Hopf algebras and Markov chains: Two examples and a theory

The operation of squaring (coproduct followed by product) in a combinatorial Hopf algebra is shown to induce a Markov chain in natural bases. Chains constructed in this way include widely studied methods of card shuffling, a natural "rock-breaking" process, and Markov chains on simplicial complexes. Many of these chains can be explictly diagonalized using the primitive elements of the algebra and the combinatorics of the free Lie algebra. For card shuffling, this gives an explicit description of the eigenvectors. For rock-breaking, an explicit description of the quasi-stationary distribution and sharp rates to absorption follow.Comment: 51 pages, 17 figures. (Typographical errors corrected. Further fixes will only appear on the version on Amy Pang's website, the arXiv version will not be updated.

Moments, cumulants and diagram formulae for non-linear functionals of random measures

This survey provides a unified discussion of multiple integrals, moments, cumulants and diagram formulae associated with functionals of completely random measures. Our approach is combinatorial, as it is based on the algebraic formalism of partition lattices and M\"obius functions. Gaussian and Poisson measures are treated in great detail. We also present several combinatorial interpretations of some recent CLTs involving sequences of random variables belonging to a fixed Wiener chaos.Comment: Survey, preliminary draft. 104 pages. 30 Figure

Mixed Eulerian numbers and Peterson Schubert calculus

In this paper we derive a combinatorial formula for mixed Eulerian numbers in type $A$ from Peterson Schubert calculus. We also provide a simple computation for mixed $\Phi$-Eulerian numbers in arbitrary Lie types.Comment: 37 page

Coalescent tree based functional representations for some Feynman-Kac particle models

We design a theoretic tree-based functional representation of a class of Feynman-Kac particle distributions, including an extension of the Wick product formula to interacting particle systems. These weak expansions rely on an original combinatorial, and permutation group analysis of a special class of forests. They provide refined non asymptotic propagation of chaos type properties, as well as sharp \LL\_p-mean error bounds, and laws of large numbers for $U$-statistics. Applications to particle interpretations of the top eigenvalues, and the ground states of Schr\"{o}dinger semigroups are also discussed

Invariance principles for homogeneous sums: Universality of Gaussian Wiener chaos

We compute explicit bounds in the normal and chi-square approximations of multilinear homogenous sums (of arbitrary order) of general centered independent random variables with unit variance. In particular, we show that chaotic random variables enjoy the following form of universality: (a) the normal and chi-square approximations of any homogenous sum can be completely characterized and assessed by first switching to its Wiener chaos counterpart, and (b) the simple upper bounds and convergence criteria available on the Wiener chaos extend almost verbatim to the class of homogeneous sums.Comment: Published in at http://dx.doi.org/10.1214/10-AOP531 the Annals of Probability (http://www.imstat.org/aop/) by the Institute of Mathematical Statistics (http://www.imstat.org

Formules d'Itô pour l'équation de la chaleur stochastique à travers les théories des chemins rugueux et des structures de régularité

In this thesis, we develop a general theory to prove the existence of several Itô formulae on the one-dimensional stochastic heat equation driven by additive space-time white noise. That is denoting by u the solution of this SPDE for any smooth enough function f we define some new notions of stochastic integrals defined upon u, which cannot be defined classically, to deduce new identities involving f(u) and some non-trivial corrections. These new relations are obtained by using the theory of regularity structures and the theory of rough paths. In the first chapter, we obtain a differential and an integral identity involving the reconstruction of some modelled distributions. Then we discuss a general change of variable formula over any Hölder continuous path in the context of rough paths, relating it to the notion of quasi-shuffle algebras and the family of so-called quasi-geometric rough paths. Finally, we apply the general results on quasi-geometric rough paths to the time evolution of u. Using the Gaussian behaviour of the process $u$, most of the terms involved in these equations are also identified with some classical constructions of stochastic calculus.Dans cette thèse nous développons une théorie générale pour prouver l'existence de plusieurs formules de Itô sur l'équation de chaleur stochastique unidimensionnelle dirigée par un bruit blanc en espace-temps. Cela revient a définir de nouvelles notions d'intégrales stochastique sur u, la solution de cette EDPS et à obtenir pour toute fonction assez lisse f des nouvelles identités impliquant f(u) et des termes de correction non triviaux. Ces nouvelles relations sont obtenues en utilisant la théorie des structures de régularité et la théorie des chemins rugueux. Dans le premier chapitre nous obtenons une identité intégrale et une différentielle impliquant la reconstruction de certaines distributions modélisées. Ensuite, nous discutons d'une formule générale de changement de variable pour tout chemins Hölderiens dans le contexte des chemins rugueux en le rapportant à la notion d'algèbres quasi-shuffle et à la famille des chemins rugueux dits quasi-géométriques. Enfin nous appliquons les résultats généraux sur les chemins rugueux quasi-géométriques à l'évolution temporelle du processus u. En utilisant le comportement gaussien de u, nous identifions la plupart des termes impliqués dans ces équations avec certaines constructions du calcul stochastique