For an arbitrary finitely generated Abelian Group , the rank of is defined to be the rank of the Free generating Subset modulo its Torsion Subgroup. For a finitely generated Group, the rank is defined to be the rank of its ``Abelianization.''
See also Abelian Group, Betti Number, Burnside Problem, Quasithin Theorem, Quasi-Unipotent Group, Torsion (Group Theory)