the National Natural Science Foundation of China (No. 10571080); the Natural Science Foundation of Jiangxi Province (No. 0611042); the Science and Technology Projiet Foundation of Jiangxi Province (No. G[20061194) and the Doctor Foundation of Jiangxi University of Science and Technology.
A ring R is called orthogonal if for any two idempotents e and f in R, the condition that e and f are orthogonal in R implies the condition that [eR] and [fR] are orthogonal in K0(R)+, i.e., [eR]∧[fR] = 0. In this pa...