In the case of printers, the degree of difference in the printer parameter may be determined as ???0??? if nodes X and Y are both provided with a printer and their printers are of the same type, as ???1??? if they are provided with a printer but their types and specifications are different, and as ???2??? if node X uses a printer but node Y does not. gi (i=1, 2, . . . , t) is a weighting variable.