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 workshop2025
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BEGIN:VEVENT
UID:chen@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Main University Building (UHG), Lecture Hall H16
STATUS:CONFIRMED
SUMMARY:Talk of Zhen-Qing Chen
DESCRIPTION:Zhen-Qing Chen (Seattle)\n\n
 Title. Uniform boundary Harnack principle for non-local operators\n\n
 Abstract.
  Boundary Harnack principle (BHP) is a fundamental principle both in
 Probability and in Analysis. When it holds\, it has many far-reaching
 implications. In this talk\, I will present our recent advances in the
 study of BHP that establishes a uniform BHP on any open sets for a
 large class of jump diffusions (or equivalently\, non-local operators)
 under a jump measure comparability and tail estimate condition\, and
 an upper bound condition on the distribution functions for the exit
 times from balls. These conditions are satisfied by a large class of
 non-local operators\,  including those that admit a two-sided mixed
 stable-like heat kernel bound when  the underlying metric measure
 spaces have  volume doubling and reverse volume doubling properties.
 The results of this paper are new even for non-local operators on
 Euclidean spaces. In particular\, our results give not only the scale
 invariant but also uniform BHP for the first time for non-local
 operators on Euclidean spaces  of both divergence form and    
 non-divergence form  with measurable coefficients.    Based on joint
 work with Shiping Cao.
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250217T091500
DTEND;TZID=Europe/Berlin:20250217T095500
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:leeyw@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Main University Building (UHG), Lecture Hall H16
STATUS:CONFIRMED
SUMMARY:Talk of Yongwoo Lee
DESCRIPTION:Yong-Woo Lee (SNU)\n\n
 Title. The probability of almost all eigenvalues being real for the
 elliptic real Ginibre ensemble\n\n
 Abstract.
  The elliptic Ginibre orthogonal ensemble (eGinOE) is a one-parameter
 family of random matrix models that interpolates between Hermitian and
 non-Hermitian real random matrix ensembles. A notable feature of this
 model is that its spectrum contains real eigenvalues with non-trivial
 probability. In this talk\, we investigate the large deviation
 probabilities associated with the number of real eigenvalues in the
 eGinOE. We present a precise estimation for the probability that the
 spectrum of the eGinOE consists of all real eigenvalues except for
 finitely many at the strong and weak non-Hermiticity.  This talk is
 based on joint work with Gernot Akemann and Sung-Soo Byun.
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250217T100000
DTEND;TZID=Europe/Berlin:20250217T102500
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:gusakova@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Main University Building (UHG), Lecture Hall H16
STATUS:CONFIRMED
SUMMARY:Talk of Anna Gusakova
DESCRIPTION:Anna Gusakova (Münster)\n\n
 Title. Concentration inequalities for Poisson $U$-statistics\n\n
 Abstract.
  Let $\eta$ be a Poisson point process on a general measurable space. A
 Poisson functional is a random variable $F(\eta)$\, such that almost
 surely we have $F(\eta)=f(\eta)$ for some measurable veal valued
 function $f$ on the space of counting measures. Poisson functionals
 have been intensively studied within last years and they play an
 important role in stochastic geometry since many important geometric
 functionals of stochastic geometry models are in fact Poisson
 functionals. Poisson $U$-statistic is an example of Poisson
 functional\, which has particularly nice structure. In this talk we
 present concentration inequalities for Poisson $U$-statistics under
 some rather mild conditions. We will discuss their optimality and
 consider a few applications to stochastic geometry models.
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250217T110000
DTEND;TZID=Europe/Berlin:20250217T112500
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:leehs@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Main University Building (UHG), Lecture Hall H16
STATUS:CONFIRMED
SUMMARY:Talk of Ho-Sik Lee
DESCRIPTION:Ho-Sik Lee (Bielefeld)\n\n
 Title. Global estimates for elliptic equations with degenerate
 weights\n\n
 Abstract.
