Open intersection numbers, matrix models and integrability
Montag, 2.2.15, 16:15-17:15, Raum 404, Eckerstr. 1
In my talk I will discuss a family of matrix models, which describes the generating functions of intersection numbers on moduli spaces both for open and closed Riemann surfaces. Linear (Virasoro\bW-constraints) and bilinear (KP\bMKP integrable hierarchies) equations follow from the matrix model representation. \n\n
De Rham Witt complex
Dienstag, 3.2.15, 10:30-11:30, Raum 403, Eckerstr. 1
Anti-Self-Dual Yang-Mills connections on stable bundles over albebraic surfaces
Dienstag, 3.2.15, 16:00-17:00, Raum 404, Eckerstr. 1
We will have a carefull study about sir Donaldson´s paper "Anti-Self-Dual Yang-Mills connections over Algebraic surfaces and stable vector bundles",which gives a proof about the 2 dimensional case of Hitchin-Kobayashi correspondence,by the techniques of choosing good gauge to obtain the the convergence of connections under Yang Mills flow to Hermitian-Yang-Mills connection.
De Rham Witt complex
Mittwoch, 4.2.15, 10:30-11:30, Raum 403, Eckerstr. 1
Partially definable forcing and weak arithmetics
Mittwoch, 4.2.15, 16:30-17:30, Raum 404, Eckerstr. 1
Given a nonstandard model M of arithmetic we want to expand it\nby interpreting a binary relation symbol R such that R^M does something\nprohibitive, e.g. violates the pigeonhole principle in the sense that R^M\nis a bijection from n+1 onto n for some (nonstandard) n in M. The goal is\nto do so saving as much as possible from ordinary arithmetic. More\nprecisely, we want the expansion to satisfy the least number principle for\na class of formulas as large as possible. We describe a forcing method to\nproduce such expansions and revisit the most important results in the\narea.\n
De Rham Witt complex
Donnerstag, 5.2.15, 10:30-11:30, Raum 403, Eckerstr. 1
From twisted cubics to exotic Ricci-flat manifolds via G_2
Donnerstag, 5.2.15, 17:00-18:00, Hörsaal II, Albertstr. 23b
Ramification theory for D-modules in positive characteristic
Freitag, 6.2.15, 10:15-11:15, Raum 404, Eckerstr. 1
Abstract: On a smooth variety in positive characteristic, a\nvector bundle carrying an action of the sheaf of\ndifferential operators is called a stratified bundle. I\nwill give a brief introduction into the theory of these\nobjects and I will explain the notion of regular\nsingularity for stratified bundles. This notion is closely\nrelated to tame ramification of étale coverings. For\nstratified bundles on a curve, I will sketch the beginning\nof a higher ramification theory of stratified bundles,\nanalog to higher ramification theory of étale coverings.
Causal Discovery From Bivariate Relationships
Freitag, 6.2.15, 11:30-12:30, Raum 404, Eckerstr. 1
In Causal Discovery, we ask which models from a certain causal model class\n(e.g., DAGs) would be consistent with a given dataset. Many causal discovery\nalgorithms are based on conditional independence testing. However, conditional\nindependence is difficult to test, especially when parametric assumptions like\nnormality cannot be made. Hence, we ask to what extent causal discovery is still\npossible when we restrict our attention to only pairwise relationships, for\nwhich a wide variety of both parametric and non-parametric statistical\nindependence tests are available. Suprisingly, we find that the entire class of\nedge-maximal DAGs that are consistent with a given set of pairwise dependencies\ncan be described by a single graph, which can be constructed by a rather simple\nalgorithm. Furthermore, we give a precise characterization of how much\ndiscrimination power we lose by not looking at conditional independencies.\nFinally, we empirically investigate the failed discovery rate of the pairwise\napproach -- assuming a correct DAG exists, how often is it rejected? -- and\ncompare the results to those the partial correlation based PC algorithm.\n
Higher Spins & Strings
Freitag, 6.2.15, 14:00-15:00, Raum 404, Eckerstr. 1
K-Theory and the Classification of Symmetric Spaces
Freitag, 6.2.15, 15:45-16:45, Raum 404, Eckerstr. 1
Riemannian symmetric spaces have been classified using root spaces of some underlying Lie algebra. In this talk we sketch how K-theoretical tools can be used for this purpose, and show that these methods can also be applied to inductive limits, where classical methods no longer seem to be productive.
