Soient $X$ une variété algébrique complexe, lisse, irréductible, $E$ et $F$ deux espaces vectoriels complexes de dimension finie et $\mu$ un morphisme de $X$ dans l’espace Lin$(E,F)$ des applications linéaires de $E$ dans $F$. Pour $x\in X$, on note $E\left(x\right)$ et $x·E$ le noyau et l’image de $\mu \left(x\right)$, ${\overline{\mu }}_x$ le morphisme de $X$ dans Lin$\left(E\right(x),F/(x·E\left)\right)$ qui associe à $y$ l’application linéaire $v\mapsto \mu \left(y\right)\left(v\right)+x·E$. Soit i${}_{\mu }$ la dimension minimale de $E\left(x\right)$. On dit que $\mu$ ala propriété $\left(𝐑\right)$ en $x$si i${}_{{\overline{\mu }}_x}$ est inférieur à i${}_{\mu }$. Soient $F^{*}$ le dual de $F$, S$\left(F\right)$ l’algèbre symétrique de $F$, ${ℐ}_{\mu }$ l’idéal de ${𝒪}_X{\otimes }_{ℂ}\mathrm{S}\left(F\right)$ engendré par...

Chevalley’s theorem states that every smooth connected algebraic group over a perfect field is an extension of an abelian variety by a smooth connected affine group. That fails when the base field is not perfect. We define a pseudo-abelian variety over an arbitrary field $k$ to be a smooth connected $k$-group in which every smooth connected affine normal $k$-subgroup is trivial. This gives a new point of view on the classification of algebraic groups: every smooth connected group over a field is an extension...

We give a classification of pseudo-Riemannian weakly symmetric manifolds in dimensions $2$ and $3$, based on the algebraic approach of such spaces through the notion of a pseudo-Riemannian weakly symmetric Lie algebra. We also study the general symmetry of reductive $3$-dimensional pseudo-Riemannian weakly symmetric spaces and particularly prove that a $3$-dimensional reductive $2$-fold symmetric pseudo-Riemannian manifold must be globally symmetric.

For any pair E,F of pseudotopological vector spaces, we endow the space L(E,F) of all continuous linear operators from E into F with a pseudotopology such that, if G is a pseudotopological space, then the mapping L(E,F) × L(F,G) ∋ (f,g) → gf ∈ L(E,G) is continuous. We use this pseudotopology to establish a result about differentiability of certain operator-valued functions related with strongly continuous one-parameter semigroups in Banach spaces, to characterize von Neumann algebras, and to establish...

In this article we use the expansion for biquantization described in [7] for the case of symmetric spaces. We introduce a function of two variables $E(X,Y)$ for any symmetric pairs. This function has an expansion in terms of Kontsevich’s diagrams. We recover most of the known results though in a more systematic way by using some elementary properties of this $E$ function. We prove that Cattaneo and Felder’s star product coincides with Rouvière’s for any symmetric pairs. We generalize some of Lichnerowicz’s...

We investigate the vertical version of the Sato-Tate conjecture for some GL₂ automorphic representations over totally real fields with specified local components at a finite set of finite places.

Let $\Lambda$ be a subgroup of an arithmetic lattice in $\mathrm{SO}(n+1,1)$. The quotient ${ℍ}^{n+1}/\Lambda$ has a natural family of congruence covers corresponding to ideals in a ring of integers. We establish a super-strong approximation result for Zariski-dense $\Lambda$ with some additional regularity and thickness properties. Concretely, this asserts a quantitative spectral gap for the Laplacian operators on the congruence covers. This generalizes results of Sarnak and Xue (1991) and Gamburd (2002).

In this paper we show that the multiplicities of holomorphic discrete series representations relative to reductive subgroups satisfy the credo “quantization commutes with reduction”.

We consider Poisson pencils, each generated by a linear Poisson-Lie bracket and a quadratic Poisson bracket corresponding to a so-called Reflection Equation Algebra. We show that any bracket from such a Poisson pencil (and consequently, the whole pencil) can be restricted to any generic leaf of the Poisson-Lie bracket. We realize a quantization of these Poisson pencils (restricted or not) in the framework of braided affine geometry. Also, we introduce super-analogs of all these Poisson pencils and...

We develop the basic theory of the Weyl symbolic calculus of pseudodifferential operators over the $p$-adic numbers. We apply this theory to the study of elliptic operators over the $p$-adic numbers and determine their asymptotic spectral behavior.