  In second-order elliptic equations\, the matrix-valued coefficients
 equipped in equations are usually assumed to be uniformly elliptic.
 One of the generalizations of such an assumption is considering
 Muckenhoupt weight. Assuming the sharp conditions for the coefficient
 as well as for the boundary of the domain\, we obtained the global
 Calderon-Zygmund estimates for the corresponding Dirichlet problem.
 Next\, we consider the mixed boundary value problem\, allowing the
 case that the Dirichlet condition is assumed on the Cantor set of the
 boundary\, and the Neumann condition is assumed on the complement of
 the boundary. Under the certain density condition for the subset where
 the Dirichlet condition is assumed in the sense of capacity\, we
 obtained the existence and higher integrability result. We are also
 planning to consider the mixed exterior value problem for the
 fractional Laplace.  These are joint works with Anna Kh. Balci
 (Charles Univ. in Prague)\, Sun-Sig Byun (SNU)\, Lars Diening
 (Bielefeld)\, and Guy Foghem (Dresden).
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250217T113000
DTEND;TZID=Europe/Berlin:20250217T115000
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:kimkb@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Main University Building (UHG), Lecture Hall H16
STATUS:CONFIRMED
SUMMARY:Talk of Kyeongbae Kim
DESCRIPTION:Kyeongbae Kim (SNU)\n\n
 Title. Gradient estimates for nonlinear nonlocal equations\n\n
 Abstract.
  We discuss potential estimates of non-homogeneous nonlinear nonlocal
 equations. We first recall previously known results about pointwise
 gradient estimates for solutions to the nonlinear generalization of
 Poisson’s equation. Then\, we present pointwise gradient estimates
 of nonlinear nonlocal equations via linear Riesz potentials.  The talk
 is based on a joint work with Lars Diening\, Ho-Sik Lee\, and Simon
 Nowak.
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250217T120000
DTEND;TZID=Europe/Berlin:20250217T122500
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:trutnau@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Main University Building (UHG), Lecture Hall H16
STATUS:CONFIRMED
SUMMARY:Talk of Gerald Trutnau
DESCRIPTION:Gerald Trutnau (SNU)\n\n
 Title. Pointwise and a.e. well-posedness results for degenerate
 Itô-SDEs with measurable coefficients\n\n
 Abstract.
  We present different kinds of existence and uniqueness in law results
 for degenerate Itô stochastic differential equations on Euclidean
 space with measurable coefficients. In a first step\, we develop
 results with respect to almost every starting point of the state space
 and a given (sub-)invariant measure. For this we use functional
 analytic tools together with probabilistic techniques. In a second
 step\, building on the previous results\, we additionally use elliptic
 regularity results for PDEs to consider a pointwise analysis for every
 starting point. If time permits\, we will consider applications.  This
 is joint work with Haesung Lee (Kumoh National Institute of
 Technology\, South Korea).
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250217T140000
DTEND;TZID=Europe/Berlin:20250217T144000
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:rehmeier@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Main University Building (UHG), Lecture Hall H16
STATUS:CONFIRMED
SUMMARY:Talk of Marco Rehmeier
DESCRIPTION:Marco Rehmeier (TU Berlin)\n\n
 Title. $p$-Brownian motion and the $p$-Laplacian\n\n
 Abstract.
  We construct a stochastic process which is related to the fundamental
 solution of the parabolic p-Laplace equation in the same way as
 Brownian motion is related to the heat kernel of the heat equation.
 More precisely\, for the p-Laplace equation we identify an associated
 McKean—Vlasov SDE\, and our constructed stochastic process consists
 of solutions to this SDE and\, moreover\, constitutes a nonlinear
 Markov process. We call this process a p-Brownian\, which for $p=2$
 coincides with standard Brownian motion.  Joint work with Viorel Barbu
 (A.I. Cuza University) and Michael Röckner (Bielefeld University).
