1,982 research outputs found
Learning Hybrid Process Models From Events: Process Discovery Without Faking Confidence
Process discovery techniques return process models that are either formal
(precisely describing the possible behaviors) or informal (merely a "picture"
not allowing for any form of formal reasoning). Formal models are able to
classify traces (i.e., sequences of events) as fitting or non-fitting. Most
process mining approaches described in the literature produce such models. This
is in stark contrast with the over 25 available commercial process mining tools
that only discover informal process models that remain deliberately vague on
the precise set of possible traces. There are two main reasons why vendors
resort to such models: scalability and simplicity. In this paper, we propose to
combine the best of both worlds: discovering hybrid process models that have
formal and informal elements. As a proof of concept we present a discovery
technique based on hybrid Petri nets. These models allow for formal reasoning,
but also reveal information that cannot be captured in mainstream formal
models. A novel discovery algorithm returning hybrid Petri nets has been
implemented in ProM and has been applied to several real-life event logs. The
results clearly demonstrate the advantages of remaining "vague" when there is
not enough "evidence" in the data or standard modeling constructs do not "fit".
Moreover, the approach is scalable enough to be incorporated in
industrial-strength process mining tools.Comment: 25 pages, 12 figure
Adding Priority to Event Structures
Event Structures (ESs) are mainly concerned with the representation of causal
relationships between events, usually accompanied by other event relations
capturing conflicts and disabling. Among the most prominent variants of ESs are
Prime ESs, Bundle ESs, Stable ESs, and Dual ESs, which differ in their
causality models and event relations. Yet, some application domains require
further kinds of relations between events. Here, we add the possibility to
express priority relationships among events.
We exemplify our approach on Prime, Bundle, Extended Bundle, and Dual ESs.
Technically, we enhance these variants in the same way. For each variant, we
then study the interference between priority and the other event relations.
From this, we extract the redundant priority pairs-notably differing for the
types of ESs-that enable us to provide a comparison between the extensions. We
also exhibit that priority considerably complicates the definition of partial
orders in ESs.Comment: In Proceedings EXPRESS/SOS 2013, arXiv:1307.690
Petri nets for systems and synthetic biology
We give a description of a Petri net-based framework for
modelling and analysing biochemical pathways, which uni¯es the qualita-
tive, stochastic and continuous paradigms. Each perspective adds its con-
tribution to the understanding of the system, thus the three approaches
do not compete, but complement each other. We illustrate our approach
by applying it to an extended model of the three stage cascade, which
forms the core of the ERK signal transduction pathway. Consequently
our focus is on transient behaviour analysis. We demonstrate how quali-
tative descriptions are abstractions over stochastic or continuous descrip-
tions, and show that the stochastic and continuous models approximate
each other. Although our framework is based on Petri nets, it can be
applied more widely to other formalisms which are used to model and
analyse biochemical networks
Formal Relationships Between Geometrical and Classical Models for Concurrency
A wide variety of models for concurrent programs has been proposed during the
past decades, each one focusing on various aspects of computations: trace
equivalence, causality between events, conflicts and schedules due to resource
accesses, etc. More recently, models with a geometrical flavor have been
introduced, based on the notion of cubical set. These models are very rich and
expressive since they can represent commutation between any bunch of events,
thus generalizing the principle of true concurrency. While they seem to be very
promising - because they make possible the use of techniques from algebraic
topology in order to study concurrent computations - they have not yet been
precisely related to the previous models, and the purpose of this paper is to
fill this gap. In particular, we describe an adjunction between Petri nets and
cubical sets which extends the previously known adjunction between Petri nets
and asynchronous transition systems by Nielsen and Winskel
Independence and concurrent separation logic
A compositional Petri net-based semantics is given to a simple language
allowing pointer manipulation and parallelism. The model is then applied to
give a notion of validity to the judgements made by concurrent separation logic
that emphasizes the process-environment duality inherent in such rely-guarantee
reasoning. Soundness of the rules of concurrent separation logic with respect
to this definition of validity is shown. The independence information retained
by the Petri net model is then exploited to characterize the independence of
parallel processes enforced by the logic. This is shown to permit a refinement
operation capable of changing the granularity of atomic actions
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