scispace - formally typeset

Book ChapterDOI

History-dependent Petri nets

25 Jun 2007-pp 164-183

TL;DR: It is shown that some classes of history-dependent nets can be automatically converted to classical Petri nets for analysis purposes and some classes are characterized by the form of the guards and sometimes the additional requirement that the underlying Classical Petri net is either bounded or has finite synchronization distances.

AbstractMost information systems that are driven by process models (e.g., workflow management systems) record events in event logs, also known as transaction logs or audit trails. We consider processes that not only keep track of their history in a log, but also make decisions based on this log. To model such processes we extend the basic Petri net framework with the notion of history and add guards to transitions evaluated on the process history. We show that some classes of history-dependent nets can be automatically converted to classical Petri nets for analysis purposes. These classes are characterized by the form of the guards (e.g., LTL guards) and sometimes the additional requirement that the underlying classical Petri net is either bounded or has finite synchronization distances.

Summary (3 min read)

1 Introduction

  • Numerous state-of-the-art enterprise information systems contain a workflow engine, which keeps track of all events as a part of its basic functionality.
  • To ensure safety, the authors require that b can fire only if the right traffic light is red, i.e., transitions d and e have fired the same number of times.
  • Global history is in fact a special case of token history for transparent systems where all components are aware of the actions of other components.
  • By introducing history-dependent guards, the authors increase the expressive power.
  • Since, the authors are interested not only in modeling but also in verification, they identify a number of important classes of global history nets (e.g. nets with LTL guards) that can be transformed to bisimilar classical Petri nets and provide corresponding transformations.

2 Preliminaries

  • The authors identify a bag with all elements occurring only once with the set containing the elements of the bag.
  • The authors overload the set notation, writing ∅ for the empty bag and ∈ for the element inclusion.
  • For sequences of elements over a set P the authors use the following notation:.
  • The authors will drop N and write R(m) when no ambiguity can arise.
  • A marked net (N, m0) is called bounded if its reachability set is finite.

3 Event History and History Logic

  • In this section the authors present the general notion of event history.
  • In the coming sections the authors investigate two kinds of nets that use event history: token history nets and global history nets.
  • Information on the relative order of events registered by different components might be missing.
  • Sets of formulae, terms and label expressions over Σ are denoted as FΣ, QΣ and LΣ, respectively.
  • One can show that for closed terms and formulae, i.e., terms and formulae where all variables appear in the scope of #, the result of the evaluation does not depend on ν.

4 Token History Nets

  • In this section the authors introduce token history nets as a special class of colored Petri nets [11] with history as color.
  • Recall that the union of two histories is defined for consistent histories only.
  • The following lemma states that consistency of markings is an invariant property (observe that a transition firing cannot destroy consistency).
  • To conclude this section the authors illustrate the semantics of token history nets.
  • The transition labeled d can fire consuming tokens [(p, H1)] and [(q, H3)] since the tokens share event e1 in their history.

5 Global History Nets

  • Where history is a separate object accessible when the guards of transitions are evaluated.the authors.
  • One can simulate inhibitor arcs by adding the condition m0(p) − #p + #p = 0. Since inhibitor nets are known to be Turing complete (cf. [17]), global history nets with unique labels are Turing complete as well.the authors.
  • Observe that in general it is impossible to derive the corresponding token histories from the history of a global history net.
  • It is easy to show that both nets are indeed bisimilar.

6 Global History Nets with Counting Formulae Guards

  • I.e., formulae that do not explore the precedence of events ≺.the authors.
  • Note that global history nets with counting formulae guards are Turing complete since they allow zero testing on the marking of a place.
  • To facilitate simulation and validation of these nets, the authors show that every global history net with counting formulae guards can be transformed into a bisimilar inhibitor net.
  • Furthermore, the authors identify conditions on the global history net implying that the net can be translated to a bisimilar classical Petri net.

