Originally posted by: Taroon

Hi!

I am trying to model hub-arc location problem on cplex. I would like to know which nodes will be the gateways and the fractional demand for each arc that is activated. In other words, those are the decision variables.

The network is directed and in a hierarchical structure. the origins are only nodes in O, the destinations are only nodes in D, the candidates for gateways (G) are a subset of O, therefore, could be origin nodes as well, and the hubs (H) are a subset of D and therefore could be destination nodes.

I tried to design the network into the cplex with the objective of minimizing cost, and several constraints. However, I come up with no solution. moreover, I am quite confused with executing the results at the end of the model.

I would like to ask for any bits of advice that can help the model to be able to result in solutions! I attached files .mod and .dat as well.

Thanks!!

Originally posted by: T_O

I did not look at the details, but the conflict refiner yields 2 contradictory constraints:

X#32#27 + X#33#27 + X#34#27 + X#35#27 + X#36#27 + X#37#27 + X#38#27 + X#39#27 + X#40#27 + X#41#27 + X#42#27 + X#43#27 + X#44#27 + X#45#27 + X#46#27 + X#47#27  = 19

X#32#27 + X#33#27 + X#34#27 + X#35#27 + X#36#27 + X#37#27 + X#38#27 + X#39#27 + X#40#27 + X#41#27 + X#42#27 + X#43#27 + X#44#27 + X#45#27 + X#46#27 + X#47#27  = 0

Maybe, this already helps?

Best regards,
Thomas