! Keywords: Advanced Math / Ordinal Regression / Regression / Statistics;
MIN  Z1 +  Z2 +  Z3 +  Z4 +  Z5 +  Z6 +  Z7 +  Z8
SUBJECT TO
 2)  Z1 + 4 X1 - 4 Y1 + 1.2 X2 - 1.2 Y2 + 2.5 X3 - 2.5 Y3 - 5 X4
     + 5 Y4  >= 0
 3)  Z2 +  X1 -  Y1 + 0.1 X2 - 0.1 Y2 +  X3 -  Y3  -  X4  
     -  Y4  >=  0
 4)  Z3 + 3 X1 - 3 Y1 + 1.4 X2 - 1.4 Y2 + 2 X3 - 2 Y3 - 4 X4
     + 4 Y4  >=  0
 5)  Z4 -  X1 +  Y1 + 0.2 X2 - 0.2 Y2 - 0.5 X3 + 0.5 X3 +  X4
     -  Y4  >=  0
 6)  Z5 - 2 X1 + 2 Y1 - 1.2 X2 + 1.2 Y2 - 1.5 X3 + 1.5 Y3 + 3 X4
     - 3 Y4  >=  0
 7)  Z6 - 2 X1 + 2 Y1 - 0.3 X2 + 0.3 Y2 - 1.5 X3 + 1.5 Y3 + 2 X4
     - 2 Y4  >=  0
 8)  Z7 - 2 X1 + 2 Y1 - 0.9 X2 + 0.9 Y2 -  X3 +  Y3 + 3 X4
     - 3 Y4  >=  0
 9)  Z8 -  X1 +  Y1 - 1.1 X2 + 1.1 Y2 - 0.5 X3 + 0.5 Y3 + 2 X4
     - 2 Y4  >=  0
10)  - 0.6 X2 + 0.6 Y2 + 0.5 X3 - 0.5 Y3 + 3 X4 - 3 Y4 =  1
END