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1
Content available remote Automated Repair of Process Models with Non-local Constraints Using State-Based Region Theory
Kalenkova Anna, Polyvyanyy Artem, Carmona Josep, La Rosa Marcello
Fundamenta Informaticae
|
2021
|
Vol. 183, nr 3-4
293--317
EN
State-of-the-art process discovery methods construct free-choice process models from event logs. Consequently, the constructed models do not take into account indirect dependencies between events. Whenever the input behaviour is not free-choice, these methods fail to provide a precise model. In this paper, we propose a novel approach for enhancing free-choice process models by adding non-free-choice constructs discovered a-posteriori via region-based techniques. This allows us to benefit from the performance of existing process discovery methods and the accuracy of the employed fundamental synthesis techniques. We prove that the proposed approach preserves fitness with respect to the event log while improving the precision when indirect dependencies exist. The approach has been implemented and tested on both synthetic and real-life datasets. The results show its effectiveness in repairing models discovered from event logs.
2
Content available remote Multiplicative Transition Systems
Winkowski J.
Fundamenta Informaticae
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2011
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Vol. 109, nr 2
201-222
EN
The paper is concerned with algebras whose elements can be used to represent runs of a system from a state to a state. These algebras, called multiplicative transition systems, are categories with respect to a partial binary operation called composition. They can be characterized by axioms such that their elements and operations can be represented by partially ordered multisets of a certain type and operations on such multisets. The representation can be obtained without assuming a discrete nature of represented elements. In particular, it remains valid for systems with infinitely divisible elements, and thus also for systems with elements which can represent continuous and partially continuous runs.
3
Content available remote Multiplicative Transition Systems
Winkowski J.
Prace Instytutu Podstaw Informatyki Polskiej Akademii Nauk
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2010
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Nr 1018
1-29
EN
The paper is concerned with algebras whose elements can be used to represent runs of a system from a state to a state. These algebras, called multiplicative transition systems, are categories with respect to a partial binary operation called composition. They can be characterized by axioms such that their elements and operations can be represented by partially ordered multisets of a certain type and operations on such multisets. The representation can be obtained without assuming a discrete nature of represented elements. In particular, it remains valid for systems with innitely divisible elements, and thus also for systems with elements which can represent continuous and partially continuous runs.
PL
Praca dotyczy algebr, których elementy mogą być użyte do reprezentowania przebiegów dowolnego systemu od stanu do stanu. Te algebry, zwane multyplikatywnymi systemami tranzycyjnymi, są kategoriami ze względu na częściową operację binarną zwaną składaniem. Można je scharakteryzować aksjomatami tak, że ich elementy i operację składania można reprezentować częściowo uporządkowanymi wielozbiorami pewnego typu i operacją składania takich wielozbiorów. Taką reprezentację można otrzymać bez zakładania dyskretności reprezentowanych elementów. W szczególności jest ona możliwa dla systemów o nieskończenie podzielnych elementach, a więc i dla systemów których elementy mogą reprezentować przebiegi ciągłe i częściowo ciągłe.
4
Content available remote Minimal Regions of ENL-Transition Systems
Koutny M., Pietkiewicz-Koutny M.
Fundamenta Informaticae
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2010
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Vol. 101, nr 1/2
45-58
EN
One of the possible ways of constructing concurrent systems is their automated synthesis from behavioural specifications. In this paper, we look at a particular instance of this approach which aims at constructing GALS (globally asynchronous locally synchronous) systems from specifications given in terms of transition systems with arcs labelled by steps of executed actions. GALS systems are represented by Elementary Net Systems with Localities (ENL-systems), each locality defining a set of co-located actions. The synthesis procedure is based on the regions of transition systems and we provide a number of criteria aimed at generating a minimal set of regions (conditions) of an ENL-system generating a given transition system.
5
Content available remote Synthesis of Elementary Net Systems with Context Arcs and Localities
Koutny M., Pietkiewicz-Koutny M.
Fundamenta Informaticae
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2008
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Vol. 88, nr 3
307-328
EN
We investigate the synthesis problem for ENCL-systems, defined as Elementary Net Systems extended with context (inhibitor and activator) arcs and explicit event localities. Since colocated events are meant to be executed synchronously, the behaviour of such systems is captured by step transition systems, where arcs are labelled by sets of events rather than by single events. We completely characterise transition systems generated by ENCL-systems after extending the standard notion of a region - defined as a certain set of states - with explicit information about events which, in particular, are responsible for crossing its border. As a result, we are able to construct, for each such transition system, a suitable ENCL-system generating it.
