We 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.
Received: 28 May 2006
Revised: 25 September 2006
Accepted: 22 October 2006
Published: 29 November 2006
Proposed: Rob Kirby
Seconded: Ronald Fintushel, Ronald Stern