Riccardo Pedrotti (UMass) : An obstruction to the existence of sections for a Lefschetz fibration

Please note this event occurred in the past.
September 18, 2026 2:30 pm - 3:30 pm ET
Seminars,
5 College Geometry and Topology Seminar
Riccardo Pedrotti
LGRT 1681

An obstruction to the existence of sections for a Lefschetz fibration

Abstract: We characterise the presence of a section for a Lefschetz fibration over the sphere in terms of vanishing of an obstruction class living in a quotient of the fundamental group of the regular fiber. In the case of transitive LF we prove that such obstruction class always vanishes, therefore detecting a smooth section. Time permitting we will also show a computation of this obstruction class to the MCK fibration.