Subgroup separability and 3-manifold groups
We prove a conjecture of Jaco that the peripheral subgroups of a 3- manifold group are separable. By considering an example of Burns, Karrass and Solitar we give examples of some 3-manifold groups which are amalgamated free products of Lerf 3-manifold groups but are not themselves Lerf. Using the same technique, we give the first explicit geometric examples of a Z-amalgamated free product of two Lerf groups which is not Lerf.
peripheral subgroups of a 3-manifold group
Z-amalgamated free product of two Lerf groups
scientific article; zbMATH DE number 1047
scientific article