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250217T144500
DTEND;TZID=Europe/Berlin:20250217T151000
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:leesw@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Main University Building (UHG), Lecture Hall H16
STATUS:CONFIRMED
SUMMARY:Talk of Seungwoo Lee
DESCRIPTION:Seungwoo Lee (SNU)\n\n
 Title. Mixing of underdamped Langevin dynamics: from cut-off to
 Erying–Kramers formula\n\n
 Abstract.
  The underdamped Langevin dynamics is a stochastic model describing
 evolution of thermostated molecular dynamics. In this talk\, we
 discuss mixing behavior of the underdamped Langevin dynamics in the
 low temperature regime. We observe the cut-off phenonmenon when there
 is only one stable equilibrium\, while observe the metastability when
 there are multiple stable equilibria. We explain quantitatively
 precise analyses for both cases\; the main difficulty of the model is
 the degeneracy of the generator associated with the underdamped
 Langevin dynamics.  This talk is based on two joint works with
 Professor Seo Insuk from Seoul National University and Ramil Mouad
 from INRIA france.
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250217T154500
DTEND;TZID=Europe/Berlin:20250217T161000
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:beznea@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Main University Building (UHG), Lecture Hall H16
STATUS:CONFIRMED
SUMMARY:Talk of Lucian Beznea
DESCRIPTION:Lucian Beznea (Bucharest)\n\n
 Title. Strong Feller semigroups and Markov processes\n\n
 Abstract.
  Our aim is to show  that the strong Feller and the joint (space-time)
 continuity for a semigroup of Markov kernels on a Polish space are not
 enough to ensure the existence of an associated càdlàg Markov
 process on the same space. One simple counterexample is the Brownian
 semigroup on R restricted to R \ {0}\, for which it is shown that
 there is no associated càdlàg Markov process. Using results from
 potential theory we then prove that the analogous result with càdlàg
 Markov process replaced by right Markov process also holds.  The talk
 is based on a joint work with Iulian Cîmpean (Bucharest) and Michael
 Röckner (Bielefeld).
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250217T161500
DTEND;TZID=Europe/Berlin:20250217T165500
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:fyodorov@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Main University Building (UHG), Lecture Hall H16
STATUS:CONFIRMED
SUMMARY:Talk of Yan Fyodorov
DESCRIPTION:Yan Fyodorov (King's College London, Bielefeld)\n\n
 Title. Superposition of plane waves in high spatial dimensions: from
 landscape complexity to the ground state value\n\n
 Abstract.
  I will discuss some statistical properties of a class of models of
 high-dimensional random landscapes defined in a Euclidean space of
 large dimension $N >>1$  via a superposition of $M$ plane waves whose
 amplitudes\, directions of the wavevectors\, and phases are taken to
 be random. The main efforts are directed towards deriving\, and then
 analysing for $N\to \infty\, M\to \infty$ while keeping $\alpha=M/N$
 finite\,  (i)  the rates of asymptotic exponential growth with $N$ of
 the mean number of all critical points and of local minima known as
 the annealed complexities and  (ii)  the expression for the mean (also
 expected to be typical) value of the deepest landscape minimum (the
 ground-state energy).  In particular\, for the latter we derive the
 Parisi-like optimization functional and analyze conditions for the
 optimizer to reflect various phases:  replica-symmetric\, one-step and
 full replica symmetry broken\, as well as criteria for the
 continuous\,  Gardner and random first order transitions between those
 phases.  The talk will be based on the joint work with Bertrand
 Lacroix-A-Chez-Toine\, arXiv:2411.09687
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250218T090000
DTEND;TZID=Europe/Berlin:20250218T094000
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:byun@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Main University Building (UHG), Lecture Hall H16
STATUS:CONFIRMED
SUMMARY:Talk of Sungsoo Byun
DESCRIPTION:Sungsoo Byun (SNU)\n\n
 Title. Spectral moments and Harer–Zagier type recursion formulas in
 random matrix theory\n\n
 Abstract.
