preprint-author: 
A. de Carvalho and M. Paternain
preprint-title: 
Monotone quotients of surface diffeomorphisms
preprint-abstract: 

A homeomorphism of a compact metric space is tight provided every non-degenerate compact connected (not necessarily invariant) subset carries positive entropy. It is shown that every $C^{1+\alpha}$ diffeomorphism of a closed surface factors to a tight homeomorphism of a generalized cactoid (roughly, a surface with nodes) by a semi-conjugacy whose fibers carry zero entropy.

preprint-year: 
2002