Informatica

This paper aims to extend fuzzy MULTIMOORA with linguistic reasoning and group decision-making (MULTIMOORA-FG). The new method consists of the three parts, namely the fuzzy Ratio System, the fuzzy Utopian Reference Point, and the fuzzy Full Multiplicative Form offering a robust comparison of alternatives against multiple objectives. In addition, MULTIMOORA-FG is designed to deal with triangular fuzzy numbers which, in turn, can resemble linguistic variables. MULTIMOORA-FG is a proper instrument for linguistic reasoning under fuzzy environment. In our study an application of personnel selection illustrates the group decision-making procedure according to MULTIMOORA-FG. Given the uncertainties peculiar of personnel selection, the application of multi-objective decision making (MODM) is required in this area. Fuzzy MULTIMOORA enables to aggregate subjective assessments of the decision-makers and thus offer an opportunity to perform a more robust personnel selection. The committee decided to consider eight qualitative characteristics expressed in linguistic variables. A numerical example exhibited possibilities for improvement of human resources management or any other business decision-making by applying MULTIMOORA-FG.

Regarding the complexity of actual software systems, including web portals, it is becoming more and more difficult to develop software systems such that their real usage will satisfy their intended usage. To tackle this problem, we can compare the a priori assumptions about how the system should be used with the actual user behavior in order to decide how the system could be improved. For this aim, we propose to employ the same formalism to express the intended usage, the web portal model and the real usage extracted from system usage traces by data mining algorithms. Inspired from BioCham, we propose to use temporal logic and Kripke structure as such a common formalism.

The emergence of the Semantic Web have revived the interest in knowledge engineering and ontologies. Different paradigms often share challenges and solutions, and can complement and mutually improve each other. This paper presents a simple and agile integration of ontologies and programming on a small scale, and in a down-to-Earth manner by incorporating the ontology paradigm into a mainstream programming environment. The approach is based on metaprogramming, which has been used to internalize the ontology modeling paradigm into the Clojure language. The resulting DSL, Magic Potion, is implemented in Cojure and blends ontology, functional, object-oriented and concurrent paradigms, which is suitable for general-purpose domain modeling, from technology enhanced learning to business.

A logistics system that involves a supplier who produces and delivers a single product and a buyer who receives and sells the product to the final customers was analyzed. A mathematical model was developed to describe the behavior of the system and to derive the optimal cycle length and order-up-to levels for the two parties. An analysis of the obtained results revealed that the methods were able to determine the optimal control parameters for each party in a short time frame. A coordination mechanism based on the optimal policies was ultimately proposed so that each party benefits more than if they use their own optimal control policy.

In this paper we describe possible approaches how to store XML data, which is a key aspect for their further processing. One popular technique for managing XML data is to map the data to an existing database system, e.g., to the relational or object-relational database management system. We describe possible ways how to store XML data in relational databases, because relational systems are still widely used for various purposes, including XML data management. But XML data are trees, not tables, so the main focus of this article is oriented to native XML databases. We describe general properties of such kind of databases and, in particular, explain possible solutions on two experimental native XML database management systems – ExDB and CellStore. Both have been proposed, implemented and optimized in our research groups in recent years for experimental purposes.

The notion of general backlash is introduced where instead of the straight lines determining the upward and downward parts of backlash characteristic general curves are considered. An analytic form of general backlash characteristic description is proposed, which is based on appropriate switching and internal functions. Consequently, this multi-valued mapping is represented by one difference equation. All the parameters in the equation describing this hard nonlinearity are separated; hence the general backlash identification can be solved as a quasi-linear problem using an iterative parameter estimation method with internal variable estimation. Also the identification of cascaded systems consisting of a general input backlash followed by a linear dynamic system is presented. Simulation studies of general backlash identification and that of cascaded systems with general input backlash are included.

Fuzzy identity based encryption (FIBE), proposed by Sahai and Waters, is a new kind of identity based encryption. It allows users with identity w can decrypt ciphertext for w' if and only if w is close enough to w'. Recently, Ren et al. proposed a new FIBE scheme and claimed it is fully CCA2 secure in the standard model with a tight reduction. However, in this paper we will show that their scheme is not correct. Furthermore, the key generation process of their scheme cannot resist the collusion attack, which is a basic security requirement for FIBE. At last, we propose a new fully secure FIBE scheme based on the Sahai–Waters FIBE scheme and prove its security by using the “dual system encryption” technique.

An authenticated group key exchange (AGKE) protocol allows participants to construct a common key and provide secure group communications in cooperative and distributed applications. Recently, Choi et al. proposed an identity (ID)-based authenticated group key exchange (IDAGKE) protocol from bilinear pairings. However, their protocol suffered from an insider colluding attack because it didn't realize the security issue of withstanding insider attacks. Withstanding insider attacks mean that it can detect whether malicious participants exist in the group key exchange protocol. Nevertheless, an AGKE protocol resistant to insider attacks is still unable to find “who are malicious participants”. In this paper, we propose an ID-based AGKE protocol with identifying malicious participants. In our protocol, we use a confirmed computation property to achieve identifying malicious participants. Certainly, it is also secure against insider attacks. In the random oracle model and under related mathematical hard problems, we prove that the proposed protocol a secure AGKE protocol with identifying malicious participants.