Ergodic Theory and Dynamical Systems

The forcing partial order on the three times punctured disk

a1 Department of Mathematics and Science, Lehman College, CUNY, Bedford Park Boulevard, Bronx, NY 10468-1589, USA


The two-dimensional analogue of the Sharkovski order on periods for maps of the interval restricts to a partial order on essential pseudo-Anosov conjugacy classes in the mapping class group of the $n$-times punctured disk. In this paper we give an explicit description of this restricted partial order in the case when $n=3$.

(Received February 24 1995)
(Revised April 29 1996)