GAMS World Forum

Hello ! could anybody help me by modeling constraints Nr.4 on the screenshot in the Attachment. M is a subset of N and there are always 2^n subsets of a set N. As example if i have N with 3 Cities {1,2,3} than there are M = 2^3 = 8 different M: M1 = {1}, M2 = {2}, M3 = {3}, M4 = {1,2}, M5 = {1,3}, M...