The multi-triple-pole solitons for the focusing mKdV hierarchy with nonzero boundary conditions

In this paper, the general triple-pole multi-soliton solutions are proposed for the focusing modified Korteweg–de Vries (mKdV) equation with both nonzero boundary conditions (NZBCs) and triple zeros of analytical scattering coefficients by means of the inverse scattering transform. Furthermore, we also give the corresponding trace formulae and theta conditions. Particularly, we analyze some representative reflectionless potentials containing the triple-pole multi-dark-anti-dark solitons and breathers. The idea can also be extended to the whole mKdV hierarchy (e.g. the fifth-order mKdV equation, and third-fifth-order mKdV equation) with NZBCs and triple zeros of analytical scattering coefficients. Moreover, these obtained triple-pole solutions can also be degenerated to the triple-pole soliton solutions with zero boundary conditions.

Les formules des traces relatives de Jacquet–Rallis grossières

On établit les formules des traces relatives de Jacques–Rallis grossières pour les groupes linéaires et unitaires. Les deux formules sont sous la forme suivante: une somme des distributions spectrales est égale à une somme des distributions géométriques. Pour établir les développements spectraux on introduit de nouveaux opérateurs de troncature et on étudie leur propriétés. Du côté géométrique, en utilisant les applications de Cayley, les développements s’obtiennent par un argument de descente vers les espaces tangents pour lesquels les formules sont connues grâce à nos travaux précédents.We establish the coarse relative trace formulae of Jacquet–Rallis for linear and unitary groups. Both formulae are of the form: a sum of spectral distributions equals a sum of geometric distributions. In order to obtain the spectral decompositions we introduce new truncation operators and we investigate their properties. On the geometric side, by means of the Cayley transform, the decompositions are derived from a procedure of descent to the tangent spaces for which the formulae are known thanks to our previous work.

The bounded approximation property of variable Lebesgue spaces and nuclearity

In this paper we prove the bounded approximation property for variable exponent Lebesgue spaces, study the concept of nuclearity on such spaces and apply it to trace formulae such as the Grothendieck-Lidskii formula. We apply the obtained results to derive criteria for nuclearity and trace formulae for periodic operators on $\mathbb{R}^n$ in terms of global symbols.