GREENBERGS THEOREM FOR QUASI-CONVEX SUBGROUPS OF WORD HYPERBOLIC GROUPS

Analogues of a theorem of Greenberg about finitely generated subgroups of free groups are proved for quasiconvex subgroups of word hyperboli c groups. It is shown that a quasiconvex subgroup of a word hyperbolic group is a finite index subgroup of only finitely many other subgroup s.