In fact, there are some very old books that show this as the average, the sum divided by two arithmetic mean, but the modern practice is to use the geometric mean.
Production possibility set in DEA has two equivalent forms: sum form and intersection form. In comparison, the later one has more geometric visualization and convenience of calculation.
DEA的生产可能集有两种等价形式—和形式及交形式。相比较而言，交形式更具几何直观性及计算便利性。
3
Evaluate the partition function as and check that the result agrees with the standard geometric series sum.