Article
Автоматическое построение распределенных систем компонентов по моделям вложенных сетей Петри
Multi-agent systems (MAS) with many levels and dynamic hierarchical structure are widely used in telecommunication, transport, social, and other fields.
Assuring correctness of such systems is an important and topical issue.
In this paper we consider modeling MAS with dynamic structure with the help of Nested Petri nets (NPNs). NPN is an extension of Petri nets within ‘nets-within-nets’ paradigm, when tokens in a Petri nets are Petri nets themselves.
Net tokens have autonomous behavior and communicate with each other.
In the model-driven software development process building a code from a designed model is the most error-prone phase.
The paper presents an algorithm for automatic translation of NPN models of MAS into systems of distributed components.
The suggested translation respects the distributed structure of source models components, preserves some important behavioral properties (such as safety, liveness, conditional liveness), and supports the fairness of the system execution.
The translation allows automating the development of distributed multi-agent systems, based on nested Petri nets models.
A translator prototype on the basis of EJB technology was implemented and tested.
Nested Petri nets (NP-nets) is an extension of Petri net formalism within the “nets-within-nets” approach, when tokens in a marking are Petri nets wich have autonomous behavior and synchronize with the system net. The formalism of NP-nets allows modeling multilevel multiagent systems with dynamic structure in a natural way. Currently there is no tool support for NP-nets simulation and analysis. The paper proposes translation of NP-nets into colored Petri nets and using CPN Tools as a virtual machine for NP-nets modeling, simulation and automatic verification.
Nested Petri nets (NP-nets) have proved to be one of the convenient formalisms for distributed multi-agent systems modeling and analysis. It allows representing multi-agent systems structure in a natural way, since tokens in the system net are Petri nets themselves, and have their own behavior. Multi-agent systems are highly concurrent. Verification of such systems with model checking method causes serious difficulties arising from the huge growth of the number of system intermediate states (state-space explosion problem). To solve this problem an approach based on unfolding system behavior was proposed in the literature. Earlier in [4] the applicability of unfolding for nested Petri nets verification was studied, and the method for constructing unfolding for safe conservative nested Petri nets was proposed. In this work we propose another method for constructing safe conservative nested Petri nets unfoldings, which is based on translation of such nets into classical Petri nets and applying standard method for unfolding construction to them. We discuss also the comparative merits of the two approaches.
The annual ACM SIGMOD/PODS Conference is a leading international forum for database researchers, practitioners, developers, and users to explore cutting-edge ideas and results, and to exchange techniques, tools, and experiences. The conference includes a fascinating technical program with research and industrial talks, tutorials, demos, and focused workshops. It also hosts a poster session to learn about innovative technology, an industrial exhibition to meet companies and publishers, and a careers-in-industry panel with representatives from leading companies.
Nested Petri nets (NP-nets) are Petri nets with net tokens - an extension of high-level Petri nets for modeling active objects, mobility and dynamics in distributed systems. In this paper we present an algorithm for translating two-level NP-nets into behaviorally equivalent Colored Petri nets with the view of applying CPN methods and tools for nested Petri nets analysis. We prove, that the proposed translation preserves dynamic semantics in terms of bisimulation equivalence.
Checking the correctness of distributed systems is one of the most difficult and urgent problems in software engineering. A combined toolset for the verification of real-time distributed systems (RTDS) is described. RTDSs are specified as statecharts in the Universal Modeling Language (UML). The semantics of statecharts is defined by means of hierarchical timed automata. The combined toolset consists of a UML statechart editor, a verification tool for model checking networks of real-time automata in UPPAAL, and a translator of UML statecharts into networks of timed automata. The focus is on the translation algorithm from UML statecharts into networks of hierarchical timed automata. To illustrate the proposed approach to the verification of RTDSs, a toy example of a real-time crossroad traffic control system is analyzed.
Nested Petri nets is an extension of Petri net formalism with net tokens for modelling multi-agent distributed systems with complex structure. Temporal logics, such as CTL, are used to state requirements of software systems behaviour. However, in the case of nested Petri nets models, CTL is not expressive enough for specification of system behaviour. In this paper we propose an extension of CTL with a new modality for specifying agents behavior. We define syntax and formal semantics for our logic, and give small examples of its usage.
A model for organizing cargo transportation between two node stations connected by a railway line which contains a certain number of intermediate stations is considered. The movement of cargo is in one direction. Such a situation may occur, for example, if one of the node stations is located in a region which produce raw material for manufacturing industry located in another region, and there is another node station. The organization of freight traffic is performed by means of a number of technologies. These technologies determine the rules for taking on cargo at the initial node station, the rules of interaction between neighboring stations, as well as the rule of distribution of cargo to the final node stations. The process of cargo transportation is followed by the set rule of control. For such a model, one must determine possible modes of cargo transportation and describe their properties. This model is described by a finite-dimensional system of differential equations with nonlocal linear restrictions. The class of the solution satisfying nonlocal linear restrictions is extremely narrow. It results in the need for the “correct” extension of solutions of a system of differential equations to a class of quasi-solutions having the distinctive feature of gaps in a countable number of points. It was possible numerically using the Runge–Kutta method of the fourth order to build these quasi-solutions and determine their rate of growth. Let us note that in the technical plan the main complexity consisted in obtaining quasi-solutions satisfying the nonlocal linear restrictions. Furthermore, we investigated the dependence of quasi-solutions and, in particular, sizes of gaps (jumps) of solutions on a number of parameters of the model characterizing a rule of control, technologies for transportation of cargo and intensity of giving of cargo on a node station.
Event logs collected by modern information and technical systems usually contain enough data for automated process models discovery. A variety of algorithms was developed for process models discovery, conformance checking, log to model alignment, comparison of process models, etc., nevertheless a quick analysis of ad-hoc selected parts of a journal still have not get a full-fledged implementation. This paper describes an ROLAP-based method of multidimensional event logs storage for process mining. The result of the analysis of the journal is visualized as directed graph representing the union of all possible event sequences, ranked by their occurrence probability. Our implementation allows the analyst to discover process models for sublogs defined by ad-hoc selection of criteria and value of occurrence probability
The geographic information system (GIS) is based on the first and only Russian Imperial Census of 1897 and the First All-Union Census of the Soviet Union of 1926. The GIS features vector data (shapefiles) of allprovinces of the two states. For the 1897 census, there is information about linguistic, religious, and social estate groups. The part based on the 1926 census features nationality. Both shapefiles include information on gender, rural and urban population. The GIS allows for producing any necessary maps for individual studies of the period which require the administrative boundaries and demographic information.
It is well-known that the class of sets that can be computed by polynomial size circuits is equal to the class of sets that are polynomial time reducible to a sparse set. It is widely believed, but unfortunately up to now unproven, that there are sets in EXPNP, or even in EXP that are not computable by polynomial size circuits and hence are not reducible to a sparse set. In this paper we study this question in a more restricted setting: what is the computational complexity of sparse sets that are selfreducible? It follows from earlier work of Lozano and Torán (in: Mathematical systems theory, 1991) that EXPNP does not have sparse selfreducible hard sets. We define a natural version of selfreduction, tree-selfreducibility, and show that NEXP does not have sparse tree-selfreducible hard sets. We also construct an oracle relative to which all of EXP is reducible to a sparse tree-selfreducible set. These lower bounds are corollaries of more general results about the computational complexity of sparse sets that are selfreducible, and can be interpreted as super-polynomial circuit lower bounds for NEXP.