A combination theorem for Veech subgroups of the mapping class group,  with A. W. Reid
 

abstract
 

We prove a combination theorem for Veech subgroups of the mapping class group analogous to the first Maskit combination theorem for Kleinian groups in which the amalgamating subgroup is of parabolic type.  As a corollary, we construct subgroups of the mapping class group (for all genus at least 2), which are isomorphic to non-abelian surface groups in which all but one conjugacy class of elements (up to powers) is pseudo-Anosov.
 

    Slides from a talk at the Conference on Combinatorial Topology in Mapping Class Groups.   These slides contain only a special case of the main combination theorem which we prove.  A more general version appears in the paper.