6.1 Nets with Counting Formulae as Guards vs. Inhibitor Nets

  • For the sake of brevity the authors call these expressions basic counting formulae (over A and B).
  • The process terminates when all guards are true, i.e. the authors obtained a regular inhibitor net.
  • Figure 5 shows the basic idea of the eliminating a transition with guard g(t).
  • First the authors transform their net to a net where all guards are conjunctions of basic counting formulae by applying the following construction:.
  • The latter observation motivates their interest in the existence of a classical Petri net bisimilar to a global history net.

6.2 Guards Depending on the Marking Only

  • In this subsection the authors give conditions on the guards that allow a transformation into an equivalent bounded Petri net.
  • So global history nets satisfying these conditions will accept regular languages.
  • The authors consider here guards that depend only on the marking.

6.3 Counting Formulae with Bounded Synchronization Distance

  • The authors use here an important concept in Petri nets introduced by Carl Adam Petri: synchronization distance [4,7,13].
  • The authors use a generalization of this notion, the so-called y-distance [16].
  • If the authors take the underlying classical Petri net, the transitions are completely independent of each other and the y-distance is ∞ for any weight vector with at least one positive component.
  • (Idea) Disjunctions and conjunctions are taken care of as in Theorem 19.

7 Global History Nets with LTL Guards

  • Now the authors consider the class of global history nets with LTL guards.
  • While LTL formulae over infinite traces can be translated to Büchi automata, LTL formulae over finite traces can be translated to finite automata. [5] presents a translation algorithm that modifies standard LTL to Büchi automata conversion techniques to generate finite automata that accept finite traces satisfying LTL formulae.
  • The main aspect of modification there is the selection of accepting conditions.
  • Fig. 8 shows a simplistic example for a credit card company, where a credit card can be issued, reported lost, used for a payment or cancelled.
  • Note that this net can perform an arbitrary sequence of steps, and the place “true” has a token when the guard on the history should be evaluated to true and “false” when the guard should be evaluated to false.

9 Conclusion

  • In this paper the authors emphasize the importance of taking history into account while modelling processes.
  • Historical information is present in most state-of-the-art enterprise information systems.
  • The guard language will allow to evaluate conditions both on separate tokens and on their combinations.
  • The authors are going to develop a method for transforming broader subclasses of global history nets to classical and inhibitor Petri nets.
  • The authors are grateful to Jan Hidders and Jan Paredaens for a number of fruitful discussions at the early stages of this research.

Did you find this useful? Give us your feedback

...read more

Content maybe subject to copyright    Report

History-dependent Petri nets
Citation for published version (APA):
Van Hee, K., Serebrenik, A., Sidorova, N., & Van Aalst, W. D. (2007). History-dependent Petri nets. In A.
Yakovlev (Ed.),
Petri Nets and Other Models of Concurrency - ICATPN 2007 - 28th International Conference on
Applications and Theory of Petri Nets and Other Models of Concurrency, ICATPN 2007, Proceedings
(pp. 164-
183). (Lecture Notes in Computer Science; Vol. 4546). Springer. https://doi.org/10.1007/978-3-540-73094-1_12
DOI:
10.1007/978-3-540-73094-1_12
Document status and date:
Published: 01/12/2007
Document Version:
Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers)
Please check the document version of this publication:
• A submitted manuscript is the version of the article upon submission and before peer-review. There can be
important differences between the submitted version and the official published version of record. People
interested in the research are advised to contact the author for the final version of the publication, or visit the
DOI to the publisher's website.
• The final author version and the galley proof are versions of the publication after peer review.
• The final published version features the final layout of the paper including the volume, issue and page
numbers.
Link to publication
General rights
Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners
and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.
• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.
• You may not further distribute the material or use it for any profit-making activity or commercial gain
• You may freely distribute the URL identifying the publication in the public portal.
If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license above, please
follow below link for the End User Agreement:
www.tue.nl/taverne
Take down policy
If you believe that this document breaches copyright please contact us at:
openaccess@tue.nl
providing details and we will investigate your claim.
Download date: 09. Aug. 2022

