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Solution and incumbent are different #208

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SupplyChef opened this issue Mar 22, 2024 · 2 comments
Closed

Solution and incumbent are different #208

SupplyChef opened this issue Mar 22, 2024 · 2 comments

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@SupplyChef
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Hello,

I am seeing a bit of a strange behavior. I have a MIP problem. It solves fine as seen in the log. The incumbent objective (maximization) is around 16856993205.89 at the time limit. But when the final results are reported the objective is very different. Am I misunderstanding the logs?

At the moment I only see this on a very big model. Not sure how to provide a model to repro.

Thanks.

Logs:
...
L 880 830 3 0.00% 21322168436.27 16856993205.89 26.49% 10690 1724 111 1644k 1767.3s
1019 969 4 0.00% 21322168436.27 16856993205.89 26.49% 10690 1724 118 1890k 3782.4s

Solving report
Status Time limit reached
Primal bound 16856993205.9
Dual bound 21322168436.3
Gap 26.49% (tolerance: 0.01%)
Solution status feasible
-19188000000 (objective)
0 (bound viol.)
0 (int. viol.)
0 (row viol.)
Timing 3782.37 (total)
1.28 (presolve)
0.00 (postsolve)
Nodes 1019
LP iterations 1890255 (total)
635988 (strong br.)
44157 (separation)
186341 (heuristics)

@odow
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odow commented Mar 23, 2024

But when the final results are reported the objective is very different.

What is the output of JuMP.solution_summary(model) after solving?

What is the value of JuMP.objective_value(model)?

It solves fine as seen in the log

It stopped due to a time limit?

@SupplyChef
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I am having difficulties reproducing the problem reliably. I believe it occurs when the problem is badly scaled. I think you can close this issue and I can re-open if I find a reliable repro. Thanks.

@odow odow closed this as completed Apr 11, 2024
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