arXiv subjects

Pilgyu Jung

Publications and source records attributed to Pilgyu Jung.

5 recordsLinked to original sources

arXiv2025

$L_p$-estimates of the conormal derivative problem for parabolic equations with time measurable coefficients and $A_p$-weights

This paper investigates weighted mixed-norm estimates for divergence-type parabolic equations on Reifenberg-flat domains with the conormal derivative boundary condition. The leading coefficients are assumed to be merely measurable in the time variable and to have small mean oscillations in the spatial variables. In deriving the boundary estimates, we overcome a regularity issue by employing half-time derivative estimates.

math.AP↗

arXiv2025

Fabes-Stroock approach to higher integrability of Green's functions and ABP estimates with $L_d$ drift

We explore the higher integrability of Green's functions associated with the second-order elliptic equation $a^{ij}D_{ij}u + b^i D_iu = f$ in a bounded domain $Ω\subset \mathbb{R}^d$, and establish an enhanced version of Aleksandrov's maximum principle. In particular, we consider the drift term $b=(b^1, \ldots, b^d)$ in $L_d$ and the source term $f \in L_p$ for some $p < d$. This provides an alternative and analytic proof of a result by N. V. Krylov (\textit{Ann. Probab.}, 2021) concerning $L_d$ drifts. The key step involves deriving a Gehring-type inequality for Green's functions by using the Fabes-Stroock approach (\textit{Duke Math. J.}, 1984).

math.AP↗

arXiv2025

Network Consensus in the Wasserstein Space of Probability Measures Defined on Multi-Dimensional Euclidean Spaces

The consensus problem -- achieving agreement among a network of agents -- is a central theme in both theory and applications. Recently, this problem has been extended from Euclidean spaces to the space of probability measures, where the natural notion of averaging is given by the Wasserstein barycenter. While prior work established convergence in one dimension, the case of higher dimensions poses additional challenges due to the curved geometry of Wasserstein space. In this paper, we develop a framework for analyzing such consensus algorithms by employing a Wasserstein version of Jensen's inequality. This tool provides convexity-type estimates that allow us to prove convergence of nonlinear consensus dynamics in the Wasserstein space of probability measures on $\mathbb{R}^d$.

math.OC↗

arXiv2024

$L_p$-estimates for parabolic equations in divergence form with a half-time derivative

We establish the unique solvability of solutions in Sobolev spaces to linear parabolic equations in a more general form than those in the literature. A distinguishing feature of our equations is the inclusion of a half-order time derivative term on their right-hand side. We anticipate that such equations will prove useful in various problems involving time evolution terms. Notably, the coefficients of the equations exhibit significant irregularity, being merely measurable with respect to the temporal variable or one spatial variable.

math.AP↗

arXiv2021

Boundedness of non-local operators with spatially dependent coefficients and $L_p$-estimates for non-local equations

We prove the boundedness of the non-local operator \[ \mathcal{L}^a u(x)=\int_{\mathbb{R}^d} \left(u(x+y)-u(x)-χ_α(y)\big(\nabla u(x),y\big)\right) a(x,y)\frac{dy}{|y|^{d+α}} \] from $H_{p,w}^α(\mathbb{R}^d)$ to $L_{p,w}(\mathbb{R}^d)$ for the whole range of $p \in (1,\infty)$, where $w$ is a Muckenhoupt weight. The coefficient $a(x,y)$ is bounded, merely measurable in $y$, and Hölder continuous in $x$ with an arbitrarily small exponent. We extend the previous results by removing the largeness assumption on $p$ as well as considering weighted spaces with Muckenhoupt weights. Using the boundedness result, we prove the unique solvability in $L_p$ spaces of the corresponding parabolic and elliptic non-local equations.

math.AP↗