• Applications of BV Type Spaces 

      [OWP-2019-04] Appell, Jürgen; Bugajewska, Daria; Kasprzak, Piotr; Merentes, Nelson; Reinwand, Simon; Sánchez, José Luis (Mathematisches Forschungsinstitut Oberwolfach, 2019-02-13)
    • The Becker-Gottlieb Transfer: a Geometric Description 

      [OWP-2019-13] Wang, Yi-Sheng (Mathematisches Forschungsinstitut Oberwolfach, 2019-05-14)
      In this note, we examine geometric aspects of the Becker-Gottlieb transfer in terms of the Umkehr and index maps, and rework some classic index theorems, using the cohomological formulae of the Becker-Gottlieb transfer. ...
    • Cataland: Why the Fuß? 

      [OWP-2019-01] Stump, Christian; Thomas, Hugh; Williams, Nathan (Mathematisches Forschungsinstitut Oberwolfach, 2019-01-21)
      The three main objects in noncrossing Catalan combinatorics associated to a finite Coxeter system are noncrossing partitions, clusters, and sortable elements. The first two of these have known Fuß-Catalan generalizations. ...
    • 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 ...
    • Chirality of Real Non-Singular Cubic Fourfolds and Their Pure Deformation Classification 

      [OWP-2019-14] Finashin, Sergey; Kharlamov, Viatcheslav (Mathematisches Forschungsinstitut Oberwolfach, 2019-05-15)
      In our previous works we have classified real non-singular cubic hypersurfaces in the 5-dimensional projective space up to equivalence that includes both real projective transformations and continuous variations of ...
    • Congruences Associated with Families of Nilpotent Subgroups and a Theorem of Hirsch 

      [OWP-2019-16] Aivazidis, Stefanos; Müller, Thomas (Mathematisches Forschungsinstitut Oberwolfach, 2019-05-27)
      Our main result associates a family of congruences with each suitable system of nilpotent subgroups of a finite group. Using this result, we complete and correct the proof of a theorem of Hirsch concerning the class number ...
    • Experimenting with Symplectic Hypergeometric Monodromy Groups 

      [OWP-2019-15] Detinko, Alla; Flannery, Dane; Hulpke, Alexander (Mathematisches Forschungsinstitut Oberwolfach, 2019-05-22)
      We present new computational results for symplectic monodromy groups of hypergeometric differential equations. In particular, we compute the arithmetic closure of each group, sometimes justifying arithmeticity. The results ...
    • The First Hochschild Cohomology as a Lie Algebra 

      [OWP-2019-09] Rubio y Degrassi, Lleonard; Schroll, Sibylle; Solotar, Andrea (Mathematisches Forschungsinstitut Oberwolfach, 2019-04-16)
      In this paper we study sufficient conditions for the solvability of the first Hochschild cohomology of a finite dimensional algebra as a Lie algebra in terms of its Ext-quiver in arbitrary characteristic. In particular, ...
    • The Fourier Transform on Harmonic Manifolds of Purely Exponential Volume Growth 

      [OWP-2019-12] Biswas, Kingshook; Knieper, Gerhard; Peyerimhoff, Norbert (Mathematisches Forschungsinstitut Oberwolfach, 2019-05-08)
      Let $X$ be a complete, simply connected harmonic manifold of purely exponential volume growth. This class contains all non-flat harmonic manifolds of non-positive curvature and, in particular all known examples of harmonic ...
    • A Function Algebra Providing New Mergelyan Type Theorems in Several Complex Variables 

      [OWP-2019-02] Falcó, Javier; Gauthier, Paul Montpetit; Manolaki, Myrto; Nestoridis, Vassili (Mathematisches Forschungsinstitut Oberwolfach, 2019-02-11)
      For compact sets $K\subset \mathbb C^{d}$, we introduce a subalgebra $A_{D}(K)$ of $A(K)$, which allows us to obtain Mergelyan type theorems for products of planar compact sets as well as for graphs of functions.
    • Group Algebras of Compact Groups. A New Way of Producing Group Hopf Algebras over Real and Complex Fields: Weakly Complete Topological Vector Spaces 

      [OWP-2019-06] Hofmann, Karl Heinrich; Kramer, Linus (Mathematisches Forschungsinstitut Oberwolfach, 2019-02-27)
      Weakly complete real or complex associative algebras $A$ are necessarily projective limits of finite dimensional algebras. Their group of units $A^{-1}$ is a pro-Lie group with the associated topological Lie algebra $A_{\rm ...
    • Hölder Continuity of the Spectra for Aperiodic Hamiltonians 

      [OWP-2019-05] Beckus, Siegfried; Bellissard, Jean; Cornean, Horia (Mathematisches Forschungsinstitut Oberwolfach, 2019-02-26)
      We study the spectral location of a strongly pattern equivariant Hamiltonians arising through configurations on a colored lattice. Roughly speaking, two configurations are "close to each other" if, up to a translation, ...
    • 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 ...
    • 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 ...