  Random matrix theory enjoys an intimate connection with various
 branches of mathematics. One prominent illustration of this
 relationship is the Harer–Zagier formula for spectral moments\,
 which serves as a well-known example demonstrating the combinatorial
 and topological significance inherent in random matrix statistics.
 While the Harer–Zagier formula originates from the study of the
 moduli space of curves\, it also gives rise to a fundamental formula
 in the study of spectral moments of classical random matrices. In this
 talk\, I will introduce Harer–Zagier type formulas for classical
 Hermitian Gaussian random matrix ensembles and present recent progress
 across various models.
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250218T094500
DTEND;TZID=Europe/Berlin:20250218T102500
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:jalowy@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Main University Building (UHG), Lecture Hall H16
STATUS:CONFIRMED
SUMMARY:Talk of Jonas Jalowy
DESCRIPTION:Jonas Jalowy (Münster)\n\n
 Title. Zeros of Polynomials: Limiting distributions, role of the
 coefficients and evolutions under differential flows\n\n
 Abstract.
  Everyone learns how to find the zeros of a quadratic polynomial in
 school\, but for a large n-degree polynomial\, this remains a
 challenging task. This talk explores the limiting zero distribution of
 polynomials as n grows and its connection to their coefficients\,
 focusing on real-rooted and random polynomials.  We begin with a
 user-friendly approach to determine the limiting zero distribution via
 the 'exponential profile' of the coefficients and apply it to various
 classical polynomials and operations such as the Hadamard product\,
 repeated differentiation\, heat flow\, and finite free convolutions. 
 For random polynomials with i.i.d. rescaled coefficients\, the zeros
 are complex\, and their evolution under such differential operators
 becomes more intricate and visualizing. In one prominent example of
 Weyl polynomials undergoing the heat flow\, the limiting zero
 distribution evolves from the circular law into the elliptic law until
 it collapses to the Wigner semicircle law. More generally\, we
 describe the limiting zero distribution and root dynamics from various
 points of view such as (optimal) transport\, differential equations\,
 and free probability.  Illustrative simulations will accompany the
 talk\, leading to intriguing open questions. This talk is based on
 joint works with Brian Hall\, Ching-Wei Ho\, Antonia Höfert\, Zakhar
 Kabluchko\, and Alexander Marynych.
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250218T110000
DTEND;TZID=Europe/Berlin:20250218T112500
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:parkj@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Main University Building (UHG), Lecture Hall H16
STATUS:CONFIRMED
SUMMARY:Talk of Jongil Park
DESCRIPTION:Jongil Park (SNU)\n\n
 Title. A study on rational homology projective planes\n\n
 Abstract.
  A normal projective surface with the same Betti numbers of the
 projective plane $\mathbb{CP}^2$ is called a rational homology
 projective plane or a $\mathbb{Q}$-homology $\mathbb{CP}^2$. People
 working in algebraic geometry and topology have long studied a
 $\mathbb{Q}$-homology $\mathbb{CP}^2$ with possibly quotient
 singularities. It is now known that it has at most five such singular
 points\, but it is still mysterious so that there are many unsolved
 problems left.  In this talk\, I’ll review some known results and
 open problems in this field which might be solved and might not be
 solved in near future. In particular\, I’d like to review the
 following two topics and to report some recent progress:  1. Algebraic
 Montgomery-Yang problem.  2. Classification of $\mathbb{Q}$-homology
 $\mathbb{CP}^2$ with quotient singularities.  This is a joint work
 with Woohyeok Jo and Kyungbae Park.
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250218T113000
DTEND;TZID=Europe/Berlin:20250218T123000
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:kimp@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Center for Interdisciplinary Research (ZiF)
STATUS:CONFIRMED
SUMMARY:Talk of Panki Kim
DESCRIPTION:Panki Kim (SNU)\n\n
 Title. Stability of Hölder regularity and weighted functional
 inequalities\n\n
 Abstract.
