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Wed, 08. Jul at 10:00
HVP 11 a, R.313
Computational lower bounds in clustering and ranking
Abstract. In this talk, we will speak about computational lower bounds. After an extended general introduction that presents these tools, and we will focus more particularly on the problem of clustering.
Wed, 08. Jul at 10:00
HVP 11 a, R.313
Wed, 08. Jul at 13:15
Room 3.007 John v...
Vanishing of weight one syzygies of projective varieties
Abstract. In this talk, we study conditions under which weight one Koszul cohomology vanishes on projective varieties. As corollary of more general results, we obtain statements on the so-called property (M_q) reflecting on the higher syzygies of minimal surfaces and higher dimensional projective varieties. We also provide lower bounds on l such that L = l B and adjoint L' = K_X + l B satisfies (M_q) for base point free and ample line bundle B on a projective variety X. We also generalize the effective bounds on Gonality conjecture by W. Niu and J. Park to rational surfaces and certain higher dimensional Fano varieties which is later on used to prove the sharpness of our lower bounds. Property (M_q) is complementary to property (N_p) though it is far less studied. Notably, our bounds for property (M_q) for both L and L' are equal to or better than existing bounds for property (N_p), as established by other authors—particularly in relation to Mukai's conjecture and its higher-dimensional analogues. By considering both properties (M_q) and (N_p), we gain a significantly deeper understanding of the minimal free resolution., we gain a significantly deeper understanding of the minimal free resolution.
Wed, 08. Jul at 16:30
IMoS 3003
Linearly-exponential checking is enough for the Lonely Runner Conjecture
Abstract
Thu, 09. Jul at 11:15
Humboldt-Universi...
A posteriori existence verification from nonconforming discretisations
Abstract. A Newton-Kantorovich argument can turn a computed approximation into a certificate for the existence and local uniqueness of a regular solution of a nonlinear PDE. This talk presents such an a posteriori verification framework for nonconforming finite element discretisations with application to a fourth-order formulation for the stationary 2D Navier-Stokes equations. The central difficulty is to obtain a guaranteed lower bound for the continuous inf-sup constant of the linearised operator. We derive such a bound from a discrete inf-sup constant and a novel nonconforming approximation error estimate for linear auxiliary problems.
Thu, 09. Jul at 14:00
Freie Universität...
A completion theorem in genuine G-spectra for profinite G
Fri, 10. Jul at 14:15
FU (T9)
Rare events in particle systems and conservative stochastic PDE
Abstract
Fri, 10. Jul at 14:15
FU (T9)
Fri, 10. Jul at 14:30
1.023
Symplectic quadrics in projective 3-space
Abstract
Fri, 10. Jul at 16:00
1.023
Fukaya categories of conical symplectic resolutions
Abstract
Mon, 13. Jul at 10:00
SR 115, Arnimallee 3
Mon, 13. Jul at 11:30
Weierstrass Lectu...
Metastability for the 2-pattern Hopfield model and general product chains
Abstract. The Hopfield model is a mean-field spin system designed to store a set of patterns as ground states of its Hamiltonian, providing a simple mathematical model of associative memory. At low temperature, the associated Glauber–Metropolis dynamics is metastable: started near a stored pattern, the system remains in its vicinity for an exponentially long time before an abrupt transition towards another pattern. In this talk I discuss the metastable behavior of the model with two stored patterns. After a brief introduction to the potential-theoretic approach to metastability — capacities, equilibrium potentials, and the variational principles that connect them to metastable transition times — I show how the decomposition of the spin sites into the sets where the two patterns agree and disagree reduces the dynamics, via an exact lumping, to a product of two Curie–Weiss-type chains. We will show how this tensorization structure allows metastability to be propagated from the component chains to the full model — capacities of the product chain are controlled by those of its marginals, and one obtains sharp Eyring–Kramers-type estimates for the transition times between the stored patterns. Based on ongoing work with Elena Pulvirenti and Martin Slowik.
Mon, 13. Jul at 13:15
Rudower Chaussee ...
