Browsing 1 - Oberwolfach Preprints (OWP) by MFO Scientific Program "OWLF 2013"

Now showing items 1-10 of 10

    • The algebraic combinatorial approach for low-rank matrix completion 

      [OWP-2013-05] Király, Franz J.; Theran, Louis; Ryota,Tomioka; Uno, Takeaki (Mathematisches Forschungsinstitut Oberwolfach, 2013-03-14)
      We propose an algebraic combinatorial framework for the problem of completing partially observed low-rank matrices. We show that the intrinsic properties of the problem, including which entries can be reconstructed, and ...

    • Algebraic Matroids with Graph Symmetry 

      [OWP-2014-02] Király, Franz J.; Rosen, Zvi; Theran, Louis (Mathematisches Forschungsinstitut Oberwolfach, 2014)
      This paper studies the properties of two kinds of matroids: (a) algebraic matroids and (b) finite and infinite matroids whose ground set have some canonical symmetry, for example row and column symmetry and transposition ...

    • An Explicit Formula for the Dirac Multiplicities on Lens Spaces 

      [OWP-2014-19] Boldt, Sebastian; Lauret, Emilio A. (Mathematisches Forschungsinstitut Oberwolfach, 2014)
      We present a new description of the spectrum of the (spin-) Dirac operator $D$ on lens spaces. Viewing a spin lens space $L$ as a locally symmetric space $\Gamma \setminus Spin(2m)/Spin(2m-1)$ and exploiting the representation ...

    • Mesh Ratios for Best-Packing and Limits of Minimal Energy Configurations 

      [OWP-2013-13] Bondarenko, A. V.; Hardin, Douglas P.; Saff, Edward B. (Mathematisches Forschungsinstitut Oberwolfach, 2013-06-10)
      For $N$-point best-packing configurations $\omega_N$ on a compact metric space $(A, \rho)$, we obtain estimates for the mesh-separation ratio $\gamma(\rho_N , A)$, which is the quotient of the covering radius of $\omega_N$ ...

    • Obtaining Error-Minimizing Estimates and Universal Entry-Wise Error Bounds for Low-Rank Matrix Completion 

      [OWP-2013-12] Király, Franz J.; Theran, Louis (Mathematisches Forschungsinstitut Oberwolfach, 2013-06-10)
      We propose a general framework for reconstructing and denoising single entries of incomplete and noisy entries. We describe: effective algorithms for deciding if and entry can be reconstructed and, if so, for reconstructing ...

    • On Concentrators and Related Approximation Constants 

      [OWP-2013-14] Bondarenko, A. V.; Prymak, A.; Radchenko, D. (Mathematisches Forschungsinstitut Oberwolfach, 2013-06-10)
      Pippenger ([Pip77]) showed the existence of (6m, 4m, 3m, 6)-concentrator for each positive integer m using a probabilistic method. We generalize his approach and prove existence of (6m, 4m, 3m, 5.05)-concentrator (which ...

    • On the autonomous metric on groups of Hamiltonian diffeomorphisms of closed hyperbolic surfaces 

      [OWP-2013-18] Brandenbursky, Michael (Mathematisches Forschungsinstitut Oberwolfach, 2013-07-23)
      Let $\Sigma_g$ be a closed hyperbolic surface of genus $g$ and let Ham($\Sigma_ g$) be the group of Hamiltonian diffeomorphisms of $\Sigma_g$. The most natural word metric on this group is the autonomous metric. It has ...

    • Right Simple Singularities in Positive Characteristic 

      [OWP-2013-28] Greuel, Gert-Martin; Nguyen, Hong Duc (Mathematisches Forschungsinstitut Oberwolfach, 2013)
      We classify isolated singularities $f \in K[[x_1,...,x_n]]$, which are simple, i.e. have no moduli, w.r.t. right equivalence, where $K$ is an algebraically closed field of characteristic $p>0$. For $K=\mathbb{R}$ or ...

    • Spherical Actions on Flag Varieties 

      [OWP-2014-04] Avdeev, Roman; Petukhov, Alexey (Mathematisches Forschungsinstitut Oberwolfach, 2014-04-25)
      For every finite-dimensional vector space $V$ and every $V$ -flag variety $X$ we list all connected reductive subgroups in $GL(V)$ acting spherically on $X$.

    • Supertropical Quadratic Forms I 

      [OWP-2013-27] Knebusch, Manfred; Rowen, Louis; Izhakian, Zur (Mathematisches Forschungsinstitut Oberwolfach, 2013)
      We initiate the theory of a quadratic form q over a semiring $R$. As customary, one can write $q(x+y)=q(x)+q(y)+b(x,y)$, where b is a companion bilinear form. But in contrast to the ring-theoretic case, the companion ...