  In this talk\, we first introduce new forms of tails of jumping
 measures and weighted functional inequalities for general symmetric 
 Dirichlet forms  on metric measure spaces under general volume
 doubling condition. Our framework covers  Dirichlet forms with
 singular  jumping measures including ones  corresponding to trace
 processes. Using the new weighted functional inequalities\, we
 establish stable equivalent characterizations of  Hölder regularity 
 of parabolic functions for symmetric  Dirichlet forms. As consequences
 of the main result\, we can show Hölder-continuity of  parabolic
 functions for a large class of symmetric Markov processes blowing up
 to infinity at the boundary of state spaces.    This talk  is mainly
 based on a joint work with Soobin Cho (University of Illinois\, USA).
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250219T090000
DTEND;TZID=Europe/Berlin:20250219T094000
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:vondracek@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Center for Interdisciplinary Research (ZiF)
STATUS:CONFIRMED
SUMMARY:Talk of Zoran Vondraček
DESCRIPTION:Zoran Vondraček (Zagreb)\n\n
 Title. Markov processes with jump kernels decaying at the boundary\n\n
 Abstract.
  In this talk I will explain some aspects of a general theory for
 non-local singular operators of the type $$
 	L^{\mathcal{B}}_{\alpha}f(x)=\lim_{\epsilon\to 0} \int_{D\,\\,
 |y-x|>\epsilon}\big(f(y)-f(x)\big) 
 	\mathcal{B}(x\,y)|x-y|^{-d-\alpha}\\,dy\, $$ and $$ 	L
 f(x)=L^{\mathcal{B}}_{\alpha}f(x) - \kappa(x) f(x)\,	 $$ in case $D$
 is  a $C^{1\,1}$ open set in $\mathbb{R}^d$\, $d\ge 2$. The function
 $\mathcal{B}(x\,y)$ above may vanish at the boundary of $D$\, and the
 killing potential $\kappa$  may be subcritical or critical.  From a
 probabilistic point of view we study the reflected process on the
 closure $\overline{D}$ with infinitesimal generator
 $L^{\mathcal{B}}_{\alpha}$\, and its part process on $D$ obtained by
 either killing at the boundary $\partial D$\, or by killing via the
 killing potential $\kappa(x)$. The general theory developed in this
 work (i)  contains  subordinate killed stable processes in $C^{1\,1}$
 open sets as a special case\, (ii) covers the case when
 $\mathcal{B}(x\,y)$ is bounded between two positive constants and is
 well approximated by certain Hölder continuous functions\, and (iii)
 extends the main results known for the half-space in $\mathbb{R}^d$.
 The main results are the boundary Harnack principle and its possible
 failure\, and sharp two-sided Green function estimates. The results on
 the boundary Harnack principle completely cover the corresponding
 earlier results in the case of half-space. The Green function
 estimates extend the corresponding earlier estimates in the case of
 half-space to  bounded $C^{1\, 1}$ open sets.  Joint work with Soobin
 Cho\, Panki Kim and Renming Song.
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250219T094500
DTEND;TZID=Europe/Berlin:20250219T102500
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:postersession@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Center for Interdisciplinary Research (ZiF)
STATUS:CONFIRMED
SUMMARY:Featured Poster Session
DESCRIPTION:
 This will be a gong show-style poster marathon, supplementing the
 featured poster sessions. It will enable every participant that brings
 a poster a very short (60-120 sec) flash/lightning talk highlighting
 their results, where each poster can be advertised before the actual
 poster session opens.
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250219T110000
DTEND;TZID=Europe/Berlin:20250219T123000
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:photo@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Center for Interdisciplinary Research (ZiF)
STATUS:CONFIRMED
SUMMARY:Talk of 
DESCRIPTION:\n\n
 Title. tba\n\n
 Abstract.
  tba
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250219T135000
DTEND;TZID=Europe/Berlin:20250219T140000
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:kangm@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Main University Building (UHG), Lecture Hall H16
STATUS:CONFIRMED
SUMMARY:Talk of Myungjoo Kang
DESCRIPTION:Myungjoo Kang (SNU)\n\n
 Title. Implicit Surface Reconstruction: A PDE-Guided Deep Learning
 Approach\n\n
 Abstract.
