Heterogeneous determinants of local unemployment in Poland

We identify determinants of large disparities in local unemployment rates across Poland. Using an extensive panel data-set on the NUTS-4 level (i.e. the poviats level, or districts or counties level) we examine a wide range of determinants of local unemployment. Our research examines two groups of the determinants: one related to equilibrium theory and the other related to disequilibrium theory of local unemployment. We find that demographics, education and sectoral employment composition exert a stronger impact over rates of local unemployment than various demand factors. The impact of the determinants, while robust for outliers, is not homogeneous across Polish regions. In particular, in the most depressed local labour markets, skill improvement programmes do not appear to work and unemployment rates are relatively less responsive to investment. Our research suggests that there is no easy cure for local unemployment in Poland, but a few policies have the potential to slightly reduce existing disparities.     

Applying free random variables to random matrix analysis of financial data. Part I: The Gaussian case

We apply the concept of free random variables to doubly correlated (Gaussian) Wishart random matrix models, appearing, for example, in a multivariate analysis of financial time series, and displaying both inter-asset cross-covariances and temporal auto-covariances. We give a comprehensive introduction to the rich financial reality behind such models. We explain in an elementary way the main techniques of free random variables calculus, with a view to promoting them in the quantitative finance community. We apply our findings to tackle several financially relevant problems, such as a universe of assets displaying exponentially decaying temporal covariances, or the exponentially weighted moving average, both with an arbitrary structure of cross-covariances.     

An advanced multimedia infrastructure for WWW-based information systems

We present an advanced multimedia infrastructure that integrates continuous real-time media streams within the WWW. This new service architecture focuses on advanced facilities for dealing with multimedia contents. A mediation server is at the heart of the infrastructure. It organizes and structures the multimedia information space. In addition to simple services for accessing and delivering multimedia data, it provides new functionalities for filtering and querying multimedia content. Content servers and on-line sources deliver media streams integrated within synchronized multimedia presentations. We think that the infrastructure will offer new opportunities for WWW-based information systems and electronic commerce. This revised version was published online in June 2006 with corrections to the Cover Date.     

Investment and Finance in de novo private firms: Empirical Results from the Czech Republic, Hungary and Poland

In this paper we use a survey of 281 Czech, Hungarian and Polish newly-established small private firms in order to shed some light on the constraints these firms face in the credit market. The results of our survey show that imperfections in capital markets in Central European economies do not seem to actually inhibit the growth of new private firms. Credit markets do exist for de novo private firms in the three Central European transition economies studied, and they provide quite a large amount of financing from an early stage of the existence of firms. Financial intermediation works reasonably well as far as de novo private firms are concerned: loss-making de novo firms have a lower probability of getting credit than profitable ones. Banks protect themselves against the risk of a deteriorating pool of borrowers by requiring collateral for their loans. We do not find convincing evidence concerning the existence of adverse selection. Loss-making firms are not ready to pay higher interest rates than profitable firms and are not more likely to ask for credit than profitable firms.     

A Bayesian method of combining judgmental and model-based density forecasts

This paper introduces a formal method of combining expert and model density forecasts when the sample of past forecasts is unavailable. It works directly with the expert forecast density and endogenously delivers weights for forecast combination, relying on probability rules only. The empirical part of the paper illustrates how the framework can be applied in forecasting US inflation by mixing density forecasts from an autoregressive model and the Survey of Professional Forecasters.     

Microscopic spin model for the stock market with attractor bubbling on scale-free networks

A multi-agent spin model for changes of prices in the stock market based on the Ising-like cellular automaton with interactions between traders randomly varying in time is investigated by means of Monte Carlo simulations. The structure of interactions has topology of scale-free networks with degree distributions obeying a power scaling law with various scaling exponents. The scale-free networks are obtained as growing networks where new nodes (agents) are linked to the existing ones according to a preferential attachment rule with an initial attractiveness ascribed to each node. In certain ranges of parameters, depending on the exponent in the degree distribution, the time series of the logarithmic price returns exhibit intermittent bursting typical of volatility clustering, and the tails of the distributions of returns obey a power scaling law with exponents comparable to those obtained from the empirical data. The distributions of returns show also dependence on the number of agents, in particular in the case of networks with the scaling exponents of the degree distributions typical of the social and communications networks.     

Collusion under monitoring of sales

Collusion under imperfect monitoring is explored when firms' prices are private information and their quantities are public information; such an information structure is consistent with several recent price‐fixing cartels, such as those in lysine and vitamins. For a class of symmetric oligopoly games, it is shown that symmetric equilibrium punishments cannot sustain any collusion. An asymmetric punishment is characterized that does sustain collusion and it has firms whose sales exceed their quotas compensating those firms with sales below their quotas. In practice, cartels could have performed such transfers through sales among the cartel members.     

On discounted dynamic programming with unbounded returns

In this paper, we apply the idea of k-local contraction of Rincón-Zapatero and Rodriguez-Palmero (Econometrica 71:1519–1555, 2003; Econ Theory 33:381–391, 2007) to study discounted stochastic dynamic programming models with unbounded returns. Our main results concern the existence of a unique solution to the Bellman equation and are applied to the theory of stochastic optimal growth. Also a discussion of some subtle issues concerning k-local and global contractions is included.     

The closedness of the free-disposal hull of a production set

Summary Assume thatL is a topological vector lattice andY is a closed subset ofL ₊ ×R ^N, whereR ^N denotes theN-dimensional Euclidean space. It is shown that the setY–L ₊ ×R ₊ ^N is closed ifY has appropriate monotonicity properties. The result is applicable to the case ofL equal toL with the Mackey topology, (L ,L ¹).