Hy. Chen et Wt. Tong, CATEGORY XL(R) AND XL-GROUPS, Science in China. Series A, Mathematics, Physics, Astronomy & Technological Sciences, 38(2), 1995, pp. 159-170
New groups: XL-groups are constructed. These groups are easy to calcul
ateand they reflect more general properties of rings than K-0-groups.
As their applications, some characteristics of group ring with torsion
-free K-0-groups are obtained.