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<p>Hello, <br>
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<p>I'm solving a NLP Problem with couenne. My model is written in Python and Pyomo.<br>
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<p>In my case, Couenne takes very long without exiting with an optimal solution. The best solution is given after a few iterations and doesn't change after hours of execution:</p>
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<p><span style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);">Cbc0010I After 7100 nodes, 3364 on tree, </span><span style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px; background-color: rgb(255, 255, 0);">0.25239475
best solution</span><span style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);">, best possible 0.15 (14.72 seconds)</span><br>
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<p>Therefore, I've set the option time_limit to a smaller value (100 seconds), to be able to retrieve the best solution found so far and print it to a file. <span style="font-size: 12pt;">However couenne prints another solution than the on</span><span style="font-size: 12pt;">e
stated in the solver log:</span></p>
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<p><span style="font-size: 12pt;">instead of 0.25239475, I get </span><span style="font-size: 12pt;">0.281323177 <span style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; background-color: rgb(255, 255, 255);">as a value for the objective
function.</span></span></p>
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<p><span style="font-size: 12pt;"><span style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);">The value printed by Couenne is the same one I get</span><span style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);"> if
I solve my model using Ipopt.</span><br>
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<p><span style="font-size: 12pt;">1) Do you have any idea, why this occurs? Is it possible that Couenne is printing the best solution found by ipopt, since it's used in Couenne?</span></p>
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<p><span style="font-size: 12pt;">2) Is there a way to obtain the better solution given in the solver log? </span></p>
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<p>I look forward to your reply. <br>
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<p>Best,<br>
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<p>Nesrine <br>
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