Sur les sous-espaces de $l_p \hat{\hat{\otimes}} l_q$

Zéro-cycles de degré un sur les espaces homogènes

We explain how to build homogeneous spaces of a connected linear algebraic group, having zero-cycles of degree one but no rational point, even on a smooth compactification. Thus, we give a negative answer to a recent question asked by Burt Totaro. Parimala ([Pa]) has independently produced such spaces over fields of the type k((t)) (for k a suitable p-adic field), which are projective varieties...

Sur les sous-groupes nilpotents du groupe de Cremona

We describe the nilpotent subgroups of the group Bir(P(C)) of birational transformations of the complex projective plane. Let N be a nilpotent subgroup of class k > 1; then either each element of N has finite order, or N is virtually metabelian.

Etat actuel de nos connaissances sur les argasidés de l'Iran

Sur Les Applications De Lattès De P

Let f be a polynomial endomorphism of degree d ≥ 2 of C k (k ≥ 2) which extends to a holomorphic endomorphism of P k. Assume that the maximal order Julia set of f is laminated by real hypersurfaces in some open set. We show that f is homogenous and is a polynomial lift of a Lattès endomorphism of P k−1 .

Itération D’applications Rationnelles Dans Les Espaces De Matrices

The iteration of rational maps is well understood in dimension 1 but less so in higher dimensions. We study some maps on spaces of matrices which present a weak complexity with respect to the ring structure. First, we give some properties of certain rational maps; the simplest example is the rational map which sends the matrix M onto M2 for which we exhibit some dynamical properties. Finally, w...