On établit quelques résultats généraux relatifs à la taille du groupe d’automorphismes de l’espace de Douady de points sur une surface, puis on étudie quelques propriétés des automorphismes provenant d’un automorphisme de la surface, en particulier leur action sur la cohomologie et la classification de leurs points fixes.

We consider the problem of minimizing the energy of $N$ points repelling each other on curves in ${{\mathbb{R}}^{d}}$ with the potential ${{\left| x\,-\,y \right|}^{-s}},\,s\,\ge \,1$, where $\left| \cdot \right|$ is the Euclidean norm. For a sufficiently smooth, simple, closed, regular curve, we find the next order term in the asymptotics of the minimal s-energy. On our way, we also prove that at least for $s\,\ge \,2$, the minimal pairwise distance in optimal configurations asymptotically equals $L/N,\,N\to \,\infty $, where $L$ is the length of the curve.

We consider the Randers space $({{V}^{n}},\,{{F}_{b}})$ obtained by perturbing the Euclidean metric by a translation, ${{F}_{b}}\,=\,\alpha \,+\,\beta $, where $\alpha $ is the Euclidean metric and $\beta $ is a 1-form with norm $b,\,0\,\le \,b\,<\,1$. We introduce the concept of a hypersurface with constant mean curvature in the direction of a unitary normal vector field. We obtain the ordinary differential equation that characterizes the rotational surfaces $({{V}^{3}},\,{{F}_{b}})$ of constant mean curvature (cmc) in the direction of a unitary normal vector field. These equations reduce to the classical equation of the rotational cmc surfaces in Euclidean space, when $b\,=\,0$. It also reduces to the equation that characterizes the minimal rotational surfaces in $({{V}^{3}},\,{{F}_{b}})$ when $H\,=\,0$, obtained by M. Souza and K. Tenenblat. Although the differential equation depends on the choice of the normal direction, we show that both equations determine the same rotational surface, up to a reflection. We also show that the round cylinders are cmc surfaces in the direction of the unitary normal field. They are generated by the constant solution of the differential equation. By considering the equation as a nonlinear dynamical system, we provide a qualitative analysis, for $0\,<\,b\,<\,\frac{\sqrt{3}}{3}$. Using the concept of stability and considering the linearization around the single equilibrium point (the constant solution), we verify that the solutions are locally asymptotically stable spirals. This is proved by constructing a Lyapunov function for the dynamical systemand by determining the basin of stability of the equilibrium point. The surfaces of rotation generated by such solutions tend asymptotically to one end of the cylinder.

Let $E$ be an elliptic curve over $\mathbb{Q}$ without complex multiplication, and for each prime $p$ of good reduction, let ${{n}_{E}}(p)\,=\,\left| E\left( {{\mathbb{F}}_{p}} \right) \right|$. For any integer $b$, we consider elliptic pseudoprimes to the base $b$. More precisely, let ${{Q}_{E,B}}(x)$ be the number of primes $p\le x$ such that ${{b}^{{{n}_{E}}(p)}}\,\equiv \,b\left( \bmod \,{{n}_{E}}\left( p \right) \right)$, and let $\pi _{E,b}^{\text{pseu}}(x)$ be the number of compositive${{n}_{E}}(p)$ such that ${{b}^{{{n}_{E}}(p)}}\,\equiv \,b\left( \bmod \,{{n}_{E}}\left( p \right) \right)$ (also called elliptic curve pseudoprimes). Motivated by cryptography applications, we address the problem of finding upper bounds for ${{Q}_{E,B}}(x)$ and $\pi _{E,b}^{\text{pseu}}(x)$, generalising some of the literature for the classical pseudoprimes to this new setting.

We introduce a flow of a spatial graph and see how invariants for spatial graphs and handlebody-links are derived from those for flowed spatial graphs. We define a new quandle (co)homology by introducing a subcomplex of the rack chain complex. Then we define quandle colorings and quandle cocycle invariants for spatial graphs and handlebody-links.

In this article, we study the correspondence between the geometry of del Pezzo surfaces ${{s}_{r}}$ and the geometry of the $r$-dimensional Gosset polytopes (${{(r-4)}_{21}}$. We construct Gosset polytopes ${{(r-4)}_{21}}$ in Pic ${{S}_{r}}\,\otimes \,\mathbb{Q}$ whose vertices are lines, and we identify divisor classes in Pic ${{s}_{r}}$ corresponding to $(a-1)$-simplexes $(a\le r)$, $(r-1)$-simplexes and $(r-1)$-crosspolytopes of the polytope ${{(r-4)}_{21}}$. Then we explain how these classes correspond to skew $a$-lines$(a\le r)$, exceptional systems, and rulings, respectively.

As an application, we work on the monoidal transform for lines to study the local geometry of the polytope ${{(r-4)}_{21}}$. And we show that the Gieser transformation and the Bertini transformation induce a symmetry of polytopes ${{3}_{21}}$ and ${{4}_{21}}$, respectively.

Fix an elliptic curve $E/\mathbf{Q}$and assume the Riemann Hypothesis for the $L$-function $L({{E}_{D}},\,s)$ for every quadratic twist ${{E}_{D}}$ of $E$ by $D\,\in \,\mathbf{Z}$. We combine Weil's explicit formula with techniques of Heath-Brown to derive an asymptotic upper bound for the weighted moments of the analytic rank of ${{E}_{D}}$. We derive from this an upper bound for the density of low-lying zeros of $L({{E}_{D}},\,s)$ that is compatible with the randommatrixmodels of Katz and Sarnak. We also show that for any unbounded increasing function $f$ on $\mathbf{R}$, the analytic rank and (assuming in addition the Birch and Swinnerton-Dyer conjecture) the number of integral points of ${{E}_{D}}$ are less than $f(D)$ for almost all $D$.

We study negative powers of Laguerre differential operators in ${{\mathbb{R}}^{d}},\,d\,\ge \,1$. For these operators we prove two-weight $[{{L}^{p}}\,-\,{{L}^{q}}$ estimates with ranges of $q$ depending on $p$. The case of the harmonic oscillator (Hermite operator) has recently been treated by Bongioanni and Torrea by using a straightforward approach of kernel estimates. Here these results are applied in certain Laguerre settings. The procedure is fairly direct for Laguerre function expansions of Hermite type, due to some monotonicity properties of the kernels involved. The case of Laguerre function expansions of convolution type is less straightforward. For half-integer type indices. we transfer the desired results from the Hermite setting and then apply an interpolation argument based on a device we call the convexity principle to cover the continuous range of $\alpha \,\in \,\,{{[-1/2,\infty )}^{d}}$. Finally, we investigate negative powers of the Dunkl harmonic oscillator in the context of a finite reflection group acting on ${{\mathbb{R}}^{d}}$ and isomorphic to $\mathbb{Z}_{2}^{d}$. The two weight ${{L}^{p}}\,-\,{{L}^{q}}$ estimates we obtain in this setting are essentially consequences of those for Laguerre function expansions of convolution type.

In this paper, we establish the regularity of strong solutions to nondivergence parabolic equations with BMO coefficients in nondoubling weighted spaces.