  In this presentation\, we introduce an advanced deep learning approach
 for reconstructing surfaces from unorganized point clouds. By
 leveraging an implicit surface representation through a level set
 function\, our method ensures watertight results and seamlessly adapts
 to various topologies. We employ the p-Poisson equation to precisely
 learn the signed distance function (SDF)\, improving accuracy through
 a variable splitting strategy that incorporates the SDF gradient as an
 auxiliary variable. Additionally\, we enforce a curl-free condition on
 the auxiliary variable to exploit the irrotational nature of
 conservative vector fields. Our numerical results illustrate that this
 strategic integration of partial differential equations and key vector
 field characteristics efficiently reconstructs high-quality surfaces
 without the need for prior surface knowledge.
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250220T090000
DTEND;TZID=Europe/Berlin:20250220T094000
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:jung@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Main University Building (UHG), Lecture Hall H16
STATUS:CONFIRMED
SUMMARY:Talk of Jinwook Jung
DESCRIPTION:Jinwook Jung (Hanyang)\n\n
 Title. Modulated energy estimates for singular kernels and their
 applications\n\n
 Abstract.
  In this talk\, we provide modulated interaction energy estimates for
 the kernel $K(x) = |x|^{-\alpha}$ with $\alpha \in (0\,d)$\, and their
 applications. The proof relies on a dimension extension argument for
 an elliptic operator and its commutator estimates. For the
 applications\, we first discuss the quantified asymptotic limit of
 kinetic equations with singular nonlocal interactions. We show that
 the aggregation equations and the isothermal or pressureless Euler
 system with singular interaction kernels are rigorously derived.
 Second\, we employ the estimates to establish the well-posedness
 theories in Hölder spaces for the kinetic and fluid equations
 involving singular interaction kernels\, mainly about inviscid
 $\alpha$-surface quasi-geostrophic ($\alpha$-SQG) equations and
 kinetic Cucker-Smale model.  This talk is based on the collaboration
 with Y.-P. Choi (Yonsei Univ.) and J. Kim (Ajou Univ.).
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250220T094500
DTEND;TZID=Europe/Berlin:20250220T101000
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:kimjm@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Main University Building (UHG), Lecture Hall H16
STATUS:CONFIRMED
SUMMARY:Talk of Jongmyeong Kim
DESCRIPTION:Jongmyeong Kim (Academia Sinica)\n\n
 Title. Holder regularity of fractional Laplacian on manifold\n\n
 Abstract.
  ABP estimate is important key step in Kyrlov-Safonov theory to achieve
 Holder regularity. I will introduce nonlocal ABP estimate on the
 hyperbolic space which generalize the result of Caffarelli and
 Silvestre on oneside and the result of Wang and Zhang on otherside. If
 time permit I will introduce (ongoing) Holder estimate for jump type
 Dirichlet form on the small class of Riemannian manifolds which
 involves the hyperbolic space.
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250220T101500
DTEND;TZID=Europe/Berlin:20250220T104000
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:hong@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Main University Building (UHG), Lecture Hall H16
STATUS:CONFIRMED
SUMMARY:Talk of Seokchang Hong
DESCRIPTION:Seokchang Hong (Bielefeld)\n\n
 Title. Strichartz estimates for the half Klein–Gordon equation on
 asymptotically flat backgrounds and applications to Dirac
 equations\n\n
 Abstract.
