The slope of fibred surfaces: unitary rank and Clifford index

Abstract

We prove new slope inequalities for relatively minimal fibred surfaces, showing an influence of the relative irregularity, of the unitary rank and of the Clifford index on the slope. The argument uses Xiao's method and a new Clifford-type inequality for subcanonical systems on non-hyperelliptic curves.

23 pages, references added, final version. With respect to the published version, in the last section there is an added explanation for the computation of the gonality of the examples

References in corpus (3)

• Families of curves with Higgs field of arbitrarily large kernel
• Higher Dimensional Slope Inequalities for Irregular fibrations
• Some remarks on bielliptic and trigonal curves

Cited by in corpus (1)

• Fibred surfaces and their unitary rank