History-Dependent Petri Nets
Kees van Hee, Alexander Serebrenik, Natalia Sidorova, and Wil van der Aalst
Department of Mathematics and Computer Science
Eindhoven University of Technology
P.O. Box 513, 5600 MB Eindhoven, The Netherlands
{k.m.v.hee,a.serebrenik,n.sidorova,w.m.p.v.d.aalst}@tue.nl
Abstract. Most information systems that are driven by process models
(e.g., workflow management systems) record events in event logs, also
known as transaction logs or audit trails. We consider processes that
not only keep track of their history in a log, but also make decisions
based on this log. To model such processes we extend the basic Petri
net framework with the notion of history and add guards to transitions
evaluated on the process history. We show that some classes of history-
dependent nets can be automatically converted to classical Petri nets
for analysis purposes. These classes are characterized by the form of
the guards (e.g., LTL guards) and sometimes the additional requirement
that the underlying classical Petri net is either bounded or has finite
synchronization distances.
1 Introduction
Numerous state-of-the-art enterprise information systems contain a workflow
engine, which keeps track of all events as a part of its basic functionality. In
this paper we consider processes that not only record the events but also make
choices based on the previous events, i.e. based on their history. The ability of
a system to change its behavior depending on its observed behavior is known
as adaptivity and in this sense this paper is about a special class of adaptive
systems.
In classical Petri nets the enabling of a transition depends only on the avail-
ability of tokens in the input places of the transition. We extend the model by
recording the history of the process and introducing transition guards evaluated
on the history. To illustrate the use of history, we consider a simple example of
two traffic lights on crossing roads.
Example 1. Figure 1 (left) presents two traffic lights, each modelled by a cycle
of three places and three transitions. The places model the states of each traffic
light (red, green and yellow), and the transitions change the lights from one color
to the next color. We assume that in the initial state both lights are red.
We want the system to be safe and fair, i.e., the traffic lights are never green
at the same time, the right traffic light can become green at most R times more
than the left traffic light, and similarly, the left traffic light can become green
at most L times more than the right traffic light. Usually one takes R =1and
J. Kleijn and A. Yakovlev (Eds.): ICATPN 2007, LNCS 4546, pp. 164–183, 2007.
c
Springer-Verlag Berlin Heidelberg 2007

History-Dependent Petri Nets 165
a
b
c f
d
e
RedL RedR
GreenL
YellowL
GreenR
YellowR
a
b
c f
d
e
RedL
RedR
GreenL
YellowL
GreenR
p
q
YellowR
Fig. 1. Traffic lights: without restrictions (left) and alternating (right)
a
b
c f
d
e
RedL RedR
GreenL
YellowL
GreenR
YellowR
p
q
a
b
c f
d
e
RedL
RedR
GreenL
YellowL
GreenR
YellowR
#{d}=#{e} and #{b}<#{e}+L
#{a}=#{b} and #{e}<#{b}+R
Fig. 2. A history-dependent Petri net with parameters R and L (left) and the history
guards replaced according to Theorem 23 for R =1andL =2(right)
L =0,orR =0andL = 1, implying alternating behavior of the traffic lights.
In order to obtain the alternating behavior one traditionally adds control places
p and q as in the right-hand side of Figure 1. This figure models the situation
with R =0andL = 1. Note that it is not easy to generalize this construction
for arbitrary R and L.
Our approach consists in making the guards explicit as shown in left-hand
side of Figure 2. To ensure safety, we require that b can fire only if the right
traffic light is red, i.e., transitions d and e have fired the same number of times.
The guard of b is written then as #{d} =#{e}. Similarly, e obtains the guard
#{a} =#{b}. In order to guarantee fairness, we require that in any history, b
fires at most L times more than e, i.e. #{b}≤#{e}+ L,ande fires at most R
times more than b, i.e., #{e}≤#{b}+ R. To ensure this we add the additional
requirement #{b} < #{e}+ L to the guard of b and the additional requirement
#{
e} < #{b}+ R to the guard of e. This results in the history-dependent Petri
net shown in Figure 2 (left).
Using history we can separate the modeling of the standard process informa-
tion (switching the traffic light to the following color) from additional require-
ments ensuring the desired behavior. Hence, we believe that introducing