6
Content available remote Stochastic Petri Box Calculus with Discrete Time
Tarasyuk I.V.
Fundamenta Informaticae
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2007
|
Vol. 76, nr 1-2
189-218
EN
In the last decades, a number of stochastic enrichments of process algebras was constructed to allow one for specification of stochastic processes within the well-developed framework of algebraic calculi. In [], a continuous time stochastic extension of finite Petri box calculus (PBC) was proposed called sPBC. The algebra sPBC has interleaving semantics due to the properties of continuous time distributions. At the same time, PBC has step semantics, and it could be natural to propose its concurrent stochastic enrichment. We construct a discrete time stochastic extension dtsPBC of finite PBC. A step operational semantics is defined in terms of labeled transition systems based on action and inaction rules. A denotational semantics is defined in terms of a subclass of labeled discrete time stochastic Petri nets (LDTSPNs) called discrete time stochastic Petri boxes (dts-boxes). A consistency of both semantics is demonstrated. In addition, we define a variety of probabilistic equivalences that allow one to identify stochastic processes with similar behaviour which are differentiated by too strict notion of the semantic equivalence. The interrelations of all the introduced equivalences are investigated.
7
Content available remote Agents that Know How to Play
Jamroga W., Van der Hoek W.
Fundamenta Informaticae
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2004
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Vol. 63, nr 2,3
185--219
EN
We look at ways to enrich Alternating-time Temporal Logic (ATL) - a logic for specification and verification of multi-agent systems - with a notion of knowledge. Starting point of our study is a recent proposal for a system called Alternating-time Temporal Epistemic Logic (ATEL). We show that, assuming that agents act under uncertainty in some states of the system, the notion of allowable strategy should be defined with some caution. Moreover, we demonstrate a subtle difference between an agent knowing that he has a suitable strategy and knowing the strategy itself. We also point out that the agents should be assumed similar epistemic capabilities in the semantics of both strategic and epistemic operators. Trying to implement these ideas, we propose two different modifications of ATEL. The first one, dubbed Alternating-time Temporal Observational Logic (ATOL), is a logic for agents with bounded recall of the past. With the second, ATEL-R*, we present a framework to reason about both perfect and imperfect recall, in which we also incorporate operators for reasoning about the past. We identify some feasible subsystems of this expressive system.
8
Content available remote Transition systems without transitions
Borzyszkowski A. M., Darondeau P.
Prace Instytutu Podstaw Informatyki Polskiej Akademii Nauk
|
2003
|
Nr 964
1-7
EN
We study the problem of embedding partial 2-structures into set 2-structures such that the target substructure is full and forward closed and it is minimal w.r.t. these properties.
PL
Badamy problem takiego zanurzenia częściowej 2-struktury w 2-strukturę zbiorową, by docelowa 2-struktura była pełna, domknięta w przód i minimalna względem tych własności.
9
Content available remote Synthesising Elementary Net Systems with Inhibitor Ares from Step Transition Systems
Pietkiewicz-Koutny M.
Fundamenta Informaticae
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2002
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Vol. 50, nr 2
175-203
EN
We here consider transition systems of Elementary Net Systems with Inhibitor Arcs. There are basically two different types of non-interleaving semantics of such Petri nets, the a-posteriori and a-priori semantics. The synthesis problem for Elementary Net Systems with Inhibitor Arcs executed under the a-priori semantics (ENI) was solved in [18]. In this paper we completely characterise transition systems which can be generated by Elementary Net Systems with Inhibitor Arcs executed under the a-posteriori semantics (ENIapost). This is achieved by adapting the notion of a step transition system, i.e. one in which arcs are labelled by sets of events executed concurrently. In developing the model, we follow the standard approach in which the relationship between nets and their transition systems is established via the notion of a region. We define, and show consistency of, two behaviour preserving translations between nets and transition systems. We then compare transition systems which are generated by ENIapost and ENI-systems (called respectively TSENIapost and TSENI transition systems).
10
Transition probabilities and transition systems
Frej B.
Prace Naukowe Instytutu Matematyki Politechniki Wrocławskiej. Konferencje
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2001
|
Vol. 24, nr 3
44-53
EN
The paper contains an example of three commuting transition probabilities T, S, U inducing continuous transition system and such that the iterates Tk, Sk, Uk admit no trajectories for any natural k.
11
Content available remote General morphisms of Petri nets
Bednarczyk M., Borzyszkowski A.