Defects and the Landau-Ginzburg / CFT correspondence
Freitag, 6.2.15, 17:00-18:00, Raum 404, Eckerstr. 1
Some N=2 superconformal field theories have two rather distinct descriptions. Namely 1) as the infrared fixed point of an N=2 Landau-Ginzburg model, and 2) directly in terms of conformal blocks for the N=2 superconformal algebra. The dominant mathematical notion in 1) is that of matrix factorisations, while in 2) - unsurprisingly - it is the representation theory of the N=2 superconformal algebra. Considering CFTs in the presence of defect lines in these two descriptions provides interesting and surprising relations. In this talk I will focus on "orbifold-equivalence" as an example of such a relation. This is joint work with Nils Carqueville and Ana Ros Camacho.
Donagi-Markman cubics and Hitchin systems
Montag, 9.2.15, 16:15-17:15, Raum 404, Eckerstr. 1
As discovered by Donagi and Markman, the existence of Lagrangian structure on a holomorphic family of abelian varieties\n(of appropriate dimension) depends on the vanishing of a certain local obstruction. In particular, the infinitesimal period map for the family\nmust be a section of the third symmetric power of the cotangent bundle to the base of the family. I will discuss recent work with U.Bruzzo\n(IJM, vol.25 (2), 2014 ) where we compute the Donagi-Markman cubic for the generalised Hitchin system. In particular, we show that the\nBalduzzi-Pantev formula holds along the maximal rank symplectic leaves.
Rate-independent damage models with spatial BV-regularization -- Existence & fine properties of solutions
Dienstag, 10.2.15, 14:15-15:15, Raum 226, Hermann-Herder-Str. 10
In this talk we address the existence of energetic solutions for a model of\npartial damage with a BV-gradient regularization in the damage variable.\nFurthermore, we discuss properties of energetic solutions that can be\nobtained in a setting where the damage variable is a characteristic function of \nsets with finite perimeter.
A new forcing order
Mittwoch, 11.2.15, 16:30-17:30, Raum 404, Eckerstr. 1
Codimension one foliation with a compact leaf
Freitag, 13.2.15, 10:15-11:15, Raum 404, Eckerstr. 1
Abstract: In this talk (based on a joint work with J. Pereira, F. Loray and F. Touzet), we will be interested in the study of codimension one foliations on compact Kähler manifold having a compact leaf. This leaf is then an embedded hypersurface whose normal bundle is topologically torsion and its holonomy representation reflects a major part of the information concerning the transversal dynamic of the foliation. We will be concerned with the following issues: existence of foliations having as a leaf a given hypersurface and foliations with abelian holonomy. Most of these results are stated in terms of Ueda theory and we will spend some time reviewing it.
Parameter selection for nonlinear modeling using L1 regularization
Freitag, 13.2.15, 11:30-12:30, Raum 404, Eckerstr. 1
A major goal in systems biology is to reveal potential drug targets for cancer therapy. A common property of cancer cells is the alteration of signaling pathways triggering cell-fate decisions resulting in uncontrolled proliferation and tumor growth. However, addressing cancer-specific alterations experimentally by investigating each node in the signaling network one after the other is difficult or even not possible at all. Here, we combine quantitative time-resolved data from different cell lines with non-linear modeling under L1 regularization, which is capable of detecting cell-type specific parameters. To adapt the least-squares numerical optimization routine to L1 regularization, sub-gradient strategies as well as truncation of proposed optimization steps were implemented. Likelihood-ratio tests were used to determine the optimal penalization strength resulting in a sparse solution in terms of a minimal number of cell-type specific parameters that is in agreement with the data. The uniqueness of the solution is investigated using the profile likelihood. Based on the minimal set of cell-type specific parameters experiments were designed for improving identifiability and to validate the model. The approach constitutes a general method to infer an overarching model with a minimum number of individual parameters for the particular models.
