From a result of Baumslag , if G and H are finite groups, then the amalgamated free product [G.sub.*A] H contains a free subgroup of finite index.
The free product Z/pZ * Z/qZ has a finite index free subgroup F over which the central extension splits.
The authors cover hyperbolic spaces and group actions, relative presentations and isoperimetric functions, isolated components in geodesic polygons, rotating families and windmills, hyperbolic cone-off, WPD elements and elementary subgroups, hyperbolically embedded virtually free subgroups
, rotating families from small cancellation subgroups, Dhen filling, diagram surgery, largeness properties, and a wide variety of other related subjects and topic areas.