166 K. van Hee et al.
history-dependent guards amounts to enhanced modeling comfort. Observe also
that global access to the history allows to ease modeling of synchronous choices.
Assume that at a certain point a choice has to be made between transitions a
and b. Assume further that the only impact of this choice is somewhere later in
the process: a
has to be chosen if a has been chosen and b
has to be chosen if b
has been chosen. A classical solution of this problem involves creating two places
p
a
and p
b
with the only incoming arc coming from a (b) and the only outgoing
arc leading to a
(b
). Rather than cluttering our model with additional places,
we set the guard of a
(b
)todemandthata (b) has been chosen before.
In this paper we consider two approaches to introduce history into the Petri
net model: (1) token history, where each individual token carries its own history,
i.e., history can be seen as special kind of color, and (2) global history,wherethere
is a single centralized history and every transition guard is evaluated on it (like
in our traffic lights example). Token history can be used in distributed settings
where different components do not have information about the actions of other
components. Global history is in fact a special case of token history for transparent
systems where all components are aware of the actions of other components.
By introducing history-dependent guards, we increase the expressive power.
On the traffic lights example, we can easily see that we can check the emptiness
of a place using history: RedR is empty if and only if #{e}−#{d} = 1. Hence,
we can model inhibitor arcs and consequently our formalism is Turing complete.
Since, we are interested not only in modeling but also in verification, we iden-
tify a number of important classes of global history nets (e.g. nets with LTL
guards) that can be transformed to bisimilar classical Petri nets and provide
corresponding transformations. For instance, the history-dependent net on the
left-hand side of Figure 2 can be automatically transformed to the classical net
on the right-hand side (we took R =1andL =2).
Due to the Turing completeness, not every history-dependent net can be repre-
sented by a classical Petri net. We are still interested in simulation and validation
of history-dependent nets. Simulation and validation are however complicated
by the fact that the representation of the current state of the system requires in
general an unbounded amount of memory, due to the growth of the history. We
solve this problem for a Turing complete subclass of global history nets (in which
we use event counting, but not event precedence in the guards) by defining a
transformation to bisimilar inhibitor nets. Inhibitor nets, though being Turing
complete, have a state representation of a fixed length (a marking), which makes
the simulation and validation feasible.
The remainder of the paper is organized as follows. After some preliminary
remarks in Section 2, we introduce the notion of event history together with a
history logic in Section 3. Section 4 introduces token history nets and Section 5
introduces global history nets. In Section 6 we show how to map several subclasses
of global history nets with counting formulae as guards to classical Petri nets
or inhibitor Petri nets, and in Section 7 we describe a transformation of global
history nets with LTL guards to classical Petri nets. Finally, we review the related
work and conclude the paper.

