Let X be a K3 surface over a number field K. We prove that there exists a finite algebraic field extension E/K such that X has ordinary reduction at every non-archimedean place of E outside a density zero set of places.

The goal of this paper is to study certain $p$-adic differential operators on automorphic forms on $U(n,n)$. These operators are a generalization to the higher-dimensional, vector-valued situation of the $p$-adic differential operators constructed for Hilbert modular forms by N. Katz. They are a generalization to the $p$-adic case of the $C^{\infty }$-differential operators first studied by H. Maass and later studied extensively by M. Harris and G. Shimura. The operators should be useful in the construction of certain $p$-adic...

For a variety over a local field, Bloch proposed a conjectural formula for the alternating sum of Artin conductor of $\ell$-adic cohomology. We prove that the formula is valid modulo 2 if the variety has even dimension.

We show that the generalized Fermat equations with signatures (5,5,7), (5,5,19), and (7,7,5) (and unit coefficients) have no non-trivial primitive integer solutions. Assuming GRH, we also prove the non-existence of non-trivial primitive integer solutions for the signatures (5,5,11), (5,5,13), and (7,7,11). The main ingredients for obtaining our results are descent techniques, the method of Chabauty-Coleman, and the modular approach to Diophantine equations.

Soit $E$ une courbe elliptique sur $\mathbb{Q}$ par un modèle de Weierstrass généralisé :$$y^2+A_{1}xy+A_{3}y=x^3+A_2{x}^2+A_{4}x+A_6;A_i\in \mathbb{Z}.$$Soit $M=(a/d^2,b/d_3)$ avec $(a,d)=1$, un point rationnel sur cette courbe. Pour tout entier $m$, on exprime les coordonnées de $mM$ sous la forme :$$mM=\left(\frac{{\phi }_m\left(M\right)}{{\psi }_n^2\left(m\right)},\frac{{\omega }_m\left(M\right)}{{\psi }_m^3\left(M\right)}\right)=\left(\frac{{\widehat{\phi }}_m}{d^2{\widehat{\psi }}_m^2},\frac{{\widehat{\omega }}_m}{d^3{\widehat{\psi }}_m^3}\right),$$où ${\phi }_m,\psi \_m,{\omega }_m\in \mathbb{Z}[A_1,\cdots ,A_6,x,y]$ et ${\widehat{\phi }}_m$, ${\widehat{\psi }}_m$, ${\widehat{\omega }}_m$ sont déduits par multiplication par des puissances convenables de $d$.Soit $p$ un nombre premier impair et supposons que $M\left(\mathrm{mod}p\right)$ est non singulier et que le rang d’apparition de $p$ dans la suite d’entiers $\left({\widehat{\psi }}_m\right)$ est supérieur ou égal à trois. Notons ce rang par $r=r\left(p\right)$ et soit ${\nu }_p({\widehat{\psi }}_r)=e_0\ge 1$. Nous montrons que la suite $\left({\widehat{\psi }}_m\right)$...