Tag Archives: surface subgroup

Surface subgroups of Sapir’s group

Let be the free group on two generators, and let be the endomorphism defined on generators by and . We define Sapir’s group  to be the ascending HNN extension This group was studied by Crisp-Sageev-Sapir in the context of their … Continue reading

Posted in Ergodic Theory, Groups, Surfaces | Tagged , , , , , , | 12 Comments

Polygonal words

Last Friday, Henry Wilton gave a talk at Caltech about his recent joint work with Sang-hyun Kim on polygonal words in free groups. Their work is motivated by the following well-known question of Gromov: Question(Gromov): Let be a one-ended word-hyperbolic group. … Continue reading

Posted in Groups, Surfaces | Tagged , , , , , , , , | 6 Comments