Fundamenta Informaticae

Two methods of the analysis of distorted (fuzzy) string patterns are presented. The methods are based on the use of GDPLL(k) grammars generating a large subclass of context sensitive languages. The first one utilizes error-correcting approach: a minimum distance measure is used for error-correcting parsing. The second one utilizes stochastic approach: the decision about the production to be applied in a derivation step is given according to the probability measure.

The paper introduces the formal description of a computing multi-agent system (MAS), its architecture and dynamics (sections 2–4). The optimal scheduling problem for the MAS as well as a way of its verification are presented in terms of such a model (section 5). A brief report of test results published previously in [13, 3, 4, 8] is contained in section 6.

This work focuses on the dynamic Pickup and Delivery Problem with Time Windows (PDPTW). The transport requests should be performed using the available fleet of vehicles. The vehicles move between the nodes of a road network. The aim of this work is to propose a model which allows, during a transport plan creation, to take into account predictable events. Particularly, we consider the frequency of requests at any node in the road network and the construction of vehicle routes that will allow new requests to be inserted without any significant route modification. Therefore, we construct routes that pass near the nodes where transport requests are most frequently generated.

The contribution deals with a class of intelligent decentralized systems that meet the agent paradigm. Such systems are marked by the possibility of arising critical situations, interpreted here as the threat of loss (partial or complete) of the system functionality. The work is focused on designing an overall architecture of the (sub-)system dedicated to the discovery of crises and support of anti-crisis activities. The architecture is proposed as a reference one so as it is possible to adjust it to the specificity of any particular application. As an illustration the case of a transportation system is discussed.

Rough set theory is a paradigm for approximate reasoning based on a formal mathematical basis, viz., it assumes that concepts are divided into exact and non-exact (rough) ones by means of a topological structure induced by a representation of knowledge as a classification. A classification in its most simple form is an equivalence relation on a universe of objects; the classification induces a partition topology and concepts (subsets of the universe) that are clopen are exact whereas other concepts are rough. In consequence, rough sets are represented as pairs of exact sets of the form (interior, closure).

In the paper, we propose a set theory RZF that represents formally exact and rough sets as satisfying or not a certain dichotomy based on a new form of membership in a set; this membership acquires a mereological character as it is based on containment. As a result, we propose a new form of set theory suitable as a set theory for rough sets.

Logical models for reasoning in the framework of rough set theory were proposed and studied by many researchers, among them Orłowska, Orłowska and Pawlak, Rasiowa and Skowron, Vakarelov. We exploit here models of RZF as interpretation domains for rough mereological logics: intensional logics whose truth value assignment is based on rough inclusions – basic predicates of rough mereology, a paradigm for approximate reasoning introduced by Polkowski and Skowron.

An application for those logics is proposed in semantic interpretation of vague statements forming the domain of Calculus of Perceptions proposed by Zadeh.

This paper concerns problems of applying the approach based on rough sets and rule induction to a software engineering data analysis. More precisely, we focus our interest on a software cost estimation problem, which includes predicting the effort required to develop a software system basing on values of cost factors. The case study of analysing the COCOMO data set, containing descriptions of representative historical projects, allows us to discuss how this approach could be used to: identify the most discriminatory cost factors, extract meaningful rule representation of classification knowledge from data, construct accurate rule based classifiers.

Time is one of the most important considerations in designing practical systems. The notion of time plays a vital role in performance evaluation of real-time systems. A new class of timed approximate Petri nets (TAP-nets) is proposed in the paper. This net model combines high-level Petri nets with time and uncertain information. The approach presented in the paper for modelling of uncertainty, imprecision and vagueness is based on rough set theory and fuzzy Petri nets. The TAP-nets can be used for modelling and evaluating of approximate reasoning used to build expert systems, control systems, communication systems, etc. The main advantage of modelling practical systems using the TAP-nets is that the resulting models are simple, intuitive and allow the system analyst to evaluate the performance of such system models.

Petri nets are one of well established tools in both theoretical analysis and practical modelling of concurrent systems as well as approximate reasoning. However, practical usage of Petri nets is limited by the lack of computer tools which would allow to handle large and complex nets in a comfortable way. Three things are essential for modelling and analyzing by means of Petri nets – a good editor, a simulator and a powerful analysis engine. Moreover, a program should have a graphical user interface providing an opportunity to work directly with the graphical representations of Petri nets and should be able to read and write data in formats of other popular simulators of Petri Nets.

This paper presents a set of integrated graphical Petri net tools called Petri Net system (PN-system, in short).

PN-system is a follow – up on PN-tools. This system can be used for constructing, editing and analyzing of different classes of Petri nets. PN-system is enhanced with fuzzy and adaptive fuzzy Petri nets' modules which allow to perform fuzzy reasoning automatically. It has got a graphical user interface. Moreover, PN-system can cooperate with the ROSECON system which is an original software tool for discovering concurrent models from data tables.

PN-system runs on IBM PC platform under MS Windows operating system.

This paper deals with reconstruction of net models of concurrent systems described by information systems changing in time. Constructed net models have the form of coloured Petri nets. Resulting nets are constructed on the basis of decomposed information systems. In many practical cases, a description of modelled systems changes in time. New knowledge about structures and behaviours of systems appears. When new descriptions appear, the net models should be changed taking into consideration the new knowledge. An approach to reconstruction of net models is presented here. One of many possible cases is considered, i.e., when the new global state of the modelled system appears. The ability to compute reducts and components of a new information system, being a new description of a modelled system, in an efficient way is important for reconstruction. Therefore, some propositions and corollaries useful to compute reducts of a new information system on the basis of reducts of an old information system are given. These propositions and corollaries are the basis to formulate algorithms for computing new reducts and components. Moreover, a way to determine the cost of the reconstruction of a net model is given. The cost of the reconstruction is treated as the cost of adding new functional modules, communication lines or their modifications. The discussed approach to model reconstruction extends and refines that proposed by Z. Suraj in 1998. An example is given in this paper to illustrate the presented idea.