  The aim of this talk is to establish the $L^2_t$-endpoint Strichartz
 estimate for (half) Klein–Gordon equations on a weakly
 asymptotically flat space-time. Using the results by
 Metcalfe–Tataru\, we construct an outgoing parametrix for the
 operators via the phase space transform. Although the Klein–Gordon
 equation does not obey the scaling symmetry\, the scaling argument
 plays a crucial role and hence we can restrict ourselves to the
 operators localised in the unit scale. Consequently\, we obtain the
 dispersive inequality\, which is exactly same as the classical one\,
 and then establish the endpoint Strichartz estimates. As an
 application of this result\, we obtain the global well-posedness and
 scattering for cubic Dirac equation on a weakly asymptotically flat
 space-time for $H^s$-data\, $s>1$.  This talk is based on a joint work
 with Sebastian Herr.
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250220T111500
DTEND;TZID=Europe/Berlin:20250220T114000
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:schippa@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Main University Building (UHG), Lecture Hall H16
STATUS:CONFIRMED
SUMMARY:Talk of Robert Schippa
DESCRIPTION:Robert Schippa (UC Berkeley)\n\n
 Title. Quantified decoupling estimates and applications\n\n
 Abstract.
  In 2004 Bourgain proved a qualitative trilinear moment inequality for
 exponential sums and raised the question for quantitative estimates.
 Here we show quantitative estimates. The proof combines decoupling
 iterations with semi-classical Strichartz estimates.  Secondly\, we
 improve on Bourgain’s well-posedness result for the periodic KP-II
 equation. The latter part of the talk is based on joint work with
 Sebastian Herr and Nikolay Tzvetkov.
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250220T114500
DTEND;TZID=Europe/Berlin:20250220T121000
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:schenke@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Main University Building (UHG), Lecture Hall H16
STATUS:CONFIRMED
SUMMARY:Talk of Andre Schenke
DESCRIPTION:Andre Schenke (NYU Courant)\n\n
 Title. Non-uniqueness of Leray–Hopf solutions for the 3$D$
 fractional Navier–Stokes equations perturbed by transport noise\n\n
 Abstract.
  For the 3$D$ fractional Navier–Stokes equations perturbed by
 transport noise\, we prove the existence of infinitely many Hölder
 continuous analytically weak\, probabilistically strong Leray–Hopf
 solutions starting from the same deterministic initial velocity field.
 Our solutions are global in time and satisfy the energy inequality
 pathwise on a non-empty random interval $[0\,𝜏]$. In contrast to
 recent related results\, we do not consider an additional
 deterministic suitably chosen force f in the equation. In this
 unforced regime\, we prove the first result of Leray–Hopf
 nonuniqueness for fractional Navier–Stokes equations with any kind
 of stochastic perturbation. Our proof relies on convex integration
 techniques and a flow transformation by which we reformulate the SPDE
 as a PDE with random coefficients.
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250220T140000
DTEND;TZID=Europe/Berlin:20250220T142500
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:ling@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Main University Building (UHG), Lecture Hall H16
STATUS:CONFIRMED
SUMMARY:Talk of Chengcheng Ling
DESCRIPTION:Chengcheng Ling (Augsburg)\n\n
 Title. Quantitative approximation of stochastic kinetic equations:
 from discrete to continuum\n\n
 Abstract.
  We study the strong convergence of a generic tamed Euler–Maruyama
 (EM) scheme for the kinetic type stochastic differential equation
 (SDE) (also known as second order SDE) driven by $\alpha$-stable type
 noise with $\alpha\in(1\,2]$. We show that when the drift exhibits a
 relatively low regularity: anisotropic $\beta$-Hölder continuity with
 $\beta >1 - \frac{\alpha}{2}$\, the corresponding tamed EM converges
 with a convergence rate $(\frac{1}{2} + \frac{\beta}{\alpha(1+\alpha)}
 \wedge \frac{1}{2})$\, which aligns with the results of  first-order
 SDEs.  This talk is based on the work arXiv:2409.05706 (joint with
 Zimo Hao and Khoa Lê)  and the work arXiv:2412.05142.
