• Matchings and Squarefree Powers of Edge Ideals 

      [OWP-2019-25] Erey, Nursel; Herzog, Jürgen; Hibi, Takayuki; Saeedi Madani, Sara (Mathematisches Forschungsinstitut Oberwolfach, 2019-11-11)
      Squarefree powers of edge ideals are intimately related to matchings of the underlying graph. In this paper we give bounds for the regularity of squarefree powers of edge ideals, and we consider the question of when such ...
    • Minimal Codimension One Foliation of a Symmetric Space by Damek-Ricci Spaces 

      [OWP-2019-11] Knieper, Gerhard; Parker, John R.; Peyerimhoff, Norbert (Mathematisches Forschungsinstitut Oberwolfach, 2019-05-07)
      In this article we consider solvable hypersurfaces of the form $N \exp(\mathbb{R} H)$ with induced metrics in the symmetric space $M = SL(3,\mathbb{C})/SU(3)$, where $H$ a suitable unit length vector in the subgroup $A$ ...
    • On a Cheeger Type Inequality in Cayley Graphs of Finite Groups 

      [OWP-2019-20] Biswas, Arindam (Mathematisches Forschungsinstitut Oberwolfach, 2019-07-22) - (7 July - 7 October 2017)
      Let $G$ be a finite group. It was remarked by Breuillard-Green-Guralnick-Tao that if the Cayley graph $C(G,S)$ is an expander graph and is non-bipartite then the spectrum of the adjacency operator $T$ is bounded away from ...
    • On a Group Functor Describing Invariants of Algebraic Surfaces 

      [OWP-2019-08] Dietrich, Heiko; Moravec, Primož (Mathematisches Forschungsinstitut Oberwolfach, 2019-03-01)
      Liedtke (2008) has introduced group functors $K$ and $\tilde K$, which are used in the context of describing certain invariants for complex algebraic surfaces. He proved that these functors are connected to the theory of ...
    • On Co-Minimal Pairs in Abelian Groups 

      [OWP-2019-19] Biswas, Arindam; Saha, Jyoti Prakash (Mathematisches Forschungsinstitut Oberwolfach, 2019-07-09)
      A pair of non-empty subsets $(W,W')$ in an abelian group $G$ is a complement pair if $W+W'=G$. $W'$ is said to be minimal to $W$ if $W+(W'\setminus \{w'\}) \neq G, \forall \,w'\in W'$. In general, given an arbitrary subset ...
    • On Residuals of Finite Groups 

      [OWP-2019-17] Aivazidis, Stefanos; Müller, Thomas (Mathematisches Forschungsinstitut Oberwolfach, 2019-05-28)
      A theorem of Dolfi, Herzog, Kaplan, and Lev [DHKL07, Thm. C] asserts that in a finite group with trivial Fitting subgroup, the size of the soluble residual of the group is bounded from below by a certain power of the group ...
    • On the Lie Algebra Structure of $HH^1(A)$ of a Finite-Dimensional Algebra A 

      [OWP-2019-10] Linckelmann, Markus; Rubio y Degrassi, Lleonard (Mathematisches Forschungsinstitut Oberwolfach, 2019-04-17)
      Let $A$ be a split finite-dimensional associative unital algebra over a field. The first main result of this note shows that if the Ext-quiver of $A$ is a simple directed graph, then $HH^1(A)$ is a solvable Lie algebra. ...
    • A Quantitative Analysis of the “Lion-Man” Game 

      [OWP-2019-18] Kohlenbach, Ulrich; López-Acedo, Genaro; Nicolae, Adriana (Mathematisches Forschungsinstitut Oberwolfach, 2019-07-08)
      In this paper we analyze, based on an interplay between ideas and techniques from logic and geometric analysis, a pursuit-evasion game. More precisely, we focus on a discrete lion and man game with an $\varepsilon$-capture ...
    • Reflective Prolate-Spheroidal Operators and the KP/KdV Equations 

      [OWP-2019-24] Casper, W. Riley; Grünbaum, F. A.; Yakimov, Milen; Zurrián, Ignacio Nahuel (Mathematisches Forschungsinstitut Oberwolfach, 2019-11-05)
      Commuting integral and differential operators connect the topics of Signal Processing, Random Matrix Theory, and Integrable Systems. Previously, the construction of such pairs was based on direct calculation and ...
    • Time Discretization Schemes for Hyperbolic Systems on Networks by ε-Expansion 

      [OWP-2019-03] Altmann, Robert; Zimmer, Christoph (Mathematisches Forschungsinstitut Oberwolfach, 2019-02-12)
      We consider partial differential equations on networks with a small parameter $\epsilon$, which are hyperbolic for $\epsilon>0$ and parabolic for $\epsilon=0$. With a combination of an $\epsilon$-expansion and Runge-Kutta ...
    • Weighted Surface Algebras: General Version 

      [OWP-2019-07] Erdmann, Karin; Skowroński, Andrzej (Mathematisches Forschungsinstitut Oberwolfach, 2019-02-28)
      We introduce general weighted surface algebras of triangulated surfaces with arbitrarily oriented triangles and describe their basic properties. In particular, we prove that all these algebras, except the singular disc, ...