History-Dependent Petri Nets 167
2 Preliminaries
N denotes the set of natural numbers and Z the set of integers.
Let P be a set. A bag (multiset) m over P is a mapping m : P N.We
identify a bag with all elements occurring only once with the set containing the
elements of the bag. The set of all bags over P is denoted by N
P
.Weuse+
and for the sum and the difference of two bags and =,<,>, and for the
comparison of bags, which are defined in a standard way. We overload the set
notation, writing for the empty bag and for the element inclusion. We write
e.g. m =2[p]+[q] for a bag m with m(p)=2,m(q) = 1, and m(x) = 0 for all
x ∈{p, q}.Asusual,|m| and |S| stand for the number of elements in bag m and
in set S, respectively.
For (finite) sequences of elements over a set P we use the following notation:
The empty sequence is denoted with ; a non-empty sequence can be given by
listing its elements.
A transition system is a tuple E = S, Act ,T where S is a set of states, Act is
a finite set of action names and T S ×Act ×S is a transition relation.Wesay
that E is finite if S is finite. A process is a pair (E, s
0
)whereE is a transition
system and s
0
S an initial state. We denote (s
1
,a,s
2
) T as s
1
a
−→
E
s
2
,
and we say that a leads from s
1
to s
2
in E.WeomitE and write s
a
−→ s
whenever no ambiguity can arise. For a sequence of action names σ = a
1
...a
n
we write s
1
σ
−→ s
2
when s
1
= s
0
a
1
−→ s
1
a
2
−→ ...
a
n
−→ s
n
= s
2
.Next,s
1
−→ s
2
means that there exists a sequence σ T
such that s
1
σ
−→ s
2
.Wesaythats
2
is reachable from s
1
if and only if s
1
−→ s
2
. Finally, the language of a process
(E,s
0
), denoted L(E,s
0
), is defined as {σ | σ T
, s : s
0
σ
−→ s}.
Definition 2. Let E
1
= S
1
, Act,T
1
,E
2
= S
2
, Act,T
2
be transition systems.
ArelationR ⊆S
1
×S
2
is a simulation if and only if for all s
1
,s
1
∈S
1
, s
2
∈S
2
,
s
1
a
−→
E
1
s
1
implies that s
2
a
−→
E
2
s
2
and s
1
Rs
2
for some s
2
∈S
2
.
E
1
and E
2
are bisimilar if there exists a relation R ⊆S
1
×S
2
such that both
R and R
1
are simulations.
Next we introduce a number of notions related to Petri nets.
Definition 3. A Petri net N over a fixed set of labels Σ is a tuple P, T, F, Λ,
where: (1) P and T are two disjoint non-empty finite sets of places and tran-
sitions respectively; we call the elements of the set P T nodes of N ;(2)
F :(P × T ) (T × P ) N is a flow relation mapping pairs of places and
transitions to the naturals; (3) Λ : T Σ is a labeling function that maps
transitions of T to action labels from Σ.
An inhibitor net is a tuple P, T, F, Λ, I such that P, T, F, Λ is a Petri net
and I P × T is a set of inhibitor arcs.
We present nets with the usual graphical notation. For any pair of nodes x, y
with F (x, y) 1, we say that (x, y)isanarcwithweight F (x, y).

Citations
More filters

01 Jan 2010
TL;DR: A semantic model for scenarios that seamlessly integrates scenario-based specifications and state-based implementations is introduced, and a minimal set of notions to specify the behavior of distributed systems with scenarios are identified, called oclets.
Abstract: Scenario-based modeling has evolved as an accepted paradigm for developing complex systems of various kinds. Its main purpose is to ensure that a system provides desired behavior to its users. A scenario is generally understood as a behavioral requirement, denoting a course of actions that shall occur in the system. A typical notation of a scenario is a Message Sequence Chart or, more general, a finite partial order of actions. A specification is a set of scenarios. Intuitively, a system implements a specification if all scenarios of the specification can occur in the system. The main challenge in this approach is to systematically synthesize from a given scenario-based specification state-based components which together implement the specification; preferably to be achieved automatically. A further challenge is to analyze scenarios to avoid erroneous specifications. Existing scenario-based techniques exhibit a conceptual and formal gap between a scenariobased specification on the one hand and a state-based implementation on the other hand. This gap often renders synthesis surprisingly complex, and obscures the relationship between a specification and its implementation. Additionally, existing techniques for analyzing implementations cannot immediately be re-used for analyzing specifications, and vice versa. In this thesis, we introduce a semantic model for scenarios that seamlessly integrates scenario-based specifications and state-based implementations. We focus on modeling and analyzing the control-flow of systems. Technically, we use Petri nets together with the well established notion of distributed runs for (a) describing the semantics of scenarios, for (b) systematically constructing and analyzing a specification, and for (c) synthesizing an implementation from a given specification. Our first contribution is to identify a minimal set of notions to specify the behavior of distributed systems with scenarios. We formalize these notions in a novel semantic model for scenarios, called oclets. Oclets combine formal notions from Petri net theory with formal notions from scenario-based techniques in a unified way. We define a classical declarative semantics for scenario-based specifications which defines when a given set of runs satisfies a given specification. These semantics are compositional : a set of runs satisfies a composition of two specifications iff it satisfies each of the specifications. We then provide composition and decomposition operators on oclets and relations for comparing oclets. Using these notions, we systematically derive for each scenario-based specification S the behavior exhibited by a minimal implementation of S. The second contribution of this thesis aims at closing the conceptual and methodological gap between scenario-based specifications and state-based system models. In our approach, the semantics of scenarios and the semantics of systems both employ the same notions from Petri nets. We provide operational semantics for scenario-based specifications. On the basis of these operational semantics, we consider the problems of analyzing behavioral properties of specifications and of synthesizing components that implement the specification. We show that these problems are undecidable in general and we present a sufficient property for the decidable case. We then present algorithms for analysis and synthesis. We derive these results by generalizing existing techniques from Petri nets to the domain of scenario-based specifications. We implemented our algorithms for simulating, analyzing, and synthesizing from scenariobased specifications in our tool Greta. We report on an industrial case study that shows the feasibility of our techniques.

