Slopes of trigonal fibred surfaces and of higher dimensional fibrations

• Miguel Ángel Barja ^[1] ; Lidia Stoppino ^[2]
  1. [1] Universitat Politècnica de Catalunya

     Universitat Politècnica de Catalunya

     Barcelona, España

     
  2. [2] Universitá dell’Insubria, Como
• Localización: Annali della Scuola Normale Superiore di Pisa. Classe di scienze, ISSN 0391-173X, Vol. 8, Nº 4, 2009, págs. 647-658
• Idioma: inglés
• DOI: 10.2422/2036-2145.2009.4.02
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• Resumen

  • We give lower bounds for the slope of higher dimensional fibrations f : X −→ B over curves under conditions of GIT-semistability of the fibres, using a generalization of a method of Cornalba and Harris. With the same method we establish a sharp lower bound for the slope of trigonal fibrations of even genus and general Maroni invariant; this result in particular proves a conjecture due to Harris and Stankova-Frenkel.