Model hs76 Variables x[1:4] = 0.5, >=0 obj End Variables Equations x[1] + 2*x[2] + x[3] + x[4] <= 5 3*x[1] + x[2] + 2*x[3] - x[4] <= 4 x[2] + 4*x[3] >= 1.5 ! best known objective = -4.681818181 obj = x[1]^2 + 0.5*x[2]^2 + x[3]^2 + 0.5*x[4]^2 - x[1]*x[3] + x[3]*x[4] - x[1] - 3*x[2] + x[3] - x[4] End Equations End Model