First of all, this is not

a linear programming any more.
In general, you cannot transform a function of absolute values of linear combinations of variable into pure linear problems.

Second, in particular for this problem, it is extremely simple, you do not even need any "programming" to solve it.
Condition 2 - condition 1 tells you:
2x + z - (x+y) >= 3-1=2. Or x+z-y>=2
Therefore:
|x| + |y|+|z| >= |x -y+z| >=2.
When x=1.5, y=-.5, z=0, it reaches 2.

所有跟帖： 

• Any proof of your statement? -我还是有点不死心- ♀ (76 bytes) () 06/08/2004 postreply 16:55:07

• disagree! -sean9991- ♀ (271 bytes) () 06/09/2004 postreply 09:20:15