Let $k$ be a perfect field of a positive characteristic $p, K$ – the fraction field of the ring of Witt vectors $W(k)$. Let $X$ be a smooth and proper scheme over $W(k)$. We present a candidate for a cohomology theory with coefficients in crystalline local systems: $p$-adic étale local systems on $X_K$ characterized by associating to them so called Fontaine-crystals on the crystalline site of the special fiber $X_k$. We show that this cohomology satysfies a duality theorem.

The representation theory of polynomial growth strongly simply connected finite dimensional algebras over an algebraically closed field is established.

The cohomology ring of the moduli space $M(n,d)$ of semistable bundles of coprime rank $n$ and degree $d$ over a Riemann surface $M$of genus $g \geqslant 2$ has again proven a rich source of interest in recent years. The rank two, odd degree case is now largely understood. In 1991 Kirwan [8] proved two long standing conjectures due to Mumford and to Newstead and Ramanan. Mumford conjectured that a certain set of relations form a complete set; the Newstead-Ramanan conjecture involved the vanishing of the Pontryagin ring. The Newstead–Ramanan conjecture was independently proven by Thaddeus [15] as a corollary to determining the intersection pairings. As yet though, little work has been done on the cohomology ring in higher rank cases. A simple numerical calculation shows that the Mumford relations themselves are not generally complete when $n>2$. However by generalising the methods of [8] and by introducing new relations, in a sense dual to the original relations conjectured by Mumford, we prove results corresponding to the Mumford and Newstead-Ramanan conjectures in the rank three case. Namely we show (Sect. 4) that the Mumford relations and these ‘dual’ Mumford relations form a complete set for the rational cohomology ring of $M(3,d)$ and show (Sect. 5) that the Pontryagin ring vanishes in degree$12g-8$ and above.

The main goal of this Letter is to give a new proof of a result conjectured by D. De George and N. Wallach and proved by P. Delorme and to extend it to the $S$-arithmetic setting. The proof is based on a density principle.

Abstract. Explicit models are constructed for irreducible *-representations of the quantised universal enveloping algebra $U_q({\frak g}{\frak l}(n))$. The irreducible decomposition of these modules with respect to the subalgebra $U_q({\frak g}{\frak l}(n-1))$ is given, and the corresponding spherical and associated spherical elements are determined in terms of little $q$-Jacobi polynomials. This leads to a proof of an addition theorem for the spherical elements, the so-called $q$-disk polynomials.

We study a family of K3 surfaces which have a big automorphism group. We begin with generalisations of Silverman's results: construction of canonical heights, density of rational points in one orbit,… We continue the study in estimating the density of rational points on the orbiting rational curves; this estimate is compatible with Batyrev–Manin conjecture. Moreover we settle, under more geometric hypothesis, the number of rational points of such surfaces of bounded height.

In this paper, we study representations of a Galois group of a local field absolutely unramified whose residue field is perfect of characteristic $p$ and give two ways of recognize crystalline representations with weights between $r$ and $r+p-1$. The first one is the description of terms of weakly admissible filtered modules proved by J.-M. Fontaine and G. Laffaille (Ann Sc ENS 1982): here a new proof of this result is proposed (second chapter). The second criterion (third chapter) is the equivalence between crystalline representations with weights between $r$ and $r+p-1$ and representations of finite ‘cr-height’ ${\leqslant} p-1$, result announced by J.-M. Fontaine in a paper edited a few years ago where he introduced the category of $(\varphi, \Gamma)$-modules.

We proove an analogue of the Beilinson-Bernstein Theorem, in the case of the projective space, for the ring of arithmetical differential operators introduced by P. Berthelot.

Let $G$ be a complex, semisimple, simply connected algebraic group with Lie algebra ${\frak g}$. We extend scalars to the power series field in one variable ${\rm C}((\pi))$, and consider the space of Iwahori subalgebras containing a fixed nil-elliptic element of ${\frak g} \otimes {\rm C}((\pi))$, i.e. fixed point varieties on the full affine flag manifold. We define representations of the affine Weyl group in the homology of these varieties, generalizing Kazhdan and Lusztig's topological construction of Springer's representations to the affine context.

Crystal base of the level 0 part of the modified quantum affine algebra $\tilde{U}_q (\widehat{{\frak s}{\frak l}_2})_0$ is given by path. Weyl group actions, extremal vectors and crystal structure of all irreducible components are described explicitly.

We study residues on a complete toric variety $X$, which are defined in terms of the homogeneous coordinate ring of $X$. We first prove a global transformation law for toric residues. When the fan of the toric variety has a simplicial cone of maximal dimension, we can produce an element with toric residue equal to 1. We also show that in certain situations, the toric residue is an isomorphism on an appropriate graded piece of the quotient ring. When $X$ is simplicial, we prove that the toric residue is a sum of local residues. In the case of equal degrees, we also show how to represent $X$ as a quotient $(Y\setminus\{0\})/C\ast$ such that the toric residue becomes the local residue at 0 in $Y$.

In this paper we take up the problem of discussing $C R$ manifolds of arbitrary $C R$ codimension. We closely follow the general method of N. Tanaka, while concentrating our attention to the case of manifolds endowed with partial complex structures. This study required a deeper understanding of the structure of the Levi–Tanaka algebras, which are the canonical prolongation of pseudocomplex fundamental graded Lie algebras. These algebras enjoy special properties, the understanding of which provided also a way to build up several different examples and points to a rich field of investigations. Here we restrained further our consideration to the homogeneous models.

We present some basic identities for hypergeometric functions associated with the integrals of Euler type. We give a geometrical proof for formulae such as the identity between the single and double integrals expressing Appell's hypergeometric series $F_1 (a, b, b^{\prime} c; x, y)$.

This paper generalizes the definition of mixed perverse sheaves to schemes of finite type over a number field. Their basic properties, e.g., characterization of simple objects, are shown.

We prove that the isomorphism class of an affine hyperbolic curve defined over a field finitely generated over ${\bb Q}$ is completely determined by its arithmetic fundamental group. We also prove a similar result for an affine curve defined over a finite field.

This article determines the asymptotic behavior of a class of two variable ‘simultaneous’ lattice point problems in ${\bb R}^n$ for any $n \geqslant 2$. An earlier article [Li-3] has studied a similar problem for a large class of such problems in ${\bb R}^2$.

We study automorphisms of a generic Jacobian Kummer surface. First we analyse the action of classically known automorphisms on the Picard lattice of the surface, then proceed to construct new automorphisms not generated by classical ones. We find 192 such automorphisms, all conjugate by the symmetry group of the (16,6)-configuration.

We express Néron functions and Schneider's local $p$-adic height pairing on an abelian variety $A$ with split multiplicative reduction with theta functions and their automorphy factors on the rigid analytic torus uniformizing $A$. Moreover, we show formulas for the $\rho$-splittings of the Poincaré biextension corresponding to Néron's and Schneider's local height pairings.

The jacobian variety of the Catalan curve $y^q = x^p - 1$ is shown to be nondegenerate. As an application, a 0-1-matrix whose determinant computes the relative class number of the $pq$-th cyclotomic field is constructed.