\ Opgave 8 (Hillier and Lieberman, exercise 13)

minimize 

  x1 + x2

subject to

\ either x1 >= 3 or x2 >= 3
\ upper bound on x1 and x2 is 9 - epsilon, 
\ since max |x1 - x2| = 6 and either x1 < 3 or x2 < 3
x1 - 3 d1 >= 0
x2 - 3 d2 >= 0
x1 - 6.01 d1 <= 2.99
x2 - 6.01 d2 <= 2.99
d1 + d2 = 1

\ at least one of constraints is satisfied
2 x1 +   x2 - 7 d3 >= 0
  x1 +   x2 - 5 d4 >= 0
  x1 + 2 x2 - 7 d5 >= 0
d3 + d4 + d5 >= 1

\ |x1 - x2| = 0,3,6
x1 - x2 + 3a = 6

\ x1 >= 0 and x2 >= 0
x1 >= 0
x2 >= 0

\ bounds on integer variables
d1 <= 1
d2 <= 1
d3 <= 1
d4 <= 1
d5 <= 1
a <= 4

binary 

d1 d2 d2 d4 d5 

general

a

end