English

Answer to a question by Fujita on Variation of Hodge Structures

Algebraic Geometry 2013-11-14 v1 Complex Variables

Abstract

We first provide details for the proof of Fujita's second theorem for K\"ahler fibre spaces over a curve, asserting that the direct image VV of the relative dualizing sheaf splits as the direct sum V=AQ V = A \oplus Q, where AA is ample and QQ is unitary flat. Our main result then answers in the negative the question posed by Fujita whether VV is semiample. In fact, VV is semiample if and only if QQ is associated to a representation of the fundamental group of BB having finite image. Our examples are based on hypergeometric integrals.

Keywords

Cite

@article{arxiv.1311.3232,
  title  = {Answer to a question by Fujita on Variation of Hodge Structures},
  author = {Fabrizio Catanese and Michael Dettweiler},
  journal= {arXiv preprint arXiv:1311.3232},
  year   = {2013}
}

Comments

26 pages, the article is dedicated to Yujiro Kawamata on the occasion of his 60-th birthday