Largeness of LERF and 1-relator groups

Jack Button
2010 Groups, Geometry, and Dynamics  
We consider largeness of groups given by a presentation of deficiency 1, where the group is respectively free-by-cyclic, LERF or 1-relator. We give the first examples of (finitely generated free)-by-Z word hyperbolic groups which are large, show that a LERF deficiency 1 group with first Betti number at least two is large or Z Z and show that 2-generator 1-relator groups where the relator has height 1 obey the dichotomy that either the group is large or all its finite images are metacyclic. Mathematics Subject Classification (2010). 20F05.
doi:10.4171/ggd/102 fatcat:2p3yzdi5qrctngrfq7cpxm4jie