Sparse trigonometric approximation of function classes of mixed smoothness and applications
Tue, 14. Jul at 10:00
WIAS ESH and online
A Proximal Discontinuous Galerkin Method for Total Bounded Variation Based Image Denoising
Tue, 14. Jul at 11:15
1.023 (BMS Room, ...
A remark on Gaiotto's conformal limit correspondence and the geometric Langlands correspondence
Abstract. In this talk, I will illustrate that the Gaiotto correspondence, composed with the Hausel-Thaddeus mirror symmetry, is exactly the same as the oper case of the geometric Langlands correspondence due to Beilinson-Drinfeld. In 2014, Gaiotto conjectured a canonical correspondence between the moduli space of spectral curves for a G-Hitchin system on a curve X and the moduli of G-opers on X, where G is a simple and simply connected complex Lie group. Due to the fact that opers in this context are quantum curves to the topological recursion community, I worked with my collaborators and solved this conjecture (Dumitrescu-Fredrickson-Kydonakis-Mazzeo-Mulase-Neitzke 2016). Of course these moduli spaces are isomorphic. What was new in this work is the construction of a canonical map. When I explained this map to Gaitsgoy at IHES in 2016, he said, "I think I know the map." My talk is a 10-year-too-late report submission to his comment. Indeed, the map comes from the geometric Langlands correspondence!
Tue, 14. Jul at 11:15
1.023 (BMS Room, ...
Tue, 14. Jul at 14:15
WIAS, Erhard-Schm...
Pattern formation and symmetry breaking for a family of functionals and their intrinsic nonlocal curvature
Abstract
Tue, 14. Jul at 14:15
WIAS, Erhard-Schm...
Wed, 15. Jul at 10:00
Weierstrass-Insti...
A Bernstein-von Mises Theorem for indirect measurement models with nonlinear unbounded forward operators
Abstract. Motivated by recently proposed Gaussian process solvers for semilinear elliptic PDEs [1], we consider Bayesian nonparametric inference for indirect measurement models with nonlinear unbounded forward operators. We establish optimal posterior contraction rates and a nonparametric Bernstein-von Mises theorem in strong Sobolev norms (H^{2-d/2}) for d ≤ 3. Our results show that unbounded forward maps may lead to stronger Bernstein-von Mises results in L^p-type norms. This is interesting in light of the conventional statistical wisdom that the nonparametric Bernstein-von Mises phenomenon is only feasible in ‘weak’ metrics. [1] Yifan Chen, Bamdad Hosseini, Houman Owhadi, Andrew M. Stuart. Solving and learning nonlinear PDEs with Gaussian processes, Journal of Computational Physics, 447: 110668 (2021)
Wed, 15. Jul at 11:30
Weierstrass Lectu...
Asymptotic democracy for finite nonlinear Pólya urns
Abstract. In this presentation, we will study Pólya urn models — specifically, a generalization involving an arbitrary finite number of urns and where the addition of a ball to each urn is proportional to a (non-linear) function f of the number of balls already present in that urn. After introducing the continuous-time modeling of this system and presenting two fundamental results regarding monopoly and leadership — more precisely, monopoly (resp. leadership) occurs if and only if $1/f(i)$ (resp. $1/f(i)^2$) is summable —, we will outline a new "democracy" theorem that emerges with weighting functions characterized by relatively slow growth.
Wed, 15. Jul at 14:00
WIAS, Erhard-Schm...
Dynamics of a 3D rimming flow
Abstract
Wed, 15. Jul at 16:00
Thu, 16. Jul at 16:15
TU Berlin, MA 043
Thu, 16. Jul at 17:15
TU Berlin, MA 043
Wed, 22. Jul at 16:30
IMoS 3003
Operatopes, Operanoids, and Noncommutative zonoids
Wed, 29. Jul at 14:15
WIAS, Erhard-Schm...
Global existence and large time behaviour of nonlinear reaction-diffusion systems
Abstract
Wed, 04. Nov at 14:15
R. 405/405
Thu, 17. Dec at 16:30
EN 058
Drawing algebraic curves in OSCAR
Abstract. I will talk about how to visualize real plane algebraic curves given as the zero set of a polynomial in two variables using Oscar.jl. I will highlight performance and exactness issues using real world examples.