2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/221825We calculate the monodromies of the canonical Lefschetz pencils on a pair of homeomorphic Horikawa surfaces. We show in particular that the (pluri)canonical pencils on these surfaces have the same monodromy groups, and are related by a "partial twisting" operation.This is the version published by Geometry & Topology on 29 November 2006Geometric TopologySymplectic Geometry57R17, 14D05, 53D35text