We give a topological criterion for the minimality of the strong unstable (or stable) foliation of robustly transitive partially hyperbolic diffeomorphisms.

As a consequence we prove that, for $3$-manifolds, there is an open and dense subset of robustly transitive diffeomorphisms (far from homoclinic tangencies) such that either the strong stable or the strong unstable foliation is robustly minimal.

We also give a topological condition (existence of a central periodic compact leaf) guaranteeing (for an open and dense subset) the simultaneous minimality of the two strong foliations.

AMS 2000 Mathematics subject classification: Primary 37D25; 37C70; 37C20; 37C29

Cet article est le résultat d'une relecture de la démonstration de la conjecture {\fontencoding{U}\fontfamily{lasy}\selectfont(\kern-0.20em(\kern.175em}faiblement admissible implique admissible{\fontencoding{U}\fontfamily{lasy}\selectfont\kern.175em)\kern-0.20em)} par J.-M. Fontaine et l'auteur. On donne une version renforcée de l'un des ingrédients (le {\fontencoding{U}\fontfamily{lasy}\selectfont(\kern-0.20em(\kern.175em}lemme fondamental{\fontencoding{U}\fontfamily{lasy}\selectfont\kern.175em)\kern-0.20em)}) de cette démonstration, ce qui nous amène à introduire un corps non commutatif gigantesque $\mathfrak{C}$, de centre $\textbf{Q}_p$ et contenant un corps $C$ algébriquement clos et complet pour la norme $p$-adique comme sous-corps commutatif maximal. Un peu {\fontencoding{U}\fontfamily{lasy}\selectfont(\kern-0.20em(\kern.175em}d'algèbre linéaire{\fontencoding{U}\fontfamily{lasy}\selectfont\kern.175em)\kern-0.20em)} sur ce corps mène à l'introduction de la catégorie des Espaces (avec un E majuscule) de Banach de dimension finie, et la conjecture {\fontencoding{U}\fontfamily{lasy}\selectfont(\kern-0.20em(\kern.175em}faiblement admissible implique admissible{\fontencoding{U}\fontfamily{lasy}\selectfont\kern.175em)\kern-0.20em)} se réduit alors à un calcul de dimensions d'objets de cette catégorie.

AMS 2000 Mathematics subject classification: Primary 11S

An exact control theorem is proven for nearly ordinary $p$-adic automorphic forms on symplectic and unitary groups over totally real fields if the algebraic group is split at $p$. In particular, a given nearly ordinary holomorphic Hecke eigenform can be lifted to a family of holomorphic Hecke eigenforms indexed by weights of the standard maximal split torus of the group. Their $q$-expansion coefficients are Iwasawa functions on the Iwasawa algebra of ${\mathbb{Z}}_p$-points of the split torus. The method is applicable to any reductive algebraic groups yielding Shimura varieties of PEL type under mild assumptions on the existence of integral toroidal compactification of the variety. Even in the Hilbert modular case, the result contains something new: freeness of the universal nearly ordinary Hecke algebra over the Iwasawa algebra, which eluded my scrutiny when I studied general theory of the $p$-adic Hecke algebra in the 1980s.

AMS 2000 Mathematics subject classification: Primary 11F03; 11F30; 11F33; 11F41; 11F60; 11G15; 11G18

This is the first of three articles designed to stabilize the global trace formula. The results apply to any group for which the fundamental lemma (and its variants for weighted orbital integrals) is valid. The main purpose of this paper is to establish a series of expansions that are parallel to the expansions in the trace formula. We shall also formulate the local and global theorems required to interpret the terms in these expansions. The proofs of the theorems will be given in the subsequent two articles. The expansions of this paper will then yield both a stable trace formula, and a decomposition of the ordinary trace formula into a linear combination of stable trace formulae.

AMS 2000 Mathematics subject classification: Primary 22E55. Secondary 11R39

Let $X$ be a compact surface such that $Y\hookrightarrow X$ as a separating, strictly pseudoconvex, real hypersurface;

$$ X\setminus Y=X_+\sqcup X_-, $$

where $X_{+}$ ($X_-$) is the strictly pseudoconvex (pseudoconcave) component of the complement. Suppose further that $X_-$ contains a positively embedded, compact curve $Z$. Under cohomological hypotheses on $(X_-,Z)$ we show that if $\dbarb'$ is a sufficiently small, embeddable deformation of the CR-structure on $Y$, then

$$ \mathrm{R-ind}(\bar{\partial}_{b},\bar{\partial}_{b}')\geq-[\dim H^{0,2}(X_-)+\dim H^0(Z,\mathcal{O}_Z)]. $$

This implies that the set of small, embeddable deformations of the CR-structure on $Y$ is closed, in the $\mathcal{C}^{\infty}$-topology on the set of all deformations.

AMS 2000 Mathematics subject classification: Primary 32V15; 32V30. Secondary 32G07; 32W10; 32W05

The notion of gluing of abelian categories was introduced in a paper by Kazhdan and Laumon in 1988 and studied further by Polishchuk. We observe that this notion is a particular case of a general categorical construction.

We then apply this general notion to the study of the ring of global differential operators $\mathcal{D}$ on the basic affine space $G/U$ (here $G$ is a semi-simple simply connected algebraic group over $\mathbb{C}$ and $U\subset G$ is a maximal unipotent subgroup).

We show that the category of $\mathcal{D}$-modules is glued from $|W|$ copies of the category of $D$-modules on $G/U$ where $W$ is the Weyl group, and the Fourier transform is used to define the gluing data. As an application we prove that the algebra $\mathcal{D}$ is Noetherian, and get some information on its homological properties.

