A recursive paradigm for aligning observed behavior of large structured process models

The alignment of observed and modeled behavior is a crucial problem in process mining, since it opens the door for conformance checking and enhancement of process models. The state of the art techniques for the computation of alignments rely on a full exploration of the combination of the model state space and the observed behavior (an event log), which hampers their applicability for large instances. This paper presents a fresh view to the alignment problem: the computation of alignments is casted as the resolution of Integer Linear Programming models, where the user can decide the granularity of the alignment steps. Moreover, a novel recursive strategy is used to split the problem into small pieces, exponentially reducing the complexity of the ILP models to be solved. The contributions of this paper represent a promising alternative to fight the inherent complexity of computing alignments for large instances.Peer ReviewedPostprint (author's final draft

A symbolic algorithm for the synthesis of bounded Petri nets

This paper presents an algorithm for the synthesis of bounded Petri nets from transition systems. A bounded Petri net is always provided in case it exists. Otherwise, the events are split into several transitions to guarantee the synthesis of a Petri net with bisimilar behavior. The algorithm uses symbolic representations of multisets of states to efficiently generate all the minimal regions. The algorithm has been implemented in a tool. Experimental results show a significant net reduction when compared with approaches for the synthesis of safe Petri nets.Peer ReviewedPostprint (author's final draft

A Model Driven Approach to the Analysis of Timeliness Properties

Abstract. The need for a design language that is rigorous but accessible and intuitive is often at odds with the formal and mathematical nature of languages used for analysis. UML and Petri Nets are a good example of this dichotomy. UML is a widely accepted modelling language capable of modelling the structural and behavioural aspects of a system. However UML lacks the mathematical foundation that is required for rigorous analysis. Petri Nets on the other hand have a strong mathematical base that is well suited for analysis of a system but lacks the appeal and ease-of-use of UML. Design in UML languages such as Sequence Diagrams and analysis in Petri Nets require on one hand some expertise in potentially two incompatible systems and their tools, and on the other a seamless transition from one system to the other. One way of addressing this impediment is to focus the software development mainly on the design language system and to facilitate the transition to the formal analysis by means of a combination of automation and tool support. The aim of this paper is to present a transformation system, which takes UML Sequence Diagrams augmented with time constraints and generates semantically equivalent Petri Nets that preserve the timing requirements. A case study on a small network is used in order to illustrate the proposed approach and in particular the design, the transformation and the analysis processes.

Reactive Petri Nets for Workflow Modeling

Petri nets are widely used for modeling and analyzing workflows

The triconnected abstraction of process models

Companies use business process models to represent their working procedures in order to deploy services to markets, to analyze them, and to improve upon them. Competitive markets necessitate complex procedures, which lead to large process specifications with sophisticated structures. Real world process models can often incorporate hundreds of modeling constructs. While a large degree of detail complicates the comprehension of the processes, it is essential to many analysis tasks. This paper presents a technique to abstract, i.e., to simplify process models. Given a detailed model, we introduce abstraction rules which generalize process fragments in order to bring the model to a higher abstraction level. The approach is suited for the abstraction of large process specifications in order to aid model comprehension as well as decomposing problems of process model analysis. The work is based on process structure trees that have recently been introduced to the field of business process management

Comparing Petri Net and Activity Diagram Variants for Workflow Modelling:A Quest for Reactive Petri Nets

Petri net variants are widely used as a workflow modelling technique. Recently, UMLa ctivity diagrams have been used for the same purpose, even though the syntax and semantics of activity diagrams has not been yet fully worked out. Nevertheless, activity diagrams seem very similar to Petri nets and on the surface, one may think that they are variants of each other. To substantiate or deny this claim, we need to formalise the intended semantics of activity diagrams and then compare this with various Petri net semantics. In previous papers we have defined two formal semantics for UMLact ivity diagrams that are intended for workflow modelling. In this paper, we discuss the design choices that underlie these two semantics and investigate whether these design choices can be met in low-level and high-level Petri net semantics. We argue that the main difference between the Petri net semantics and our semantics of UML act ivity diagrams is that the Petri net semantics models resource usage of closed, active systems that are non-reactive, whereas our semantics of UMLact ivity diagrams models open, reactive systems. Since workflow systems are open, reactive systems, we conclude that Petri nets cannot model workflows accurately, unless they are extended with a syntax and semantics for reactivity

Formal analysis of executions of organizational scenarios based on process-oriented specifications

Abstract This paper presents various formal techniques for analysis of executions of organizational scenarios based on specifications of organizations. Organizational specifications describe (prescribe) ordering and timing relations on organizational processes, modes of use of resources, allocations of actors to processes, etc. The actual execution may diverge from scenarios (pre)defined by a specification. A part of techniques proposed in this paper is dedicated to establishing the correspondence between a formalized execution (i.e., a trace) and the corresponding specification. Other techniques proposed in this paper provide the analyst with wide possibilities to evaluate organizational performance and to identify bottlenecks and other inefficiencies in the organizational operation. For the proposed formal analysis the order-sorted predicate Temporal Trace Language (TTL) is used and it is supported by the dedicated software tool TTL Checker. The analysis approaches considered in this paper are illustrated by a case study in the context of an organization from the security domain. © Springer Science+Business Media, LLC 2009

Verification of Logs - Revealing Faulty Processes of a Medical Laboratory

Abstract. If there is a suspicion of Lyme disease, a blood sample of a patient is sent to a medical laboratory. The laboratory performs a number of dierent blood examinations testing for antibodies against the Lyme disease bacteria. The total number of dierent examinations depends on the intermediate results of the blood count. The costs of each examination is paid by the health insurance company of the patient. To control and restrict the number of performed examinations the health insurance companies provide a charges regulation document. If a health insurance company disagrees with the charges of a laboratory it is the job of the public prosecution service to validate the charges according to the regulation document. In this paper we present a case study showing a systematic approach to reveal faulty processes of a medical laboratory. First, files produced by the information system of the respective laboratory are analysed and consolidated in a database. An excerpt from this database is translated into an event log describing a sequential language of events performed by the information system. With the help of the regulation document this language can be split in two sets- the set of valid and the set of faulty words. In a next step, we build a coloured Petri net model corre-sponding to the set of valid words in a sense that only the valid words are executable in the Petri net model. In a last step we translated the coloured Petri net into a PL/SQL-program. This program can automat-ically reveal all faulty processes stored in the database.