Modified Xiao conjecture for the relative irregularity
Modified Xiao conjecture for the relative irregularity
Let be a fibred surface, meaning a fibration from a smooth projective surface to a smooth projective curve , with general fibre of genus . Write for the relative irregularity and call non-isotrivial when its smooth fibres are not all mutually isomorphic. Modified Xiao conjecture. For every non-isotrivial fibred surface of genus , one has
This modifies Xiao's original bound, which was disproved by Pirola and by later examples of Albano and Pirola. The supplied status evidence records that the modified inequality is also contradicted by those counterexamples, although they satisfy equality for the modified bound.
Sources & referencesView supporting material
Primary source
Vìctor González-Alonso, Lidia Stoppino and Sara Torelli, “On the rank of the flat unitary summand of the Hodge bundle”, arXiv:1709.05670 (2018).
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