25 citations


Cites background from "History-dependent Petri nets"

  • ...[120] define history-dependent Petri nets in which each token records its history....

    [...]


Journal ArticleDOI
TL;DR: A weighted fuzzy reasoning algorithm is designed to address the reasoning problem of uncertain goal propositions and known goal concepts by combining forward reasoning with backward reasoning and therefore to facilitate cause analysis and handling of workflow exceptions.
Abstract: Exception handling plays a key role in dynamic workflow management that enables streamlined business processes. Handling application-specific exceptions is a knowledge-intensive process involving different decision-making strategies and a variety of knowledge, especially much fuzzy knowledge. Current efforts in workflow exception management are not adequate to support the knowledge-based exception handling. This paper proposes a hybrid exception handling approach based on two extended knowledge models, i.e., generalized fuzzy event-condition-action (GFECA) rule and typed fuzzy Petri net extended by process knowledge (TFPN-PK). The approach realizes integrated representation and reasoning of fuzzy and non-fuzzy knowledge as well as specific application domain knowledge and workflow process knowledge. In addition, it supports two handling strategies, i.e., direct decision and analysis-based decision, during exception management. The approach fills in the gaps in existing related researches, i.e., only providing the capability of direct exception handling and neglecting fuzzy knowledge. Based on TFPN-PK, a weighted fuzzy reasoning algorithm is designed to address the reasoning problem of uncertain goal propositions and known goal concepts by combining forward reasoning with backward reasoning and therefore to facilitate cause analysis and handling of workflow exceptions. A prototype system is developed to implement the proposed approach.

24 citations


Book ChapterDOI
24 Sep 2007
TL;DR: The adaptive workflow nets framework allows both healthcare providers and patients to get an insight into the past and current processes, but also foresee possible future developments, and ensures quality and timing of data communication essential for efficient information flow.
Abstract: Current challenges in Healthcare Information Systems (HIS) include supplying patients with personalized medical information, creating means for efficient information flow between different healthcare providers in order to lower risks of medical errors and increase the quality of care. To address these challenges, the information about patient-related processes, such as currently executed medical protocols, should be made available for medical staff and patients. Existing HIS are mostly data-centered, and therefore cannot provide an adequate solution. To give processes a prominent role in HIS, we apply the adaptive workflow nets framework. This framework allows both healthcare providers and patients to get an insight into the past and current processes, but also foresee possible future developments. It also ensures quality and timing of data communication essential for efficient information flow.

