No Arabic abstract
Let (X_R, 0) be a germ of real analytic subset in (R^N, 0) of pure dimension n+1 with an isolated singularity at 0. Let (f_R,0) : (X_R, 0) --> (R,0) a real analytic germ with an isolated singularity at 0, such that its complexification f_C vanishes on the singular set S of X_C. We also assume that X_R-[0] is orientable. To each $ A in H^{0}(X_{mathbb{R}} - lbrace 0 rbrace ,mathbb {C}) $ we associate a $n-$cycle $ Gamma(A) $ (explicitly described) in the complex Milnor fiber of $f_{mathbb{C}}$ at 0 such that the non trivial terms in the asymptotic expansions of the oscillating integrals $ int_{A} e^{itau f(x)} phi(x) $ when $ tau to pm infty $ can be read from the spectral decomposition of $Gamma(A) $ relative to the monodromy of $f_{mathbb{C}}$ at 0 .
The aim of this fisrt part is to introduce, for a rather large class of hypersurface singularities with 1 dimensionnal locus, the analog of the Brieskorn lattice at the origin (the singular point of the singular locus). The main results are the finitness theorem for the corresponding (a,b)-module obtained via Kashiwaras constructibility theorem, and non torsion results for a plane curve singularity (not nessarily reduced) and for the suspension of such non torsion cases with an isolated singularity.
In the framework of semiclassical resonances, we make more precise the link between polynomial estimates of the extension of the resolvent and propagation of the singularities through the trapped set. This approach makes it possible to eliminate infinity and to concentrate the study near the trapped set. It has allowed us in previous papers to obtain the asymptotic of resonances in various geometric situations.
We study the local invariants that a meromorphic $k$-differential on a Riemann surface of genus $ggeq0$ can have. These local invariants are the orders of zeros and poles, and the $k$-residues at the poles. We show that for a given pattern of orders of zeroes, there exists, up to a few exceptions, a primitive $k$-differential having these orders of zero. The same is true for meromorphic $k$-differentials and in this case, we describe the tuples of complex numbers that can appear as $k$-residues at their poles. For genus $ggeq2$, it turns out that every expected tuple appears as $k$-residues. On the other hand, some expected tuples are not the $k$-residues of a $k$-differential in some remaining strata. This happens in the quadratic case in genus $1$ and in genus zero for every $k$. We also give consequences of these results in algebraic and flat geometry.
Let G be a connected reductive group defined over Q_p. The set of crystals contained in a given G-isocrystal is viewed from a Bruhat-Tits building-theoretic vantage point as a kind of tubular neighborhood of a skeleton characterized by a minimality property arising from metric space theory.
Two algorithms proposed by Leo Breiman : CART trees (Classification And Regression Trees for) introduced in the first half of the 80s and random forests emerged, meanwhile, in the early 2000s, are the subject of this article. The goal is to provide each of the topics, a presentation, a theoretical guarantee, an example and some variants and extensions. After a preamble, introduction recalls objectives of classification and regression problems before retracing some predecessors of the Random Forests. Then, a section is devoted to CART trees then random forests are presented. Then, a variable selection procedure based on permutation variable importance is proposed. Finally the adaptation of random forests to the Big Data context is sketched.