Fundamenta Informaticae - Volume 51, issue 1-2

Authors: Raś, Zbigniew W. | Gupta, Shishir

Article Type: Research Article

Abstract: In papers [4,5], query answering system based on distributed knowledge mining was introduced and investigated. In paper by Ras and Wieczorkowska [3], the notion of an action rule was introduced and for its application domain e-business was taken. In this paper, we generalize the notion of action rules in a similar way to handling global queries in [4,5]. Mainly, when values of attributes for a given customer, used in action rules, can not be easily changed …by business user, definitions of these attributes are extracted from other sites of a distributed knowledge system. To be more precise, attributes at every site of a distributed knowledge system are divided into two sets: stable and flexible. Values of flexible attributes, for a given consumer, sometime can be changed and this change can be influenced and controlled by a business user. However, some of these changes (for instance to the attribute ``profit'') can not be done directly to a chosen attribute. In this case, definitions of such an attribute in terms of other attributes have to be learned. These new definitions are used to construct action rules showing what changes in values of flexible attributes, for a given consumer, are needed in order to re-classify this consumer the way business user wants. But, business user may be either unable or unwilling to proceed with actions leading to such changes. In all such cases we may search for definitions of these flexible attributes looking at either local or remote sites for help. Show more

Keywords: knowledge discovery, distributed information systems, e-commerce

Citation: Fundamenta Informaticae, vol. 51, no. 1-2, pp. 175-184, 2002

Authors: Richling, Jan | Popova-Zeugmann, Louchka | Werner, Matthias

Article Type: Research Article

Abstract: In this paper, we introduce our concept of composability and present the MSS architecture as an example for a composable architecture. MSS claims to be composable with respect to timing properties. We discuss, how to model and prove properties in such an architecture with time-extended Petrinets. As a result, the first step of a proof of composability is presented as well as a new kind of Petrinet, which is more suitable for modeling architectures like MSS.

Keywords: real time, composability, Petrinets, duration nets, π-PN

Citation: Fundamenta Informaticae, vol. 51, no. 1-2, pp. 185-200, 2002

Authors: Suraj, Zbigniew | Peters, J.F. | Rzasa, W.

Article Type: Research Article

Abstract: Decision algorithms useful in classifying meteorological volumetric radar data are the subject of described in the paper experiments. Such data come from the Radar Decision Support System (RDSS) database of Environment Canada and concern summer storms created in this country. Some research groups used the data completed by RDSS for verifying the utility of chosen methods in volumetric storm cells classification. The paper consists of a review of experiments that were made on the data from …RDSS database of Environment Canada and presents the quality of particular classifiers. The classification accuracy coefficient is used to express the quality. For five research groups that led their experiments in a similar way it was possible to compare received outputs. Experiments showed that the Support Vector Machine (SVM) method and rough set algorithms which use object oriented reducts for rule generation to classify volumetric storm data perform better than other classifiers. Show more

Keywords: rough sets, cross-validation, data mining, knowledge discovery, meteorological volumetric radar data, pattern recognition

Citation: Fundamenta Informaticae, vol. 51, no. 1-2, pp. 201-214, 2002

Authors: Varpaaniemi, Kimmo

Article Type: Research Article

Abstract: Combinatorial explosion which occurs in parallel compositions of LTSs can be alleviated by letting the stubborn set method construct on-the-fly a reduced LTS that is CFFD- or CSP-equivalent to the actual parallel composition. This article considers the problem of minimizing the number of successor states of a given state in the reduced LTS. The problem can be solved by constructing an and/or-graph with weighted vertices and by finding a set of vertices …that satisfies a certain constraint such that no set of vertices satisfying the constraint has a smaller sum of weights. Without weights, the and/or-graph can be constructed in low-degree polynomial time w.r.t. the length of the input of the problem. However, since actions can be nondeterministic and transitions can share target states, it is not known whether the weights are generally computable in polynomial time. Consequently, it is an open problem whether minimizing the number of successor states is as ``easy'' as minimizing the number of successor transitions. Show more

Keywords: LTS's, CFFD-equivalence, CSP-equivalence, stubborn sets, and/or-graphs

Citation: Fundamenta Informaticae, vol. 51, no. 1-2, pp. 215-234, 2002

Authors: Winkowski, Józef

Article Type: Research Article

Abstract: Contextual nets, or Petri nets with read arcs, are models of concurrent systems with context dependent actions. The problem of reachability in such nets consists in finding a sequence of transitions that leads from the initial marking of a given contextual net to a given goal marking. The solution to this problem that is presented in this paper consists in constructing a finite complete prefix of the unfolding of the given contextual net, that is a …finite prefix in which all the markings that are reachable from the initial marking are present, and in searching in each branch of this prefix for the goal marking by solving an appropriate linear programming problem. Show more

Keywords: contextual net, Petri net with read arcs, contextual occurrence net, branching process, unfolding, configuration, history, cut, narking, state, complete prefix, linear programming

Citation: Fundamenta Informaticae, vol. 51, no. 1-2, pp. 235-250, 2002