RS01221: CPLEX CAN CLAIM OPTIMALITY ON AN INFEASIBLE NETWORK WITH A SUPPLY/DEMAND IMBALANCE AND NEGATIVE FLOW AT THE ROOT NODE
Closed as fixed if next.
If a network has a supply/demand imbalance that forces flow into the root node (i.e. the first node specified in the input), CPLEX will declare optimality even though the solution is obviously infeasible. For example, the network MINIMIZE NETWORK netex1 SUPPLY n1 : 1 n4 : -5 ARCS a1 : n1 -> n4 OBJECTIVE a1 : 3 BOUNDS 0 <= a1 <= 25 ENDNETWORK Results in CPLEX> r bad.net Problem 'bad.net' read. Read time = 0.00 sec. CPLEX> net Iteration log . . . Iteration: 0 Infeasibility = 5.000000 (5) Network - Optimal: Objective = 1.5000000000e+01 Solution time = 0.00 sec. Iterations = 1 (1) This exists for versions 10.0 - 12.5. It has been fixed in 188.8.131.52. No workaround available. This will typically only happen on tiny networks like the one above where there is no flexibility regarding the flows resulting from the imbalance. Keeping call open for now until additional info regarding the network configurations that cause this bug to bite is available.
No workaround available; see problem description for more details.
Some networks with obvious supply/demand imbalances may result in an incorrect claim of optimality.
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APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
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