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250220T143000
DTEND;TZID=Europe/Berlin:20250220T145500
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:kimk@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Main University Building (UHG), Lecture Hall H16
STATUS:CONFIRMED
SUMMARY:Talk of Kihyun Kim
DESCRIPTION:Kihyun Kim (SNU)\n\n
 Title. On classification of the rates of concentration of bubbles for
 the radial critical nonlinear heat equation in large dimensions\n\n
 Abstract.
  In my talk given online last December\, I discussed my joint work with
 Frank Merle (IHES and CY Cergy-Paris Université) on classification of
 bubble tower dynamics for the radial critical nonlinear heat equation
 in large dimensions. In this talk\, I will recall the main result and
 talk about a formal derivation of the concentration rates of each
 bubble. If time permits\, I will also discuss the scheme of the proof.
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250220T150000
DTEND;TZID=Europe/Berlin:20250220T152500
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:weidner@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Main University Building (UHG), Lecture Hall H16
STATUS:CONFIRMED
SUMMARY:Talk of Marvin Weidner
DESCRIPTION:Marvin Weidner (Barcelona)\n\n
 Title. Boundary regularity for nonlocal equations\n\n
 Abstract.
  There are significant differences between local and nonlocal problems
 when it comes to the boundary behavior of solutions. For instance\, it
 is a well known fact that $s$-harmonic functions (i.e. solutions to
 nonlocal elliptic equations governed by the fractional Laplacian) are
 in general not better than $C^s$ up to the boundary.  As a
 consequence\, in recent years there has been a huge interest in the
 boundary behavior of solutions to nonlocal equations. By now\, the
 boundary regularity is well understood for the fractional Laplacian
 and for $2s$-stable nonlocal operators\, however very little is known
 about the natural class of nonlocal operators with inhomogeneous
 kernels.  In this talk\, I will present recent progress on the study
 of the inhomogeneous case\, achieved in collaboration with Xavier
 Ros-Oton.
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250220T160000
DTEND;TZID=Europe/Berlin:20250220T162500
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:kimm@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Main University Building (UHG), Lecture Hall H16
STATUS:CONFIRMED
SUMMARY:Talk of Minhyun Kim
DESCRIPTION:Minhyun Kim (Hanyang)\n\n
 Title. Optimal boundary regularity and Green function estimates\n\n
 Abstract.
  We study the optimal $C^s$ boundary regularity for solutions to
 nonlocal elliptic equations with Hölder continuous coefficients in
 divergence form in $C^{1\,\alpha}$ domains. As an application of our
 results\, we establish sharp two-sided Green function estimates in
 $C^{1\,\alpha}$ domains.  This talk is based on joint work with Marvin
 Weidner.
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250220T163000
DTEND;TZID=Europe/Berlin:20250220T165500
DTSTAMP:20260416T015853Z
END:VEVENT
BEGIN:VEVENT
UID:leeka@irtg.math.uni-bielefeld.de/workshop2025
LOCATION:Bielefeld University, Main University Building (UHG), Lecture Hall H16
STATUS:CONFIRMED
SUMMARY:Talk of Ki-Ahm Lee
DESCRIPTION:Kim-Ahm Lee (SNU)\n\n
 Title. Degenerate Nonlinear Partial Differential Equations in
 Curvature Flows\n\n
 Abstract.
  In this talk\, we are going to discuss Degenerate Nonlinear Partial
 Differential Equations in Curvature Flows with a noncompact graph as
 its initial hypersurface. The solution can be expressed as a graph
 with infinite height on the boundary of its support. We will discuss
 uniform estimates of the solution up to the infinite height\, the
 evolution of the boundary of its support\, and its geometric
 properties preserved under the flow.
CLASS:PUBLIC
DTSTART;TZID=Europe/Berlin:20250220T170000
DTEND;TZID=Europe/Berlin:20250220T174000
DTSTAMP:20260416T015853Z
END:VEVENT
END:VCALENDAR