Emmanuel Russ

  1. A note on precised Hardy inequalities on Carnot groups and Riemannian manifolds.

    Authors: Yannick Sire, Emmanuel Russ
    Subjects: Functional Analysis
    Abstract

    We prove non local Hardy inequalities on Carnot groups and Riemannian
    manifolds, relying on integral representations of fractional Sobolev norms.

  2. Non local Poincar\'e inequalities on Lie groups with polynomial volume growth.

    Authors: Yannick Sire, Emmanuel Russ
    Subjects: Functional Analysis
    Abstract

    Let $G$ be a real connected Lie group with polynomial volume growth, endowed
    with its Haar measure $dx$. Given a $C^2$ positive function $M$ on $G$, we give
    a sufficient condition for an $L^2$ Poincar\'e inequality with respect to the
    measure $M(x)dx$ to hold on $G$. We then establish a non-local Poincar\'e
    inequality on $G$ with respect to $M(x)dx$.

  3. Fractional Poincar\'e inequalities for general measures.

    Authors: Clément Mouhot, Yannick Sire, Emmanuel Russ
    Subjects: Analysis of PDEs
    Abstract

    We prove a fractional version of Poincar\'e inequalities in the context of
    $\R^n$ endowed with a fairly general measure. Namely we prove a control of an
    $L^2$ norm by a non local quantity, which plays the role of the gradient in the
    standard Poincar\'e inequality. The assumption on the measure is the fact that
    it satisfies the classical Poincar\'e inequality, so that our result is an
    improvement of the latter inequality. Moreover we also quantify the tightness
    at infinity provided by the control on the fractional derivative in terms of a
    weight growing at infinity.

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