Soundness of workflow nets: classification, decidability, and analysis

Workflow nets, a particular class of Petri nets, have become one of the standard ways to model and analyze workflows. Typically, they are used as an abstraction of the workflow that is used to check the so-called soundness property. This property guarantees the absence of livelocks, deadlocks, and other anomalies that can be detected without domain knowledge. Several authors have proposed alternative notions of soundness and have suggested to use more expressive languages, e.g., models with cancellations or priorities. This paper provides an overview of the different notions of soundness and investigates these in the presence of different extensions of workflow nets.We will show that the eight soundness notions described in the literature are decidable for workflow nets. However, most extensions will make all of these notions undecidable. These new results show the theoretical limits of workflow verification. Moreover, we discuss some of the analysis approaches described in the literature.

Untanglings: A novel approach to analyzing concurrent systems

Substantial research efforts have been expended to deal with the complexity of concurrent systems that is inherent to their analysis, e.g., works that tackle the well-known state space explosion problem. Approaches differ in the classes of properties that they are able to suitably check and this is largely a result of the way they balance the trade-off between analysis time and space employed to describe a concurrent system. One interesting class of properties is concerned with behavioral characteristics. These properties are conveniently expressed in terms of computations, or runs, in concurrent systems. This article introduces the theory of untanglings that exploits a particular representation of a collection of runs in a concurrent system. It is shown that a representative untangling of a bounded concurrent system can be constructed that captures all and only the behavior of the system. Representative untanglings strike a unique balance between time and space, yet provide a single model for the convenient extraction of various behavioral properties. Performance measurements in terms of construction time and size of representative untanglings with respect to the original specifications of concurrent systems, conducted on a collection of models from practice, confirm the scalability of the approach. Finally, this article demonstrates practical benefits of using representative untanglings when checking various behavioral properties of concurrent systems.

On the expressive power of behavioral profiles

Behavioral profiles have been proposed as a behavioral abstraction of dynamic systems, specifically in the context of business process modeling. A behavioral profile can be seen as a complete graph over a set of task labels, where each edge is annotated with one relation from a given set of binary behavioral relations. Since their introduction, behavioral profiles were argued to provide a convenient way for comparing pairs of process models with respect to their behavior or computing behavioral similarity between process models. Still, as of today, there is little understanding of the expressive power of behavioral profiles. Via counter-examples, several authors have shown that behavioral profiles over various sets of behavioral relations cannot distinguish certain systems up to trace equivalence, even for restricted classes of systems represented as safe workflow nets. This paper studies the expressive power of behavioral profiles from two angles. Firstly, the paper investigates the expressive power of behavioral profiles and systems captured as acyclic workflow nets. It is shown that for unlabeled acyclic workflow net systems, behavioral profiles over a simple set of behavioral relations are expressive up to configuration equivalence. When systems are labeled, this result does not hold for any of several previously proposed sets of behavioral relations. Secondly, the paper compares the expressive power of behavioral profiles and regular languages. It is shown that for any set of behavioral relations, behavioral profiles are strictly less expressive than regular languages, entailing that behavioral profiles cannot be used to decide trace equivalence of finite automata and thus Petri nets.

What parents value from formal support services in the context of identified child abuse

Parents whose children are identified as having experienced or being at risk of experiencing significant harm potentially provide an invaluable dimension to our understanding of the circumstances that result in child abuse or neglect and how best to respond to these invariably complex situations. This paper reports findings from a study of the experiences of six parents. In-depth interviews were conducted with four mothers and two fathers who had been referred to an intensive family support services by the Queensland statutory child protection authority. Using a critical ecological perspective, the study focused on identifying and understanding the experiences of the parents in using formal family support services, including aspects of service delivery that were helpful or unhelpful. Parents also commented on their experiences of statutory child protection services. Service components and worker qualities that parents identified as being helpful included being accessible, targeted and integrated and being able to meet a continuum of needs, from a micro to a broader level. Their reports provide invaluable insight into how formal family support services, including child protection services, can better meet the needs of parents in addressing the recurring problem of child maltreatment.

Normative requirements for regulatory compliance: An abstract formal framework

By definition, regulatory rules (in legal context called norms) intend to achieve specific behaviour from business processes, and might be relevant to the whole or part of a business process. They can impose conditions on different aspects of process models, e.g., control-flow, data and resources etc. Based on the rules sets, norms can be classified into various classes and sub-classes according to their effects. This paper presents an abstract framework consisting of a list of norms and a generic compliance checking approach on the idea of (possible) execution of processes. The proposed framework is independent of any existing formalism, and provides a conceptually rich and exhaustive ontology and semantics of norms needed for business process compliance checking. The possible uses of the proposed framework include to compare different compliance management frameworks (CMFs).

Emotional aspects

Through adolescence, young people are at an exciting point of their maturation. On the whole they are thoughtful, caring and responsible people. In many ways they are just beginning to make valuable contributions to the society they will soon be steering. They are critical and reflective, and they are passionate and energetic. We have discovered in earlier chapters the types of physical and cognitive changes and developments that confront adolescents. In this chapter we will explore emotional and moral development and allied issues of resilience and vulnerability. The emotional dimension of adolescence can tie in with several other issues that extend from aloneness, loneliness and alienation. We will introduce key theory and theorists in the field of emotional and moral development (such as Kohlberg). Some adolescents have a traumatic time (as do people of all ages and phases of life) and this book wouldn’t be whole without a brief discussion of the types of issues that emerge as young people in the throes of developing their moral and emotional perspective of the world are dealt life challenges.