Browsing by MSC "05"

Now showing items 81-100 of 102

    • 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 Gauss Algebra of Toric Algebras 

      [OWP-2018-07] Herzog, Jürgen; Jafari, Raheleh; Nasrollah Nejad, Abbas (Mathematisches Forschungsinstitut Oberwolfach, 2018-04-25)
      Let $A$ be a $K$-subalgebra of the polynomial ring $S=K[x_1,\ldots,x_d]$ of dimension $d$, generated by finitely many monomials of degree $r$. Then the Gauss algebra $\mathbb{G}(A)$ of $A$ is generated by monomials of ...

    • On the Invariants of the Cohomology of Complements of Coxeter Arrangements 

      [OWP-2018-21] Douglass, J. Matthew; Pfeiffer, Götz; Röhrle, Gerhard (Mathematisches Forschungsinstitut Oberwolfach, 2018-10-22)
      We refine Brieskorn's study of the cohomology of the complement of the reflection arrangement of a finite Coxeter group W. As a result we complete the verification of a conjecture by Felder and Veselov that gives an explicit ...

    • On Vietoris-Rips Complexes of Ellipses 

      [OWP-2017-11] Adamaszek, Michal; Adams, Henry; Reddy, Samadwara (Mathematisches Forschungsinstitut Oberwolfach, 2017-04-25)
      For $X$ a metric space and $r > 0$ a scale parameter, the Vietoris–Rips complex $VR_<(X; r)$ (resp. $VR_≤(X; r)$) has $X$ as its vertex set, and a finite subset $\sigma \subseteq X$ as a simplex whenever the diameter of ...

    • The Pelletier-Ressayre Hidden Symmetry for Littlewood-Richardson Coefficients 

      [OWP-2020-18] Grinberg, Darij (Mathematisches Forschungsinstitut Oberwolfach, 2020-09-08)
      We prove an identity for Littlewood–Richardson coefficients conjectured by Pelletier and Ressayre. The proof relies on a novel birational involution defined over any semifield.

    • 0732 - Permutation Groups 

      [OWR-2007-37] (2007) - (05 Aug - 11 Aug 2007)
      Abstract. The theory of permutation groups is essentially the theory of symmetry for mathematical and physical systems, and therefore has major impact in diverse areas of mathematics. Recent significant advances in permutation ...

    • Plethysms, replicated Schur functions and series, with applications to vertex operators 

      [OWP-2010-12] Fauser, Bertfried; Jarvis, Peter D.; King, Ronald C. (Mathematisches Forschungsinstitut Oberwolfach, 2010-03-14)
      Specializations of Schur functions are exploited to define and evaluate the Schur functions $s_\lambda [\alpha X]$ and plethysms $s_\lambda [\alpha s_\nu(X))]$ for any $\alpha$-integer, real or complex. Plethysms are then ...

    • Positive Margins and Primary Decomposition 

      [OWP-2012-06] Kahle, Thomas; Rauh, Johannes; Sullivant, Seth (Mathematisches Forschungsinstitut Oberwolfach, 2012)
      We study random walks on contingency tables with fixed marginals, corresponding to a (log-linear) hierarchical model. If the set of allowed moves is not a Markov basis, then there exist tables with the same marginals that ...

    • 2313 - Random Graphs: Combinatorics, Complex Networks and Disordered Systems 

      [OWR-2023-16] (2023) - (26 Mar - 31 Mar 2023)
      Since the turn of the millennium the theory of random graphs has advanced by leaps and bounds. Random graphs have found very many applications, and many unexpected applications, in a remarkable variety of disciplines, and ...

    • 0904 - Random Trees 

      [OWR-2009-3] (2009) - (18 Jan - 24 Jan 2009)
      The meeting was devoted to random trees, a central concept in mathematics that provides a key way of thinking about relationships between objects such as particles in a fluid, individuals in a population, or labels in a ...

    • Rank Deviations for Overpartitions 

      [OWP-2023-11] Lovejoy, Jeremy; Osburn, Robert (Mathematisches Forschungsinstitut Oberwolfach, 2023-07-12)
      We prove general fomulas for the deviations of two overpartition ranks from the average, namely \begin{equation*} \overline{D}(a, M) := \sum_{n \geq 0} \Bigl( \overline{N}(a, M, n) - \frac{\overline{p}(n)}{M} \Bigr) q^n ...

    • Some Homological Properties of Borel Type Ideals 

      [OWP-2022-03] Herzog, Jürgen; Moradi, Somayeh; Rahimbeigi, Masoomeh; Zhu, Guangjun (Mathematisches Forschungsinstitut Oberwolfach, 2022-02-01)
      We study ideals of Borel type, including $k$-Borel ideals and $t$-spread Veronese ideals. We determine their free resolutions and their homological shift ideals. The multiplicity and the analytic spread of equigenerated ...

    • 2103 - Spatial Networks and Percolation (hybrid meeting) 

      [OWR-2021-4] (2021) - (17 Jan - 23 Jan 2021)
      The classical percolation problem is to find whether there is an infinite connected component in a random set created by removing edges from a $d$-dimensional lattice, independently at random. Since its introduction into ...

    • 0519 - Stochastic Analysis and Non-Classical Random Processes 

      [OWR-2005-23] (2005) - (08 May - 14 May 2005)
      The workshop focused on recent developments in the theory of stochastic processes and flows, with special emphasis on emerging new classes of processes, as well as new objects whose limits are expected to coincide with ...

    • 2211a - The Laguerre-Pólya Class and Combinatorics 

      [OWR-2022-13] (2022) - (13 Mar - 19 Mar 2022)
      The talks at the workshop were focused on zero localization and zero finding of entire functions, with applications to analytic number theory and combinatorics. The discussions included specific areas such as stable and ...

    • 1106 - Topological and Geometric Combinatorics 

      [OWR-2011-8] (2011) - (06 Feb - 12 Feb 2011)
      The 2011 Oberwolfach meeting “Topological and Geometric Combinatorics” was organized by Anders Björner (Stockholm), Gil Kalai (Jerusalem), Isabella Novik (Seattle), and Günter M. Ziegler (Berlin). It covered a wide variety ...

    • 1803 - Topology of Arrangements and Representation Stability 

      [OWR-2018-2] (2018) - (14 Jan - 20 Jan 2018)
      The workshop “Topology of arrangements and representation stability” brought together two directions of research: the topology and geometry of hyperplane, toric and elliptic arrangements, and the homological and representation ...

    • 1218 - Triangulations 

      [OWR-2012-24] (2012) - (29 Apr - 05 May 2012)
      The earliest work in topology was often based on explicit combinatorial models – usually triangulations – for the spaces being studied. Although algebraic methods in topology gradually replaced combinatorial ones in the ...

    • The Tutte Polynomial of Ideal Arrangements 

      [OWP-2018-28] Randriamaro, Hery (Mathematisches Forschungsinstitut Oberwolfach, 2018-12-21)
      The Tutte polynomial is originally a bivariate polynomial enumerating the colorings of a graph and of its dual graph. But it reveals more of the internal structure of the graph like its number of forests, of spanning ...

    • A Uniform Model for Kirillov-Reshetikhin Crystals I: Lifting the Parabolic Quantum Bruhat Graph 

      [OWP-2012-18] Lenart, Cristian; Naito, Satoshi; Sagaki, Daisuke; Schilling, Anne; Shimozono, Mark (Mathematisches Forschungsinstitut Oberwolfach, 2012)
      We consider two lifts of the parabolic quantum Bruhat graph, one into the Bruhat order in the affine Weyl group and the other into a level-zero weight poset first considered by Littelmann. The lift into the affine Weyl ...