TGTomasz Grzywny

Tomasz Grzywny

*This is an algorithmically generated author record based on publicly available information.

Current Organizations / Institutes

The organizations/institutes from the scholar's latest article


Tomasz Grzywny has a total of 35 co-authors. Here are the top co-authors by number of shared publications:


Latest Publications

  • Hardy inequalities and nonlocal capacity

    by Tomasz Grzywny, Julia Lenczewska

    In this article, we introduce and study capacities related to nonlocal Sobolev spaces, with focus on spaces corresponding to zero-order nonlocal operators. In particular, we prove Hardy-type inequalities to obtain Sobolev embeddings and use them to estimate the nonlocal capacities of a ball.


  • Partial versus total resetting for Lévy flights in d dimensions: Similarities and discrepancies

    by Costantino Di Bello, Aleksei Chechkin, Tomasz Grzywny, Zbigniew Palmowski, Karol Szczypkowski, Bartosz Trojan

    While stochastic resetting (or total resetting) is a less young and more established concept in stochastic processes, partial stochastic resetting (PSR) is a relatively new field. PSR means that, at random moments in time, a stochastic process gets multiplied by a factor between 0 and 1, thus approaching but not reaching the resetting position. In this paper, we present new results on PSR highlighting the main similarities and discrepancies with total resetting. Specifically, we consider both symmetric α-stable Lévy processes (Lévy flights) and Brownian motion with PSR in arbitrary d dimensions. We derive explicit expressions for the propagator and its stationary measure and discuss in detail their asymptotic behavior. Interestingly, while approaching to stationarity, a dynamical phase transition occurs for the Brownian motion, but not for Lévy flights. We also analyze the behavior of the process around the resetting position and find significant differences between PSR and total resetting.


  • Liouville’s theorems for Lévy operators

    by Tomasz Grzywny, Mateusz Kwaśnicki


  • Open Access

    Stationary states for stable processes with partial resetting

    by Tomasz Grzywny, Karol Szczypkowski, Zbigniew Palmowski, Bartosz Trojan

    We study a $d$-dimensional stochastic process $\mathbf{X}$ which arises from a Lévy process $\mathbf{Y}$ by partial resetting, that is the position of the process $\mathbf{X}$ at a Poisson moment equals $c$ times its position right before the moment, and it develops as $\mathbf{Y}$ between these two consecutive moments, $c \in (0, 1)$. We focus on $\mathbf{Y}$ being a strictly $α$-stable process with $α\in (0,2]$ having a transition density: We analyze properties of the transition density $p$ of the process $\mathbf{X}$. We establish a series representation of $p$. We prove its convergence as time goes to infinity (ergodicity), and we show that the limit $ρ_{\mathbf{Y}}$ (density of the ergodic measure) can be expressed by means of the transition density of the process $\mathbf{Y}$ starting from zero, which results in closed concise formulae for its moments. We show that the process $\mathbf{X}$ reaches a non-equilibrium stationary state. Furthermore, we check that $p$ satisfies the Fokker--Planck equation, and we confirm the harmonicity of $ρ_{\mathbf{Y}}$ with respect to the adjoint generator. In detail, we discuss the following cases: Brownian motion, isotropic and $d$-cylindrical $α$-stable processes for $α\in (0,2)$, and $α$-stable subordinator for $α\in (0,1)$. We find the asymptotic behavior of $p(t;x,y)$ as $t\to +\infty$ while $(t,y)$ stays in a certain space-time region. For Brownian motion, we discover a phase transition, that is a change of the asymptotic behavior of $p(t;0,y)$ with respect to $ρ_{\mathbf{Y}}(y)$.

  • Open Access

    Alexandrov Theorem for nonlocal curvature

    by Wojciech Cygan, Tomasz Grzywny

    In this article we obtain a nonlocal version of the Alexandrov Theorem which asserts that the only set with sufficiently smooth boundary and of constant nonlocal mean curvature is an Euclidean ball. We consider a general nonlocal mean curvature given by a radial and monotone kernel and we formulate an easy-to-check condition which is necessary and sufficient for the nonlocal version of the Alexandrov Theorem to hold in the treated context. Our definition encompasses numerous examples of various nonlocal mean curvatures that have been already studied in the literature. To prove the main result we obtain a specific formula for the tangential derivative of the nonlocal mean curvature and combine it with an application of the method of moving planes.

  • Open Access

    Hardy inequalities and nonlocal capacity

    by Tomasz Grzywny, Julia Lenczewska

    In this article, we introduce and study capacities related to nonlocal Sobolev spaces, with focus on spaces corresponding to zero-order nonlocal operators. In particular, we prove Hardy-type inequalities to obtain Sobolev embeddings and use them to estimate the nonlocal capacities of a ball.

  • Open Access

    Nonlinear nonlocal Douglas identity

    by Krzysztof Bogdan, Tomasz Grzywny, Katarzyna Pietruska-Pałuba, Artur Rutkowski

    We give Hardy–Stein and Douglas identities for nonlinear nonlocal Sobolev–Bregman integral forms with unimodal Lévy measures. We prove that the corresponding Poisson integral defines an extension operator for the Sobolev–Bregman spaces. As an application, we obtain the boundedness of the Dirichlet-to-Neumann operator on weighted $$L^p$$ L p spaces. We also show that the Poisson integrals are quasiminimizers of the Sobolev–Bregman forms.


  • Open Access

    Asymptotics of non-local perimeters

    by Wojciech Cygan, Tomasz Grzywny

    We introduce a notion of non-local perimeter which is defined through an arbitrary positive Borel measure on $${\mathbb {R}}^d$$Rd which integrates the function $$1\wedge |x|$$1∧|x| . Such definition of non-local perimeter encompasses a wide range of perimeters which have been already studied in the literature, including fractional perimeters and anisotropic fractional perimeters. The main part of the article is devoted to the study of the asymptotic behaviour of non-local perimeters. As direct applications we recover well-known convergence results for fractional perimeters and anisotropic fractional perimeters.


  • Open Access

    Asymptotic expansion of the nonlocal heat content

    by Tomasz Grzywny, Julia Lenczewska

    Let $\mathbf{X}=\{X_t\}_{t\geq 0}$ be a L\'evy process in $\mathbb{R}^d$ and $\Omega$ be an open subset of $\mathbb{R}^d$ with finite Lebesgue measure. In this article we consider the quantity $H(t)=\int_{\Omega} \mathbb{P}^x (X_t\in\Omega^c) \, \mathrm{d}x$ which is called the heat content. We study its asymptotic expansion for isotropic $\alpha$-stable L\'evy processes and more general L\'evy processes, under mild assumptions on the characteristic exponent.