Let G be a group. A subgroup H of G is a Cartan subgroup ofG if H is a maximal nilpotent subgroup of G, and for every normal finiteindex subgroup X of H, X has finite index in its normalizer in G.We consider Cartan subgroups of definably connect groups definable inan o-minimal structure. In we proved that, in this context,Cartan subgroups of G exist, they are definable and they fall infinitely many conjugacy classes.In this talk I will prove that the union of the Cartan subgroups isdense in the group, […]