AMS 2000 Mathematics subject classification: Primary 13N10; 16S32; 17B10; 18C20

A necessary and sufficient geometric condition is established for the Kohn Laplacian to be hypoelliptic, modulo its nullspace, for boundaries of arbitrary infinitely differentiable pseudoconvex tube domains in two complex variables. Hypoellipticity is also proved to be equivalent to validity of a superlogarithmic estimate, for this special class of structures.

AMS 2000 Mathematics subject classification: Primary 32W05; 32T27. Secondary 35J70.

In this paper, we construct explicitly endoscopic representations of $\widetilde{\mathrm{Sp}}_{2n}$, the metaplectic cover of a symplectic group of rank $n$. We do this in the automorphic case, and also in the local case, over a $p$-adic field.

AMS 2000 Mathematics subject classification: Primary 11F70

We show that a continuous, odd, regular (non-exceptional), ordinary, irreducible, two-dimensional, $l$-adic representation of the absolute Galois group of the rational numbers is modular over some totally real field. We deduce that it occurs in the $l$-adic cohomology of some variety over the rationals and that its $L$-function has meromorphic continuation to the whole complex plane and satisfies the expected functional equation.

AMS 2000 Mathematics subject classification: Primary 11F80. Secondary 11G40

Segre proved that a smooth cubic surface over $Q$ is unirational if and only if it has a rational point. We prove that the result also holds for cubic hypersurfaces over any field, including finite fields.

AMS 2000 Mathematics subject classification: Primary 14G05; 14G15. Secondary 11G25; 11D25

We consider the inverse connection problem consisting of determining a gauge field on $\mathbb{R}^d$ from its non-abelian Radon transform along oriented straight lines. The determination is considered modulo gauge transformations. Our results include: global uniqueness theorems for $d\geq3$, new local uniqueness theorems for $d=2$, constructive proofs (i.e. proofs containing reconstruction procedures), counterexamples to the global uniqueness for $d=2$, a reduction to the attenuated X-ray transform.

AMS 2000 Mathematics subject classification: Primary 53C65; 81U40

We prove that given a convex Jordan curve $\varGamma\subset\{x_3=0\}$, the space of properly embedded minimal annuli in the half-space $\{x_3\geq0\}$, with boundary $\varGamma$ is diffeomorphic to the interval $[0,\infty)$. Moreover, for a fixed positive number $a$, the exterior Plateau problem that consists of finding a properly embedded minimal annulus in the upper half-space, with finite total curvature, boundary $\varGamma$ and a catenoid type end with logarithmic growth $a$ has exactly zero, one or two solutions, each one with a different stability character for the Jacobi operator.

AMS 2000 Mathematics subject classification: Primary 53A10. Secondary 49Q05; 53C42

In this paper we will study solution pairs $(u,D)$ of the minimal surface equation defined over an unbounded domain $D$ in $R^2$, with $u=0$ on $\partial D$. It is well known that there are severe limitations on the geometry of $D$; for example $D$ cannot be contained in any proper wedge (angle less than $\pi$). Under the assumption of sublinear growth in a suitably strong sense, we show that if $u$ has order of growth $\alpha$ in the sense of complex variables, then the ‘asymptototic angle’ of $D$ must be at least $\pi/\alpha$. In particular, there are at most two such solution pairs defined over disjoint domains. If $\alpha<1$ then $u$ cannot change sign and there is no other disjoint solution pair. This result is sharp as can be seen by a suitable piece of Enneper’s surface which has order $\alpha=\tfrac{2}{3}$ and asymptotic angle $\tfrac{3}{2}\pi$.

AMS 2000 Mathematics subject classification: Primary 35J60; 53A10

Nori’s connectivity theorem compares the cohomology of $X\times B$ and $Y_B$, where $Y_B$ is any locally complete quasiprojective family of sufficiently ample complete intersections in $X$. When $X$ is the projective space, and we consider hypersurfaces of degree $d$, it is possible to give an explicit bound for $d$, sufficient to conclude that the Connectivity Theorem holds. We show that this bound is optimal, by constructing for lower $d$ classes on $Y_B$ not coming from the ambient space. As a byproduct we get the non-triviality of the higher Chow groups of generic hypersurfaces of degree $2n$ in $\mathbb{P}^{n+1}$.

AMS 2000 Mathematics subject classification: Primary 14C25; 14D07; 14J70

We construct embedded periodic minimal surfaces with planar ends. We use the Weierstrass representation and solve the period problem using the implicit function theorem at a singular point.

AMS 2000 Mathematics subject classification: Primary 53A10

The integrable model corresponding to the $\mathcal{N}=2$ supersymmetric SU$(N)$ gauge theory with matter in the symmetric representation is constructed. It is a spin chain model, whose key feature is a new twisted monodromy condition.

AMS 2000 Mathematics subject classification: Primary 53D30; 53D20. Secondary 37J35

Let $G$ be a Lie groupoid over $M$ such that the target-source map from $G$ to $M\times M$ is proper. We show that, if $\mathcal{O}$ is an orbit of finite type (i.e. which admits a proper function with finitely many critical points), then the restriction $G|_\mathcal{U}$ of $G$ to some neighbourhood $\mathcal{U}$ of $\mathcal{O}$ in $M$ is isomorphic to a similar restriction of the action groupoid for the linear action of the transitive groupoid $G|_\mathcal{O}$ on the normal bundle $N\mathcal{O}$. The proof uses a deformation argument based on a cohomology vanishing theorem, along with a slice theorem which is derived from a new result on submersions with a fibre of finite type.

AMS 2000 Mathematics subject classification: Primary 58H05. Secondary 57R99