2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/120725There exists a (relatively minimal) genus g Lefschetz fibration with only one singular fiber over a closed (Riemann) surface of genus h iff g>2 and h>1. The singular fiber can be chosen to be reducible or irreducible. Other results are that every Dehn twist on a closed surface of genus at least three is a product of two commutators and no Dehn twist on any closed surface is equal to a single commutator.6 pages, 2 figures, second versionGeometric TopologySymplectic Geometry57M99(20F38)text