Hybrid approach with an expert system and a genetic algorithm to production management in the supply net

A new approach to solving production management problems in the supply net is proposed. An expert system designed to help companies in medium-term and short-term production planning is discussed. The proposed expert system considers alternative process plans for a job and outsourcing, when a bottleneck exists in the machine. The proposed hybrid system uses the output of the expert system as the input of the genetic algorithm. The output of the genetic algorithm is a near optimal schedule. The proposed method does not require any unrealistic assumptions. It can be used to solve highly complicated and non-linear functions of a realistic problem. Copyright © 2007 John Wiley & Sons, Ltd.     

Inter-local relations and trans-scaling through finance in Poland

Inter-local cooperation is difficult to measure. In Poland, however, the data-set concerning financial transfers between local government budgets (one of the most popular quantitative measures of cooperation) has never been described in scientific literature. This paper aims at contributing to fill this gap. On the basis of the budget expenditures of all Polish local governments, we applied two research methods: OLS regression and Heckman two-stage regression. The results show that the decision whether to get into cooperation, and the decision on the extent of involvement are driven by different factors.     

‘Communities of resistance’ and the use of newspaper discussion boards: Polish workers in Japanese foreign investments

This article examines the content of 200 posts on newspaper discussion boards by workers in a cluster of Japanese foreign investments in Poland. The conclusions are first, that the material experiences of workers generate a set of themes in relation to the labour process with regard to wages and working conditions, bullying and monitoring that exhibit similarities across countries. Second, we argue that an analysis of the discourse used is shaped by political and institutional conditions, which reveal national differences in how workers perceive and locate their exploitation. Finally, in relation to debates about workers’ resistance and the use of the Internet we argue that the interaction of themes related to the material experience of work are intertwined with institutionally embedded understandings of exploitation, which not only enable a shared framework for venting, but also provide the basis for a community of resistance.     

Formal and real ownership structure of the Polish economy: state-owned versus state-controlled enterprises

This article analyses the difference between the state’s formal and real shares in the Polish economy. We identify two basic types of corporate control exercised by the state over enterprises through ownership (in the case of majority ownership) and non-ownership tools (in the case of minority ownership). Consequently, we distinguish between two types of state enterprises: state-owned enterprises (SOEs) and state-controlled enterprises (SCEs). In post-communist economies, SCEs mainly originate from so-called reluctant privatisation, in which the transfer of ownership rights takes place without the appropriate transfer of control rights. We discuss the tools of non-ownership control used by the state. Our estimates of the real share of state enterprises in the Polish economy (which include both SOEs and SCEs) show that it is almost two times higher than the formal share (only SOEs). The share of state enterprises is also highest in the group of Poland’s largest and most important firms. We conclude that the real importance of state enterprises in the Polish economy is much higher than might be expected if only the formal share of state ownership is taken into account.     

Status Quo and Potential of XBRL for Business and Information Systems Engineering

The paper examines the current state of research as regards the eXtensible Business Reporting Language (XBRL) by using the literature review methodology. The results show that an empirical-quantitative research design is used most of the time. The contributions vary in substance in terms of research on XBRL and research with XBRL. Research with XBRL focuses on the development of conceptual XBRL extensions. Work on XBRL considers, for example, the changes in reporting as a result of XBRL as well as the acceptance and enforcement of financial reporting standards. The results point to open issues and are relevant for research and practice.     

An Out-of-Sample Analysis of Investment Guarantees for Equity-Linked Products

Abstract

In this paper we analyze the risk underlying investment guarantees using 78 different econometric models: GARCH, regime-switching, mixtures, and combinations of these approaches. This extensive set of models is compared with returns observed during the financial crisis in an out-of-sample analysis, bringing a new perspective to the study of equity-linked insurance. We find that despite the very good fit of recent models, too few of them are capable of consistently generating low returns over long periods, which were in fact observed empirically during the financial crisis. Moreover, tail risk measures vary significantly across models, and this emphasizes the importance of model risk. Most insurance companies are now focusing on dynamically hedging their investment guarantees, and so we also investigate the robustness of the Black-Scholes delta hedging strategy. We find that hedging errors can be very large among the top fitting models, implying that model risk must be taken into consideration when hedging investment guarantees.     

Unmeasurable characteristics in comparing economies: Poland and European Union Countries

After the recent period of economic and political change, many countries of Central and Eastern Europe are interested in integrating with the European Union. Therefore, there is considerable significance in comparative research in economic policies. One of the methods used is the taxonomic approach. During the evaluation and comparison of various national economies' development, both measurable and unmeasurable features are found in the collection of diagnostic features. For this reason, it is very important to estimate the level of research subjectivity—or the influence of unmeasurable features—on the results of comparative research. This paper proposes the methodology which makes such research possible.     

Network effects and preference heterogeneity in the case of mobile telecommunications markets

This paper demonstrates how revealed- and stated-preference analyses can be used for modeling network effects in the field of mobile telecommunications. The aim of this study was to verify if network effects may still play a role in the Polish mobile telecommunications market, measure their strength, identify their sources and variability across consumers by accounting for consumers' observable and unobservable preference heterogeneity, evaluate their monetary value to consumers, and finally, to verify if the marginal utility associated with network effects is constant. The analysis of consumers' revealed choices (currently used mobile telephone operator) allowed the identification of major differences between customer bases of incumbent and new entrant operators, and insight into the business strategies adopted in the presence of asymmetric regulation of mobile termination rates. The second part of the study—the analysis of the consumers' stated choices (made in carefully prepared and designed hypothetical choice situations, known as the choice experiments) made it possible to directly model consumers' utility functions and, in this way, investigate the nature of network effects in mobile telecommunications markets. From the results, the presence of strong network effects, which are related to the ratio of consumers' social network group using the same operator, and to the magnitude of on-net price discounts, is confirmed. These network effects can be disaggregated to pecuniary and non-pecuniary effects. Through the utilization of the random parameters multinomial logit model, consumers' observable and unobservable preference heterogeneity can be accounted for, which proved a scientifically revealing and potentially policy-relevant approach. The results might be of a particular interest to other researchers aiming at modeling consumers' preferences as well as to mobile telephone operators and regulatory authorities—it is shown that capacity for vigorous price competition between mobile operators is limited by non-price factors, which affect subscriber's choices, especially in the presence of asymmetric mobile termination rates.