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Hi Prof. Marco Lübbecke,
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<div>Thanks for the timely response. We are doing research on using machine learning to speed up the process of solving pricing subproblems. An attempt by us is done on the graph coloring problem [1], and we are planning to develop a more generic solution
for "unstructured" MIP inputs.</div>
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<div>GCG seems to have trouble solving "un<span style="font-family: "Segoe UI", "Segoe UI Web (West European)", "Segoe UI", -apple-system, BlinkMacSystemFont, Roboto, "Helvetica Neue", sans-serif; font-size: 12pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">structured"
MIP inputs. It raises different types of assertions errors for different instances in MIPLIB with the decomposition tags. It seems that GCG has not been tested for "unstructured" inputs. </span><span style="color: rgb(0, 0, 0); font-family: "Segoe UI", "Segoe UI Web (West European)", "Segoe UI", -apple-system, BlinkMacSystemFont, Roboto, "Helvetica Neue", sans-serif; font-size: 12pt; background-color: rgba(0, 0, 0, 0);">I
would love to fix these errors and make GCG work on these </span><span style="color: rgb(0, 0, 0); font-family: "Segoe UI", "Segoe UI Web (West European)", "Segoe UI", -apple-system, BlinkMacSystemFont, Roboto, "Helvetica Neue", sans-serif; font-size: 12pt; background-color: rgba(0, 0, 0, 0);">"unstructured"
inputs. However, after some attempts, I feel that </span><span style="color: rgb(0, 0, 0); font-family: "Segoe UI", "Segoe UI Web (West European)", "Segoe UI", -apple-system, BlinkMacSystemFont, Roboto, "Helvetica Neue", sans-serif; font-size: 12pt; background-color: rgba(0, 0, 0, 0);">debugging
GCG code by myself is challenging, as many implementation details are not documented yet. </span></div>
<div><span style="color: rgb(0, 0, 0); font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt;"><br>
</span></div>
<div><span style="color: rgb(0, 0, 0); font-family: "Segoe UI", "Segoe UI Web (West European)", "Segoe UI", -apple-system, BlinkMacSystemFont, Roboto, "Helvetica Neue", sans-serif; font-size: 12pt; background-color: rgba(0, 0, 0, 0);">Lastly, we would love
to hear <span style="background-color:rgb(255, 255, 255);display:inline !important">
from you </span>any suggestions to proceed in this direction. </span></div>
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Best regards,</div>
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Yunzhuang</div>
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[1] <span style="color:rgb(34, 34, 34);font-family:Arial, sans-serif;font-size:13px;text-align:left;background-color:rgb(255, 255, 255);display:inline !important">Shen, Yunzhuang, et al. "Enhancing Column Generation by a Machine-Learning-Based Pricing Heuristic
for Graph Coloring."<span> </span></span><i style="color:rgb(34, 34, 34);font-family:Arial, sans-serif;font-size:13px;text-align:left;background-color:rgb(255, 255, 255)">AAAI</i><span style="color:rgb(34, 34, 34);font-family:Arial, sans-serif;font-size:13px;text-align:left;background-color:rgb(255, 255, 255);display:inline !important"><span> </span>(2022).</span></div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Marco Lübbecke <marco.luebbecke@rwth-aachen.de><br>
<b>Sent:</b> Saturday, April 16, 2022 11:38 PM<br>
<b>To:</b> Yunzhuang Shen <s3640365@student.rmit.edu.au><br>
<b>Cc:</b> scip@zib.de <scip@zib.de><br>
<b>Subject:</b> Re: [SCIP] Errors in using GCG version 3.5 for solving some miplib instances.</font>
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<div class="BodyFragment"><font size="2"><span style="font-size:11pt;">
<div class="PlainText">Hi Yunzhuang,<br>
<br>
thanks, we file this as a bug report to look into as soon as we have<br>
capacities; you can write to me directly for any updates on this<br>
issue.<br>
<br>
And thanks also for trying GCG on "unstructured" input, if you would<br>
like to share with us your application cases, I am all ears as well.<br>
<br>
All the best, Marco<br>
<br>
Am Sa., 16. Apr. 2022 um 07:58 Uhr schrieb Yunzhuang Shen<br>
<s3640365@student.rmit.edu.au>:<br>
><br>
> Hi SCIP folks,<br>
><br>
> I am using GCG 3.5 (with SCIP 8.0.0) to solve MIPLIB instances with the decomposition tag.<br>
><br>
> I find that for some of these instances such as "academictimetablesmall", GCG terminates with the segmentation fault. So I ran the program in debug mode and the attached file is the output. I also tried GCG 3.0.5 (with SCIP 7.0.3) to solve the same instance
"academictimetablesmall" and GCG seems to be fine.<br>
><br>
> Regards,<br>
> Yunzhuang<br>
><br>
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-- <br>
Prof. Dr. Marco Lübbecke<br>
RWTH Aachen University<br>
Chair of Operations Research<br>
Kackertstrasse 7<br>
D-52072 Aachen<br>
Germany<br>
<br>
fon / fax: +49 241 80-93362 / 92369<br>
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