I am trying to solve a Optimization problem, but having difficulty in building a complex constraint. I am trying to assign "House" (p0-p9) to "Stores". The usual constraint of Assignment problem remains the same.       num n = 10;       set NSET = {1..n};       num d {NSET, NSET};        /* Distance Matrix */       num t {NSET, NSET};          /* Price Matrix */       min z = sum{i in NSET, j in NSET} d[i,j] * x[i,j];        /* Minimize overall distance */       con assign_i{i in NSET}: sum{j in NSET} x[i,j] = 1;       con assign_j{j in NSET}: sum{i in NSET} x[i,j] = 1; in addition I want to place a constraint based on Price. Its going to be standard deviation of PRICE of house-store pair to be less than a threshold (0.2) I have attached an excel sheet with Distance table and Price Table. Let me know if you need further clarifications. ... View more