Reconfigurable Decorated PT Nets with Inhibitor Arcs and Transition Priorities

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 transition may fire only if it has the highest priority of all enabled transitions. This concept is shown to be compatible with reconfigurable Petri nets

Subtyping for Hierarchical, Reconfigurable Petri Nets

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 subnets. These subnets are themselves reconfigurable, so they are supplied with their own set of rules. Moreover, global rules that can be applied in all of the net, are provided

Permutation Equivalence of DPO Derivations with Negative Application Conditions based on Subobject Transformation Systems: Long Version

Switch equivalence for transformation systems has been successfully used in many domains for the analysis of concurrent behaviour. When using graph transformation as modelling framework for these systems the concept of negative application conditions (NACs) is widely used -- in particular for the specification of operational semantics. In this paper we show that switch equivalence can be improved essentially for the analysis of systems with NACs by our new concept of permutation equivalence. Two derivations respecting all NACs are called permutation-equivalent if they are switch-equivalent disregarding the NACs. In fact, there are permutation-equivalent derivations which are not switch-equivalent with NACs. As main result of the paper, we solve the following problem: Given a derivation with NACs, we can efficiently derive all permutation-equivalent derivations to the given one by static analysis. The results are based on extended techniques for subobject transformation systems which have been introduced recently

RONs Revisited: General Approach to Model Reconfigurable Object Nets based on Algebraic High-Level Nets

Reconfigurable Object Nets (RONs) have been implemented in our group to support the visual specification of controlled rule-based transformations of marked place/transition (P/T) nets. RONs are high-level nets (system nets) with two types of tokens: object nets (P/T nets) and net transformation rules. System net transitions can be of different types to fire object net transitions, move object nets through the system net, or to apply a net transformation rule to an object net. The disadvantage of the RON approach and tool is the limitation of object nets to P/T nets and the limitation of the underlying semantics of RONs due to the fixed types for system net transitions. Often, a more general approach is preferred where the type of object nets and the behavior of reconfigurations may be defined in a more flexible way. In this paper, we propose to use Algebraic High-Level nets with individual tokens (AHLI nets) as system nets. In this more general approach, tokens may be any type of Petri nets, defined by the corresponding algebraic signature and algebra. To support this general approach, a development environment for AHLI nets is currently implemented which allows the user to edit and simulate AHLI nets. We present the formalization of RONs as special AHLI nets and describe the current state of the AHLI net tool environment

Process Construction and Analysis for Workflows Modelled by Adhesive HLR Systems with Application Conditions

Graph transformation systems (gts) are suitable for modelling concurrent and distributed behaviour of systems and in particular of workflows. Analysis of the behaviour of these models is in general highly complex but it is of main interest, especially for optimizing the system execution. Main focus of the PhD project is a formal approach for constructing the process of a workflow scenario to support possibilities of efficient analysis and execution. Based on the abstract framework of adhesive high level replacement systems the developed techniques will be applied on two levels. First, the framework is instantiated to different kinds of graph as well as Petri net transformation systems which are key ingredient for modelling mobile networks in [1]. In the second level, the modelling techniques are used to specify the production of industrial products, which can involve several thousands of production steps. A case study will show how a chain of production steps taken from a real production facility can be modelled as gts derivation. Formal techniques for process construction and analysis known for basic cases only have to be extended in various dimensions in order to be applied to the model and in general to the domain of workflows. A practical evaluation will compare the results with those derived by standard techniques for process analysis

Foundations of Software Science and Computation Structures

This open access book constitutes the proceedings of the 22nd International Conference on Foundations of Software Science and Computational Structures, FOSSACS 2019, which took place in Prague, Czech Republic, in April 2019, held as part of the European Joint Conference on Theory and Practice of Software, ETAPS 2019. The 29 papers presented in this volume were carefully reviewed and selected from 85 submissions. They deal with foundational research with a clear significance for software science