We give a contribution about the study of homogeneous pseudoRiemannian structures on a type of homogeneous spaces, namely, the pseudo-Riemannian generalized symmetric spaces of low dimensions. It is well known that generalized symmetric Riemannian spaces admit homogeneous structures of the class T2 ⊕ T3. The same property holds in the pseudo-Riemannian context. The aim of the present paper is t...

We give an equivalent condition for the existence of a semi-conjugacy to an irrational rotation for conservative homeomorphisms of the two-torus. This leads to an analogue of Poincaré's classification of circle homeomorphisms for conservative toral homeomor-phisms with unique rotation vector and a certain bounded mean motion property. For minimal toral homeomorphisms, the result extends to arbi...

Self-consistent dynamical approximations for strongly correlated fermion systems are particularly successful in capturing the dynamical competition of local correlations. In these, the effect of spatially extended degrees of freedom is usually only taken into account in a mean field fashion or as a secondary effect. As a result, critical exponents associated with phase transitions have a mean f...

Article history: Received 13 August 2010 Received in revised form 12 July 2012 Accepted 17 July 2012 Available online 23 July 2012 We use data from the US airline industry to investigate whether firms that are under bankruptcy protection, as well as these firm's product market rivals, change the quality of the products they offer. We measure the quality of the services offered by a carrier usin...

We discuss the problem of the separation of total correlations in a given quantum state into entanglement, dissonance, and classical correlations using the concept of relative entropy as a distance measure of correlations. This allows us to put all correlations on an equal footing. Entanglement and dissonance, whose definition is introduced here, jointly belong to what is known as quantum disco...

We compute the von Neumann dimensions of the kernels of adjacency operators on free lamplighter groups and show that they are irrational, thus providing an elementary constructive answer to a question of Atiyah.

We present a theory for the coagulation reaction A+A-->A for particles moving subdiffusively in one dimension. Our theory is tested against numerical simulations of the concentration of A particles as a function of time ("anomalous kinetics") and of the interparticle distribution function as a function of interparticle distance and time. We find that the theory captures the correct behavior asy...

In string gas cosmology, the extra dimensions of the underlying theory are kept at a microscopic scale by a gas of strings. In the matter-dominated era, however, dust pressure can lead to oscillations of the extra dimensions and to acceleration in the three visible dimensions, even with a vanishing cosmological term. We review the resulting oscillating expansion history, that provides an accept...