Simpliziale Homologie
Montag, 23.2.15, 09:00-10:00, Hörsaal II, Albertstr. 23b
Einführung in topologische Datenanalyse und persistente Homologie
Montag, 23.2.15, 10:30-11:30, Hörsaal II, Albertstr. 23b
Einführung in topologische Datenanalyse und persistente Homologie
Montag, 23.2.15, 13:30-14:30, Hörsaal II, Albertstr. 23b
Persistence of undercompressive phase boundaries for isothermal Euler equations including configurational forces and surface tension
Mittwoch, 25.2.15, 14:00-15:00, Hörsaal II, Albertstr. 23b
Persistence of undercompressive phase boundaries for isothermal Euler equations including configurational forces and surface tension
Mittwoch, 25.2.15, 14:00-15:00, Hörsaal II, Albertstr. 23b
The challenges of multiscale flow simulations
Mittwoch, 25.2.15, 14:45-15:45, Hörsaal II, Albertstr. 23b
Kramers- und Non-Kramers Phase Transitions in a Nonlocal Fokker-Planck Equation
Mittwoch, 25.2.15, 16:00-17:00, Hörsaal II, Albertstr. 23b
Coupled problems and code-coupling in two-phase flow problems
Mittwoch, 25.2.15, 16:45-17:45, Hörsaal II, Albertstr. 23b
A proof of a sharp interface limit for compressible phase change flows
Mittwoch, 25.2.15, 17:30-18:30, Hörsaal II, Albertstr. 23b
Surface tension and molecular dynamics
Donnerstag, 26.2.15, 09:00-10:00, Hörsaal II, Albertstr. 23b
Finite element methods for two-phase incompressible flows
Donnerstag, 26.2.15, 09:45-10:45, Hörsaal II, Albertstr. 23b
A combined finite volume discontinuous Galerkin approach for the sharp-interface tracking of multi-phase flow
Donnerstag, 26.2.15, 11:00-12:00, Hörsaal II, Albertstr. 23b
Diffuse Interface Models for Two-Phase Flows with Surfactants
Donnerstag, 26.2.15, 11:45-12:45, Hörsaal II, Albertstr. 23b
Jin-Xin's relaxation solvers with defect measures corrections
Donnerstag, 26.2.15, 12:30-13:30, Hörsaal II, Albertstr. 23b
An all-regime Lagrange-Projection like scheme for 2D homogeneous models for two-phase flows on unstructured meshes
Donnerstag, 26.2.15, 14:30-15:30, Hörsaal II, Albertstr. 23b
Nonconservative products in sedimentation transport models
Donnerstag, 26.2.15, 15:50-16:50, Hörsaal II, Albertstr. 23b
FCT-stabilized finite element level-set-based method for PDEs on surfaces and preservation of area and volume constraints for incompressible lipid membranes
Donnerstag, 26.2.15, 16:30-17:30, Hörsaal II, Albertstr. 23b
A two-phase fluid model for blubbly flows with phase transition
Donnerstag, 26.2.15, 17:35-18:35, Hörsaal II, Albertstr. 23b
A revisit of implicit finite volume methods
Freitag, 27.2.15, 09:00-10:00, Hörsaal II, Albertstr. 23b
An All-Speed Asymptotic-Preserving Method for the Relaxed Navier-Stokes-Korteweg Equations
Freitag, 27.2.15, 09:45-10:45, Hörsaal II, Albertstr. 23b
A Riemann Solver for Liquid-Vapor Flow with Latent Heat
Freitag, 27.2.15, 11:00-12:00, Hörsaal II, Albertstr. 23b