We consider a system of fermions with a quasi-random almost-Mathieu disorder interacting through a many-body short range potential. We establish exponential decay of the zero temperature correlations, indicating localization of the interacting ground state, for weak hopping and interaction and almost everywhere in the frequency and phase; this extends the analysis in [17] to chemical potentials...

We consider the Schrr odinger equation for a class of two-level atoms in a quasi-periodic external eld for large coupling, i.e., for which the energy diierence 2 between the unperturbed levels is suuciently small. We show that this equation has a solution in terms of a formal power series in , with coeecients which are quasi-periodical functions of the time, in analogy to the Lindstedt-Poincar ...

It is proved that if an algebra R over a field can be endowed with a pointed and finite-dimensional .nfiltration such that the associated .n-graded algebra T is semi-commutative, then R is left and right finitely partitive. In order to do this, a multi-variable Poincare! series for every finitely generated graded T-module is considered and it is shown that this Poincare! series is a rational fu...

To continue a branch of homoclinic solutions starting from a Bogdanov–Takens (BT) point in parameter and state space, one needs a predictor based on asymptotics for the bifurcation parameter values and the corresponding small homoclinic orbits in the phase space. We derive two explicit asymptotics for the homoclinic orbits near a generic BT point. A recent generalization of the Lindstedt–Poinca...

This article reviews the construction and some applications of twisted Poincare-covariant quantum fields on Moyal plane. The Drinfeld twist, which plays a key mathematical role in this construction, is then applied to case discrete groups, with view geons gravity. Poincare-twisted can also be study CMB anisotropies, corrections power spectrum are used put constraints spacetime noncommutativity....

For M and N closed oriented connected smooth manifolds of the same dimension, we consider the mapping space Map(M, N ; f) of continuous maps homotopic to f : M → N . We will show that the evaluation map from the space of maps to the manifold N induces a nontrivial homomorphism on the fundamental group only if the self coincidence number of f , denoted Λf,f , equals zero. Since Λf,f is equal to ...