Browsing 2019 by Issue Date

Now showing items 21-26 of 26

    • A Cheeger Type Inequality in Finite Cayley Sum Graphs 

      [OWP-2019-21] Biswas, Arindam; Saha, Jyoti Prakash (Mathematisches Forschungsinstitut Oberwolfach, 2019-07-31) - (5 May - 27 July 2019)
      Let $G$ be a finite group and $S$ be a symmetric generating set of $G$ with $|S| = d$. We show that if the undirected Cayley sum graph $C_{\Sigma}(G,S)$ is an expander graph and is non-bipartite, then the spectrum of its ...

    • Group-Graded Rings Satisfying the Strong Rank Condition 

      [OWP-2019-22] Kropholler, Peter H.; Lorensen, Karl (Mathematisches Forschungsinstitut Oberwolfach, 2019-08-16)
      A ring $R$ satisfies the $\textit{strong rank condition}$ (SRC) if, for every natural number $n$, the free $R$-submodules of $R^n$ all have rank $\leq n$. Let $G$ be a group and $R$ a ring strongly graded by $G$ such that ...

    • Groups with Spanier-Whitehead Duality 

      [OWP-2019-23] Nishikawa, Shintaro; Proietti, Valerio (Mathematisches Forschungsinstitut Oberwolfach, 2019-09-17)
      We introduce the notion of Spanier-Whitehead $K$-duality for a discrete group $G$, defined as duality in the KK-category between two $C*$-algebras which are naturally attached to the group, namely the reduced group ...

    • 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 ...

    • 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 ...

    • Global Solutions to Stochastic Wave Equations with Superlinear Coefficients 

      [OWP-2019-26] Millet, Annie; Sanz-Solé, Marta (Mathematisches Forschungsinstitut Oberwolfach, 2019-11-13)
      We prove existence and uniqueness of a random field solution $(u(t,x);(t,x)\in [0,T]\times \mathbb{R}^d)$ to a stochastic wave equation in dimensions $d=1,2,3$ with diffusion and drift coefficients of the form $|x| ...