22 citations


Cites background or methods from "History-dependent Petri nets"

  • ...Global history nets [12] further extend Petri nets by assuming the availability of a history record, registering all firings and the time of firing together with the information which process performed it....

    [...]

  • ...Our approach relies on the framework of adaptive workflow nets [10,12]....

    [...]


01 Jan 2007
TL;DR: A new decision procedure is given for generalized soundness and a logic, called LogLogics, is introduced for the specification of guards based on a log of a current running process and an evaluation algorithm for such guards are given.
Abstract: In this thesis we focus on improving current modeling and verification techniques for complex business processes. The objective of the thesis is to consider several aspects of real-life business processes and give specific solutions to cope with their complexity. In particular, we address verification of a proper termination property for workflows, called generalized soundness. We give a new decision procedure for generalized soundness that improves the original decision procedure. The new decision procedure reports on the decidability status of generalized soundness and returns a counterexample in case the workflow net is not generalized sound. We report on experimental results obtained with the prototype implementation we made and describe how to verify large workflows compositionally, using reduction rules. Next, we concentrate on modeling and verification of adaptive workflows — workflows that are able to change their structure at runtime, for instance when some exceptional events occur. In order to model the exception handling properly and allow structural changes of the system in a modular way, we introduce a new class of nets, called adaptive workflow nets. Adaptive workflow nets are a special type of Nets in Nets and they allow for creation, deletion and transformation of net tokens at runtime and for two types of synchronizations: synchronization on proper termination and synchronization on exception. We define some behavioral properties of adaptive workflow nets: soundness and circumspectness and employ an abstraction to reduce the verification of these properties to the verification of behavioral properties of a finite state abstraction. Further, we study how formal methods can help in understanding and designing business processes. We investigate this for the extended event-driven process chains (eEPCs), a popular industrial business process language used in the ARIS Toolset. Several semantics have been proposed for EPCs. However, most of them concentrated solely on the control flow. We argue that other aspects of business processes must also be taken into account in order to analyze eEPCs and propose a semantics that takes data and time information from eEPCs into account. Moreover, we provide a translation of eEPCs to Timed Colored Petri nets in order to facilitate verification of eEPCs. Finally, we discuss modeling issues for business processes whose behavior may depend on the previous behavior of the process, history which is recorded by workflow management systems as a log. To increase the precision of models with respect to modeling choices depending on the process history, we introduce history-dependent guards. The obtained business processes are called historydependent processes.We introduce a logic, called LogLogics for the specification of guards based on a log of a current running process and give an evaluation algorithm for such guards. Moreover, we show how these guards can be used in practice and define LogLogics patterns for properties that occur most commonly in practice.

10 citations


Book ChapterDOI
24 Sep 2007
TL;DR: The problem of designing a careflow application as a form of process modelling, to be contrasted with older paradigms ranging from rule-based alerts and reminders to Petri nets and Critical path analysis is discussed.
Abstract: In this presentation we shall review different ways of describing the processes of delivering patient care, and relate these to traditional workflow in business processes, and the concept of "careflow" proposed by Panzarasa and her colleagues in Pavia. We shall discuss the problem of designing a careflow application as a form of process modelling, to be contrasted with older paradigms ranging from rule-based alerts and reminders to Petri nets and Critical path analysis. We shall also consider the need for specialised formalisms for describing clinical processes, drawing on experience with workflow languages (e.g. BPEL4WS, BPMN), guideline modelling languages (e.g. GLIF, PROforma), AI planning languages (e.g. PDDL, OCL) and "agent" programming systems (e.g. LALO, 3APL). The adoption of clinical workflow technology will greatly benefit from the availability of appropriate languages for declaratively representing processes of care. To explore some of the requirements for a clinical workflow technology we will review and critique the PROforma process modelling language and the Arezzo® and Tallis toolsets which use it. The discussion will be illustrated with deployed applications and operational prototypes.

