A characterisation of virtually free groups
Gilman R.H., Hermiller S., Holt D.F.
We prove that a finitely generated group G is virtually free if and only if there exists a generating set for G and к > 0 such that all k-locally geodesic words with respect to that generating set are geodesic.
Ссылка удалена правообладателем
----
The book removed at the request of the copyright holder.