Dear sir/madam: I am a research fellow in National University of Singapore and wrote a Benders Decomposition program using ECLiPSe 5.5 on Windows 2000 professional. My program always appear Illeagal Opearion showing dialog. I found this is because there is something wrong with eplex instance. My program includes one master problem eplex instance and one sub problem eplex instance. Each time master problem is solved, its variables' value is transfered to sub problem. The sub problem give benders cut to master problem after solved. I at first setup master problem using "mastpro:eplex_solver_setup(min(Z0),_,[],0,[new_constraint,bounds])", and add cut to it using "mastpro:(...)". My program can run well using simple data, but failed using complex data with the same model. So I don't know such a eplex update method is wrong or this is a debug. I attached my model to this email. You can test it, type "solve(1,Cost,Vars)" to get the standad MILP result and type "solve_bender(1,Vars)" to run benders decomposition algorithm. Also you can change the parameter "1" to "2" to run the same model with a more complex data. The running result consist of each iteration's result, means [iteration no, low bound, upper bound]. Many thanks, tian wende <<bender5.ecl>>
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