6 citations


References
More filters

Book
01 Jan 1979
TL;DR: This book is a rigorous exposition of formal languages and models of computation, with an introduction to computational complexity, appropriate for upper-level computer science undergraduates who are comfortable with mathematical arguments.
Abstract: This book is a rigorous exposition of formal languages and models of computation, with an introduction to computational complexity. The authors present the theory in a concise and straightforward manner, with an eye out for the practical applications. Exercises at the end of each chapter, including some that have been solved, help readers confirm and enhance their understanding of the material. This book is appropriate for upper-level computer science undergraduates who are comfortable with mathematical arguments.

13,555 citations


"History-dependent Petri nets" refers background in this paper

  • ...Therefore, they can be made deterministic and minimized with standard algorithms [10]....

    [...]


Book
17 Oct 2011
Abstract: This is the third volume of a definitive work on coloured Petri nets. It contains a detailed presentation of 19 applications of CP-nets across a broad range of application areas, including a security system, ATM networks, audio/video systems, transaction processing, ISDN services, VLSI chips, document storage, distributed programming, electronic funds transfer, a naval vessel, chemical processing, nuclear waste management, and many more. Most of the projects were carried out in an industrial setting, and in each case the original authors have cooperated with the author and approved the new presentation. The author has taken care to unify the terminology and the CPN diagrams and to ensure that the background knowledge required has been provided in the first two volumes of the work.

2,040 citations


Kurt Jensen1
01 Jan 1995
TL;DR: This is the third volume of a definitive work on coloured Petri nets and contains a detailed presentation of 19 applications of CP-nets across a broad range of application areas, including a security system, ATM networks, audio/video systems, transaction processing, ISDN services, VLSI chips, document storage, distributed programming, electronic funds transfer, and many more.
Abstract: This is the third volume of a definitive work on coloured Petri nets. It contains a detailed presentation of 19 applications of CP-nets across a broad range of application areas, including a security system, ATM networks, audio/video systems, transaction processing, ISDN services, VLSI chips, document storage, distributed programming, electronic funds transfer, a naval vessel, chemical processing, nuclear waste management, and many more. Most of the projects were carried out in an industrial setting, and in each case the original authors have cooperated with the author and approved the new presentation. The author has taken care to unify the terminology and the CPN diagrams and to ensure that the background knowledge required has been provided in the first two volumes of the work.

1,688 citations


08 Sep 1986

669 citations


01 Jan 1990
Abstract: Publisher Summary This chapter presents an introduction to some of the basic issues in the study of program logics. The chapter describes various forms of first-order Dynamic Logic and discusses their syntax, semantics, proof theory, and expressiveness. The chapter discusses the power of auxiliary data structures such as arrays and stacks, and a powerful assignment statement called the nondeterministic assignment. Program logics differ from classical logics in that truth is dynamic rather than static. In classical predicate logic, the truth value of a formula is determined by a valuation of its free variables over some structure. The valuation and the truth value of the formula it induces are regarded as immutable. In program logics, there are explicit syntactic constructs called programs to change the values of variables, thereby changing the truth values of formulas. There are two main approaches to modal logics of programs: (1) the exogenous approach, exemplified by Dynamic Logic and its precursor, the Partial Correctness Assertions Method; and (2) the endogenous approach, exemplified by Temporal Logic and its precursor, the Inductive Assertions Method.

519 citations


Frequently Asked Questions (2)
Q1. What are the future works in "History-dependent petri nets" ?

The authors have provided means to model history-dependent processes by extending the classical Petri nets model and considered two ways of incorporating history: token history nets and global history nets. Future work. For the future work the authors plan to adapt their token net framework for modelling component-based systems. The authors intend to extend the language of operations on histories by adding projection in order to allow information hiding and intersection to check disjointness/presence of common parts in token histories. 

The authors consider processes that not only keep track of their history in a log, but also make decisions based on this log. The authors show that some classes of historydependent nets can be automatically converted to classical Petri nets for analysis purposes.