Browsing 1 - Oberwolfach Preprints (OWP) by MSC "55"

Now showing items 1-12 of 12

    • Aeppli-Bott-Chern-Massey Products, Bigraded Notions of Formality, and Non-Zero Degree Maps 

      [OWP-2022-04] Milivojević, Aleksandar; Stelzig, Jonas (Mathematisches Forschungsinstitut Oberwolfach, 2022-02-15)
      We introduce and study notions of bigraded formality for the algebra of forms on a complex manifold, along with their relation to higher Aeppli-Bott-Chern-Massey products which extend, in an augmented setting, the case of ...

    • The Brown Complex in Non-Defining Characteristic and Applications 

      [OWP-2023-14] Rossi, Damiano (Mathematisches Forschungsinstitut Oberwolfach, 2023-07-25)
      We study the Brown complex associated to the poset of $\ell$-subgroups in the case of a finite reductive group defined over a field $\mathbb{F}_q$ of characteristic prime to $\ell$. First, under suitable hypotheses, we ...

    • Definable orthogonality classes in accessible categories are small 

      [OWP-2011-14] Bagaria, Joan; Casacuberta, Carles; Mathias, Adrian R. D.; Rosický, Jiří (Mathematisches Forschungsinstitut Oberwolfach, 2011-05-15)
      We lower substantially the strength of the assumptions needed for the validity of certain results in category theory and homotopy theory which were known to follow from Vopenka's principle. We prove that the necessary ...

    • Embedding Spaces of Split Links 

      [OWP-2022-13] Boyd, Rachael; Bregman, Corey (Mathematisches Forschungsinstitut Oberwolfach, 2022-08-01)
      We study the homotopy type of the space $\mathcal{E}(L)$ of unparametrised embeddings of a split link $L=L_1\sqcup \ldots \sqcup L_n$ in $\mathbb{R}^3$. Inspired by work of Brendle and Hatcher, we introduce a semi-simplicial ...

    • 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 ...

    • Hight functions on quaternionic Stiefel manifolds 

      [OWP-2015-10] Macías-Virgós, Enrique; Strom, Jeffrey; Tanré, Daniel; Oprea, John (Mathematisches Forschungsinstitut Oberwolfach, 2015-07-29)
      In this note, we study height functions on quaternionic Stiefel manifolds and prove that all these height functions are Morse-Bott. Among them, we characterize the Morse functions and give a lower bound for their number ...

    • Lifting Spectral Triples to Noncommutative Principal Bundles 

      [OWP-2021-02] Schwieger, Kay; Wagner, Stefan (Mathematisches Forschungsinstitut Oberwolfach, 2021-01-11)
      Given a free action of a compact Lie group $G$ on a unital C*-algebra $\mathcal{A}$ and a spectral triple on the corresponding fixed point algebra $\mathcal{A}^G$, we present a systematic and in-depth construction of ...

    • Milnor fibre homology via deformation 

      [OWP-2015-22] Siersma, Dirk; Tibăr, Mihai-Marius (Mathematisches Forschungsinstitut Oberwolfach, 2015)
      In case of one-dimensional singular locus, we use deformations in order toget refined information about the Betti numbers of the Milnor fibre.

    • New representations of matroids and generalizations 

      [OWP-2011-18] Izhakian, Zur; Rhodes, John L. (Mathematisches Forschungsinstitut Oberwolfach, 2011)
      We extend the notion of matroid representations by matrices over fields by considering new representations of matroids by matrices over finite semirings, more precisely over the boolean and the superboolean semirings. This ...

    • 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 ...

    • Realizing Spaces as Classifying Spaces 

      [OWP-2015-01] Lupton, Gregory; Smith, Samuel Bruce (Mathematisches Forschungsinstitut Oberwolfach, 2015-04-10)
      Which spaces occur as a classifying space for fibrations with a given fibre? We address this question in the context of rational homotopy theory. We construct an infinite family of finite complexes realized (up to rational ...

    • The Simplicial Complex of Brauer Pairs of a Finite Reductive Group 

      [OWP-2023-12] Rossi, Damiano (Mathematisches Forschungsinstitut Oberwolfach, 2023-07-17)
      In this paper we study the simplicial complex induced by the poset of Brauer pairs ordered by inclusion for the family of finite reductive groups. In the defining characteristic case the homotopy type of this simplicial ...