Now showing items 31-40 of 40

    • Poincaré families of G-bundles on a curve (Pre-published version) 

      Hoffmann, Norbert; Biswas, Indranil (Springer Verlag, 2012)
      Let G be a reductive group over an algebraically closed field k. Consider the moduli space of stable principal G-bundles on a smooth projective curve C over k. We give necessary and sufficient conditions for the existence of ...
    • Rationality and Poincaré families for vector bundles with extra structure on a curve (Pre-published version) 

      Hoffmann, Norbert (Oxford University Press, 2007)
      Iterated Grassmannian bundles over moduli stacks of vector bundles on a curve are shown to be birational to an affine space times a moduli stack of degree 0 vector bundles, following the method of King and Schofield. ...
    • Response surface designs using the generalized variance inflation factors 

      O'Driscoll, Diarmuid; Ramirez, Donald E. (Cogent OA, 2015)
      We study response surface designs using the generalized variance inflation factors for subsets as an extension of the variance inflation factors.
    • Solving cubic equations in two variables 

      Kreussler, Bernd (Irish Mathematical Society, 2007)
      After recalling a geometric construction of all Pythagorean triples of integers, the same idea is applied to find rational solutions of cubic equations in two variables. This leads to the definition of the Mordell-Weil ...
    • Some moduli stacks of symplectic bundles on a curve are rational (Pre-published version) 

      Biswas, Indranil; Hoffmann, Norbert (Elsevier, 2008)
      Let C be a smooth projective curve of genus g ≥ 2 over a field k. Given a line bundle L on C, let Sympl2n,L be the moduli stack of vector bundles E of rank 2n on C endowed with a nowhere degenerate symplectic form b : E ⊗ ...
    • Stability of Arakelov bundles and tensor products without global sections 

      Hoffmann, Norbert (Documenta Mathematica, 2003)
      This paper deals with Arakelov vector bundles over an arithmetic curve, i.e. over the set of places of a number field. The main result is that for each semistable bundle E, there is a bundle F such that E⊗F has at least ...
    • SU(5) heterotic standard model bundles (Pre-published version) 

      Hoffmann, Norbert; Andreas, Björn (Springer Verlag, 2012)
      We construct a class of stable SU(5) bundles on an elliptically fibered Calabi-Yau threefold with two sections, a variant of the ordinary Weierstrass fibration, which admits a free involution. The bundles are invariant under ...
    • Torelli theorem for the Deligne-Hitchin moduli space (Pre-published version) 

      Biswas, Indranil; Gómez, Tomás L.; Hoffmann, Norbert; Logares, Marina (Springer Verlag, 2009)
      Fix integers g ≥ 3 and r ≥ 2, with r ≥ 3 if g = 3. Given a compact connected Riemann surface X of genus g, let M DH (X) denote the corresponding SL(r,C) Deligne–Hitchin moduli space. We prove that the complex analytic ...
    • Trace forms of symbol algebras (Pre-published version) 

      Flatley, Ronan (World Scientific Publishing Complany, 2012)
      Let S be a symbol algebra. The trace form of S is computed and it is shown how this form can be used to determine whether S is a division algebra or not. In addition, the exterior powers of the trace form of S are computed.
    • Twistor spaces with a pencil of fundamental divisors 

      Kreussler, Bernd (Documenta Mathematica, 1999)
      In this paper simply connected twistor spaces Z containing a pencil of fundamental divisors are studied. The Riemannian base for such spaces is diffeomorphic to the connected sum nCP2 . We obtain for n 5 a complete ...