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Published in: Annales Mathématiques Blaise Pascal, 24(2) (2017), 235--291.; Let k be a totally real number field ant let k∞ be its cyclotomic Zp-extension for a prime p>2. We give (Theorem 3.2) a sufficient condition of nullity of the Iwasawa invariants lambda, mu, when p totally splits in k, and we obtain important tables of quadratic fields and p for which we can conclude that lambda = mu=0.We show that the number of ambiguous p-classes of kn (nth stage in k∞) is equal to the order of the torsion group T, of the Galois group of the maximal Abelian p-ramified pro-p-extension of k (Theorem 4.2), for all n >> e, where p^e is the exponent of U*/ adh(E) (in terms of local and global units of k). Then we establish analogs of Chevalley's formula using a family (Lambda_i^n)_{0≤i≤m_n} of subgroups of k* containing E, in which any x is norm of an ideal of kn. This family is attached to the classical filtration of the p-class group of kn defining the algorithm of computation of its order in m_n steps. From this, we prove (Theorem 6.1) that m_n ≥ (lambda.n + mu.p^n + nu)/v_p(T_k) and that the condition m_n = O(1) (i.e., lambda = mu=0) essentially depends on the P-adic valuations of the (x^(p-1)-1)/p, x in Lambda_i^n, for P I p, so that Greenberg's conjecture is strongly related to ``Fermat quotients'' in k*. Heuristics and statistical analysis of these Fermat quotients (Sections 6, 7, 8) show that they follow natural probabilities, linked to T_k whatever n, suggesting that lambda = mu=0 (Heuristics 7.1, 7.2, 7.3). This would imply that, for a proof of Greenberg's conjecture, some deep p-adic results (probably out of reach now), having some analogy with Leopoldt's conjecture, are necessary before referring to the sole algebraic Iwasawa theory.

Dans cet article, nous nous intéressons aux dimensions de certaines variétés qui ont été introduites récemment par Kisin pour démontrer la modularité de certaines représentations galoisiennes. Nous étudions plus spécialement un cas particulier pour lequel nous donnons une estimation de la dimension en question, puis, en nous basant sur ce résultat, nous énonçons une conjecture dans le cas général. In this paper, we study dimensions of some varieties, that were introduced recently by Kisin in order to prove modularity of some Galois representations. In fact, we mainly consider a special case for which we obtain an estimation of the dimension we are interested in. Then, based on this result, we state a conjecture for the general case.

On R d , we consider the differential operator −�+jj xjj 2 +R(x)+M. Here R is in the Schwartz class and M is a bounded operator of L 2 (R). Under a localization hypothesis on the spectrum of −� + jj xjj 2 + R(x), which is automatically satisfied if d = 1, one proves that there are arbitrarily small operator M, i.e. jj M jj � 1, such that for all r � 3, for small Cauchy data of order " in high Sobolev norms, the nonlinear Schrodinger equation admits a solution which is bounded by 2" on a time existence interval of length � " −r . The case R = 0 has been proved by Grebert-Imekraz-Paturel. Here we do not need any explicit spectral analysis (eigenvalues and eigenfunctions) of −� + jj xjj 2 + R(x). The role of M is making the spectrum of −�+ jj xjj 2 + R(x)+ M nonresonant. We also give a partial answer in the case M = 0 : there are some potentials R such that the spectrum of −@2 x + x2 + R(x) is nonresonant. For this, we use some Chelkak-Kargaev-Korotyaev's results about the inverse spectral problem of harmonic oscillator and construct explicit dual basis of the squared Hermite functions. Sur R d , nous considerons l'operateur differentiel −� + jj xjj 2 + R(x) +

The structure of anticyclic operad on the Dendriform operad defines in particular a matrix of finite order acting on the vector space spanned by planar binary trees. We compute its characteristic polynomial and propose a (compatible) conjecture for the characteristic polynomial of the Coxeter transformation for the Tamari lattice, which is mostly a square root of this matrix., Comment: 12 pages

This article completes the results of our previous paper [B.91] on interaction of consecutive strata for the vanishing cycles. In the same context that loc. cit., we treat here the tangling phenomenon for a given cohomology class of the Milnor’s fiber of f at the origin in the case where its nilpotency order for the given eigenvalue e −2iπ.u � of the monodromy is not necessarily bigger or equal than the nilpotency order of the monodromy for this eigenvalue at the generic point of the big stratum. We show that this tangling phenomenon can always be detected on the poles of the meromorphic extension of the distribution R X |f | 2λ ˜.

We explain how it is possible to obtain the necessary conditions on functions defining a germ of planar web in order that it be of maximal rank. Then we apply this method to the study of maximal rank 5-webs. We show the existence of many exceptional 5-webs non-equivalent to Bol's web, thus giving an answer to Chern's problem. To cite this article: L. Pirio, C. R. Acad. Sci. Paris, Ser. I 339 (2004).

RésuméOn the set of minimax trees of a given order there can be defined two families of operations, the complements and the reverses. We study the actions of those operations and show that their orbits are enumerated by combinatorial objects previously introduced, such as the Hetyei–Reiner trees, the increasing trees, and the André trees. Various generating functions for those trees by several statistics are also derived.