Princeton University Mathematics Department Colloquium | |

Topic: | Universally defined cycles |

Speaker: | Claire Voisin |

Affiliation: | Centre national de la recherche scientifique; Distinguished Visiting Professor, School of Mathematics |

Date: | Wednesday, April 15 |

Time/Room: | 4:30pm - 5:30pm/Fine 314, Princeton University |

The Franchetta conjecture (now a theorem) says basically that any line bundle on the universal family of curves of genus at least 2 restricts to a multiple of the canonical bundle on each fiber. We formulate a generalization of this statement for surfaces and provide a characterization of the Chern classes: polynomials in the Chern classes are the only "universally defined" cycles.