Prace Instytutu Podstaw Informatyki Polskiej Akademii Nauk
|
1999
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nr 874
3-24
EN
A new notion of a general morphism of Petri nets is introduced. The new morphisms are shown to properly include the morphisms considered so far. The resulting category of general Petri nets is shown to admit products. Here, it is shown that the new notion turns out to be indispensable to facilitate functoriality of synthesis of transition systems by means of (labelled) state machines. In the companion paper this result is used to synthesize concrete asynchronous systems studied by Morin as a mixed products of state machines.
PL
W pracy zaproponowano nowe, uogolnione pojęcie morfizmu dla sieci Petriego. Pokazano, że klasa tych morfizmów jest istotnie bogatsza od dotychczas rozważanych klas morfizmów. Otrzymana w ten sposób kategoria sieci Petriego posiada produkty. W niniejszej pracy pokazano, iż uogólnione morfizmy są niezbędne do zapewnienia funktorialności procesu syntezy tranzycji za pomocą (etykietowanych) maszyn stanowych. W innej pracy autorów pokazano, iz rezultat ten można zastosować w procesie syntezy konkretnych systemów asynchronicznych badanych przez Morin'a poprzez produkty mieszane maszyn stanowych.
12
Content available remote Concurrent realizations of reactive systems
Bednarczyk M., Borzyszkowski A.
Prace Instytutu Podstaw Informatyki Polskiej Akademii Nauk
|
1999
|
nr 881
3-23
PL
Omawiany jest problem znajdowania (funktorialnej) współbieżnej realizacji systemu reaktywnego jako etykietowanej bezpiecznej sieci Petriego. Najpierw opisana jest funktorialna konstrukcja prowadząca z kategorii konkretnych systemów asynchronicznych, wprowadzonych przez Morina, do kategorii etykietowanych bezpiecznych sieci Petriego. Następnie omówiony jest problem w pełnej ogólności. Na ogół nie istnieje optymalne rozwiązanie, tzn. nie istnieje najbardziej współbieżna realizacja systemu reaktywnego. Niemniej wskazana jest droga budowania pewnej współbieżnej realizacji systemu reaktywnego.
EN
The problem of finding a (functional) concurrent realization of a reactive system by means of labelled safe Petri net is studied. Firstly, a (functional) construction is described that leads from the category of concrete asynchronous systems introduced by Morin to the category of labelled safe Petri nets. Then, the general problem is discussed. It is indicated that in general there are no optimal solutions, i.e., that the most concurrent realizations of a reactive system need not exist. Nevertheless, a framework to support the process of building a concurrent realization of a reactive system is presented.
13
Content available remote The AltaRica formalism for describing concurrent systems
Arnold A., Point G., Griffault A., Rauzy A.
Fundamenta Informaticae
|
1999
|
Vol. 40, Nr 2,3
109-124
EN
The AltaRica formalism is designed for describing complex systems consisting of a number of interacting components. Its semantics is expressed in terms of transition systems so that a system described in this language can be analysed by any technique or tool applicable to transition systems. The components of a system have two kinds of interactions -event synchronisation, like in the synchronized product of transition systems of Arnold and Nivat, -interface coordination: with each component are associated interfaces whose values depend on the state of the component as well as on the values of interfaces of other components of the system. Another feature of AltaRica is the possibility of defining hierarchical systems: some subsystems can be encapsulated and their mutual interactions as well as their interactions with the rest of the system are supervised by a controller.
14
Content available remote Epimorphic functors
Bednarczyk M., Borzyszkowski A., Pawłowski W.
Prace Instytutu Podstaw Informatyki Polskiej Akademii Nauk
|
1998
|
nr 864
3-36
EN
The menagerie of epimorphisms in the category Cat of small categories is studied. The standard notion of a congruence on a category is generalized and used subsequently to introduce the notion of a kernel of a functor, quotient category and quotient functor. Theory of concurrent processes seems to be a natural place to look for applications of the notions and results presented here in the area of computer science. As an example we show how a construction that leads the notion of trace introduced by Mazurkiewicz can be explained within our framework.
PL
Celem pracy jest podanie charakteryzacji epimorfizmów w Cat, to jest w kategorii małych kategorii. Punktem wyjścia jest uogólnienie znanego w literaturze pojęcia kongruencji. Uogólnione kongruencje pozwalają wprowadzić pojęcie jądra funktora jako kongruencji, tudzież kategorii ilorazowej i funktora ilorazowego. Naturalnym miejscem do poszukiwania zastosowań wprowadzonych w pracy pojęć i rezultatów w informatyce teoretycznej, wydaje się być teoria procesów współbieżnych. Dla przykładu pokazujemy iż konstrukcję śladów Mazurkiewicza wyjaśnić można na gruncie prezentowanej teorii.
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