FB 6 Mathematik/Informatik

Institut für Mathematik


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Kolloquium

30.05.2018 um 17:15 Uhr in Raum 69/125

Prof. Dr. Ngô Việt Trung (Institute of Mathematics Hanoi, Vietnam)

Depth of powers of homogeneous ideals

Let I be an arbitrary homogeneous ideal in in a polynomial ring R. Brodmann showed that the function depth R/It = dim R - pd R/It (where pd is the projective dimension) is always a constant for t >> 0. In other word, it is a convergent function. Subsequent works have indicated that this function may behave wildly. Herzog and Hibi conjectured that any convergent non-negative numerical function is the depth function of powers of a homogeneous ideal. We will solve this conjecture by showing that any convergent non-negative numerical function is the depth function of powers of a monomial ideal. The lecture is about the basic ideas of the solution, which are rather elementary and should be understandable for everybody.

06.06.2018 um 17:15 Uhr in Raum 69/125

Prof. Dr. Sylvie Roelly (Universität Potsdam)

Random Sphere Packing

We consider a system of hard balls in Euclidean space, undergoing random dynamics and interacting via a mutual attraction force. Such stochastic evolutions converge asymptotically in time towards equilibrium states, which are connected with the famous geometry problem of close-packing of equal spheres.

Oberseminar Angewandte Analysis

29.05.2018 um 14:15 Uhr in Raum 69/E23

Markus Wageringel (Universität Osnabrück )

Algebraic Geometry of Local Mixtures?

05.06.2018 um 14:15 Uhr in Raum 69/E23

Anna Veselovska (Universität Lübeck)

Parameter Estimation of a Sum of Bivariate Non-Harmonic Frequencies

 

Oberseminar Stochastik

29.05.2018 um 12:00 Uhr in Raum 69/E15

Jens Grygierek (Universität Osnabrück)

TBA

05.06.2018 um 12:00 Uhr in Raum 69/E15

Grace Itunuoluwa Akinwande (Universität Osnabrück)

TBA

Oberseminar Algebra

Kollegseminar „Kombinatorische Strukturen in der Geometrie“

29.05.2018 um 16:15 Uhr in 69/125:

Carina Betken (Universität Osnabrück)

Fluctuations in a general preferential attachment model via Stein's method

We look at the indegree of a uniformly chosen vertex in a preferential attachment random graph, where the probability that a newly arriving vertex  connects to an older vertex  is proportional to a sublinear function of the indegree of the older vertex at that time. We provide rates of convergence for the total variation distance between this degree distribution and an asymptotic power-law distribution as the number of vertices tends to .

05.06.2018 um 16:15 Uhr in 69/125:

Jan Marten Brunink (Universität Osnabrück)

TBA

Oberseminar Topologie

29.05.2018 um 14:15 Uhr in 69/E15:

Daniel Harrer  (Universität Essen)

An explicit realization functor between motives

We construct an explicit comparison functor from Voevodsky's geometric motives to the bounded derived category of Nori motives. It is triangulated, monoidal and compatible with the Betti realization on both sides. The argument uses the following three main ingredients:
(a) translating finite correspondences to multi-valued morphisms (after Rydh, Suslin, Voevodsky and others),
(b) a theory of étale/Nisnevich covers on diagrams of finite correspondences (generalizing results by Friedlander),
(c) Nori's (co)homological analogue of topological cell-structures on both varieties and finite correspondences (extending on work by Nori, Huber and Müller-Stach).

05.06.2018 um 14:15 Uhr in 69/E15:

Adeel Khan (Universität Regensburg)

The motivic Pontrjagin-Thom isomorphism

We will explain an analogue in motivic homotopy theory of (a generalized form of) the Pontrjagin-Thom isomorphism, computing stable homotopy groups of spheres in terms of framed bordisms.