I am working on a Benders Decomposition, and I would like to add feasiblity cuts to master problem by Farkas dual. I have several problems as:
1. The value returned by the call of farkas dual isn't the extreme ray of the dual problem of the sub-problem?
2. The primal sub-problem is minimziation. The right hand of the sub-problem is "(B - Dy)" . I added " 0 >= r * (B-Dy)" to the master probelm, where "r" is obtained by fakas dual. But I cannot get the right solution. When I added " 0 >= (-1) * r * (B-Dy)", then the solution is right. Do you konw the reason for this?
3. Sometimes the result of r * (B-Dy) is negative, sometimes it's positive? what's the reason for this?
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