Searching for a Solution to Program Verification=Equation Solving in CCS

International audienceUnder non-exponential discounting, we develop a dynamic theory for stopping problems in continuous time. Our framework covers discount functions that induce decreasing impatience. Due to the inherent time inconsistency, we look for equilibrium stopping policies, formulated as fixed points of an operator. Under appropriate conditions, fixed-point iterations converge to equilibrium stopping policies. This iterative approach corresponds to the hierarchy of strategic reasoning in game theory and provides “agent-specific” results: it assigns one specific equilibrium stopping policy to each agent according to her initial behavior. In particular, it leads to a precise mathematical connection between the naive behavior and the sophisticated one. Our theory is illustrated in a real options model

Bit error evaluation of optically preamplified direct detection receiver with Fabry-Perot optical filters

The error performance of a preamplified, direct detection receiver with an optical filter of the Lorentzian type is studied. The analysis takes into account the influence of the optical intersymbol interference (ISI). A closed-form expression of the moment generating function (MGF) of the decision variable is derived. Error probabilities are evaluated from the MGF using a saddlepoint approximation. The Gaussian approximation is also examined. The detection sensitivity in terms of a quantum limit is calculated. The results show that there exists an optimum optical bandwidth, the reason being a tradeoff between the effect of ISI and the spontaneous emission noise. It is also shown that the Gaussian approximation gives a good estimate of the error probability, allowing to find in a simple manner the optimum parameters of optically preamplified, direct detection receive

Técnicas de etiquetado de señales ópticas en redes de conmutación de ráfagas

En este artículo presentamos una revision de los asuntos mas importantes relacionados con las redes de conmutacion de ráfagas de señales ópticas etiquetadas (LOBS - Labeled optical burst switched) y las tecnologias que permitiran en un futuro disponer de redes totalmente ópticas. La conmutacion de ráfagas de señales ópticas etiquetadas permite de un modo rapido y con un mecanismo eficiente de enrutamiento, el direccionamiento de paquetes/ráfagas sobre redes multiplexadas por división de onda (WDM - Wavelength división multiplexing). Por otro lado, y debido a que se unifica el algoritmo de enrutamiento y tiene una baja latencia, esta tecnologia es facilmente escalable hasta rangos de Terabits.Peer Reviewe

Income segregation in monocentric and polycentric cities: Does urban form really matter?

We estimate the effect of urban spatial structure on income segregation in Brazilian cities between 2000 and 2010. Our results show that, first, local density conditions increase income segregation: the effect is higher in monocentric cities and smaller in polycentric ones. Second, the degree of monocentricity-polycentricity also affects segregation: while a higher concentration of jobs in and around the CBD decreases segregation in monocentric cities, a higher employment concentration in and around subcenters located far from the CBD decreases segregation in polycentric cities. Third, results are heterogeneous according to city size: local density does not increase segregation in small (monocentric) cities, it increases segregation in medium size cities, and it decreases segregation in large (polycentric) cities. Finally, results also differ between income groups: while local density conditions increase the segregation of the poor, a more polycentric configuration reduces the segregation of the rich