A classification of subgroups of SL(4,R)SL(4,R) isomorphic to R3R3 and generalized cusps in projective 3 manifolds

This paper uses work of Haettel to classify all subgroups of PGL4(R)PGL4(R) isomorphic to (R3,+)(R3,+), up to conjugacy. We use this to show there are 4 families of generalized cusps up to projective equivalence in dimension 3.