Connectivity by geodesics on a class of globally hyperbolic spacetimes

During the past years there has been a considerable amount of research related to the problem of geodesic connectedness of Lorentzian manifolds. This topic has wide applications in Physics, but for mathematicians its interest is essentially due to the peculiar di culty of this natural problem, which makes it challenging from both an analytical and a geometrical point of view. In this talk I discuss the geodesic connectedness problem on globally hyper- bolic spacetimes endowed with a complete, timelike or lightlike, Killing vector eld and a complete Cauchy hypersurface. Then I introduce the notion of open subset with convex boundary and present some applications of previous results.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

OPTION PRICING UNDER LÉVY PROCESSES: A UNIFYING FORMULA

A new option pricing formula is presented that unifies several results of the existing literature on pricing exotic options under Lèvy processes. To demonstrate the flexibility of the formula a few examples are given which provide new valuation formulas within the Lévy frameworkLévy processes, pseudo differential operators, option pricing

Methods to set transport service fees with the Apulian example of Brindisi port

Setting fees in transport service has always been particularly important in economy both under a theoretical point of view and for the aims economic policies have to achieve by means of this instrument. In this view, the issue of the European Commission Green Book in 1997 - on ports and sea infrastructures - and that of the White Book in 1998 - referring to a fair set of fees to exploit infrastructures with an approach in stages in an UE context - led again to the debate on criteria to set transport infrastructures fees, particularly for ports. This paper aims to find a motion to review taxation on shipped and unloaded goods (art. 13, paragraph 1, letter c), act of 28th January 1994, no. 84) effective in the Brindisi port, Apulia, determined with ordinance no. 1/1999. Tax revision will occur referring to last years ISTAT indexes and considering the possibility of a higher levy to Harbour Authority necessary to improve services for passengers and goods movement. Variables of port fees will be set both for passengers and goods handling. Moreover, estimating transport demand elasticity in relation to price (fee) is essential to set fees variation. To set fees other ports taxes – comparable and/or competitor with the Brindisi port - will be taken into account together with the increase in management operational costs expected in 2004.

Differentiated Networks: Equilibrium and Efficiency

We consider a model of price competition in a duopoly with product differentiation and network effects. The value of a good for a consumer is the sum of a common and an idiosyncratic component. The first captures the vertical dimension of quality, the second captures horizontal differentiation. Each consumer privately observes his own value for each good, but cannot separate the common and the idiosyncratic component. Therefore, he has incomplete information about the value of the goods for the other consumers. After firms announce prices, consumers choose simultaneously which network to join, facing a coordination problem. In the efficient allocation, both networks are active and the firm with the highest expected quality has the largest market share. To characterize the equilibrium allocation, we derive necessary and sufficient conditions for uniqueness of the equilibrium of the coordination game played by consumers for given prices. The equilibrium allocation differs from the efficient one for two reasons. First, the equilibrium allocation of consumers to the networks is too balanced, since consumers fail to internalize network externalities. Second, if access to the networks is priced by strategic firms, then the product with the highest expected quality is also the most expensive. This further reduces the asymmetry between market shares and therefore social welfare.