nets which can be considered as an integration of algebra...