<div dir="ltr">It also took me a while to figure out how to do a restart and had several communications with a scip person to sort it out.<div><br></div><div>This is what works for me.</div><div>Just before you make your first change after an optimize, do those three calls:</div><div><br></div><div> ret = SCIPfreeTransform(scip);<br> ret = SCIPenableReoptimization(scip, 0);<br> ret = SCIPfreeReoptSolve(scip);<br></div><div><br></div><div>After these you can change bounds, add/remove variables, add/remove constraints and then do again a SCIPsolve</div><div><br></div><div>See also my sciptest program in sciptest2.cpp at <a href="https://github.com/peno64/sciptest">https://github.com/peno64/sciptest</a></div><div><br></div><div>Peter</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, 11 Sept 2023 at 11:08, Lastra Diaz Jose <<a href="mailto:j.lastra@lectra.com">j.lastra@lectra.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div class="msg-5402356725614135307">
<div lang="EN-GB">
<div class="m_2382638731206193723WordSection1">
<p class="MsoNormal"><span lang="ES" style="font-size:10pt;font-family:Arial,sans-serif">Dear colleagues,<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="ES" style="font-size:10pt;font-family:Arial,sans-serif"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:10pt;font-family:Arial,sans-serif">I want to implement an ad-hoc Benders-like decomposition of a MIP model, and I would like to know if its is possible to change the LB and UB of a decision variable and reoptimize
an MIP model since its last state.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:10pt;font-family:Arial,sans-serif"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:10pt;font-family:Arial,sans-serif">My idea is to define a collection of binary variables as continuous variables with bounds [0,1] and then set their values after each iteration of the master problem before solving
the sub-problem again, I want to keep a single instance of the sub-problem throughout all iterations.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:10pt;font-family:Arial,sans-serif"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:10pt;font-family:Arial,sans-serif">Can we set the bounds of binary variables and reoptimize a MIP model?<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:10pt;font-family:Arial,sans-serif">How to do it?<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:10pt;font-family:Arial,sans-serif"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:10pt;font-family:Arial,sans-serif">Thank you in advance,<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:10pt;font-family:Arial,sans-serif">Juan<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:10pt;font-family:Arial,sans-serif"><u></u> <u></u></span></p>
<table border="0" cellspacing="0" cellpadding="0" width="0" style="width:16cm;border-collapse:collapse">
<tbody>
<tr style="height:78.5pt">
<td width="265" valign="top" style="width:7cm;padding:0cm 5.4pt;height:78.5pt">
<p class="MsoNormal" style="line-height:200%"><span style="font-size:12pt;line-height:200%"><img width="247" height="82" style="width: 2.575in; height: 0.8583in;" id="m_2382638731206193723Imagen_x0020_1" src="cid:image001.png@01D9E49E.1FA8C460" alt="cid:image001.png@01D4B3E6.540B6570"></span><span lang="FR" style="font-size:12pt;line-height:200%"><u></u><u></u></span></p>
</td>
<td width="340" valign="top" style="width:9cm;padding:0cm 5.4pt;height:78.5pt">
<p class="MsoNormal"><b><span lang="FR" style="font-size:10pt;font-family:Arial,sans-serif;color:black">Juan J. Lastra Díaz, PhD</span></b><span lang="FR" style="font-size:10pt;font-family:Arial,sans-serif;color:black"><u></u><u></u></span></p>
<p class="MsoNormal"><b><span lang="FR" style="font-size:10pt;font-family:Arial,sans-serif;color:rgb(192,0,0)">Advanced Research department</span></b><span lang="FR" style="font-size:10pt;font-family:Arial,sans-serif;color:black"><u></u><u></u></span></p>
<p class="MsoNormal"><span lang="FR" style="font-size:10pt;font-family:Arial,sans-serif;color:black"> <u></u><u></u></span></p>
<p class="MsoNormal"><b><span lang="FR" style="font-size:10pt;font-family:Arial,sans-serif;color:rgb(192,0,0)">t
</span></b><b><span lang="FR" style="font-size:10pt;font-family:Arial,sans-serif;color:black">:
</span></b><span lang="FR" style="font-size:10pt;font-family:Arial,sans-serif;color:black">+34 917 88 88 65<u></u><u></u></span></p>
<p class="MsoNormal"><b><span lang="FR" style="font-size:10pt;font-family:Arial,sans-serif;color:rgb(192,0,0)">e</span></b><b><span lang="FR" style="font-size:10pt;font-family:Arial,sans-serif;color:black">
: </span></b><span style="color:black"><a href="mailto:j.lastra@lectra.com" target="_blank"><span lang="ES" style="color:blue">j.lastra</span><span lang="FR" style="font-size:10pt;font-family:Arial,sans-serif;color:blue">@lectra.com</span></a></span><span lang="FR" style="font-size:10pt;font-family:Arial,sans-serif;color:black"><u></u><u></u></span></p>
</td>
</tr>
<tr style="height:2.95pt">
<td width="265" valign="top" style="width:7cm;padding:0cm 5.4pt;height:2.95pt">
<p class="MsoNormal" align="center" style="text-align:center"><span lang="ES"><a href="https://www.linkedin.com/company/8538/" target="_blank"><span lang="EN-GB" style="font-size:12pt;color:black;text-decoration:none"><img border="0" width="38" height="38" style="width: 0.4in; height: 0.4in;" id="m_2382638731206193723Imagen_x0020_2" src="cid:image002.png@01D9E49E.1FA8C460" alt="cid:image002.png@01D4B3E6.540B6570"></span></a><a href="https://www.facebook.com/LectraOfficial/" target="_blank"><span lang="EN-GB" style="font-size:12pt;color:black;text-decoration:none"><img border="0" width="38" height="38" style="width: 0.4in; height: 0.4in;" id="m_2382638731206193723Imagen_x0020_3" src="cid:image003.png@01D9E49E.1FA8C460" alt="cid:image003.png@01D4B3E6.540B6570"></span></a><a href="https://www.instagram.com/lectraofficial/" target="_blank"><span lang="EN-GB" style="font-size:12pt;color:black;text-decoration:none"><img border="0" width="38" height="38" style="width: 0.4in; height: 0.4in;" id="m_2382638731206193723Imagen_x0020_4" src="cid:image004.png@01D9E49E.1FA8C460" alt="cid:image004.png@01D4B3E6.540B6570"></span></a><a href="https://www.youtube.com/user/LectraTechChannel?hl=fr" target="_blank"><span lang="EN-GB" style="font-size:12pt;color:black;text-decoration:none"><img border="0" width="38" height="38" style="width: 0.4in; height: 0.4in;" id="m_2382638731206193723Imagen_x0020_5" src="cid:image005.png@01D9E49E.1FA8C460" alt="cid:image005.png@01D4B3E6.540B6570"></span></a><a href="https://blog.lectra.com/" target="_blank"><span lang="EN-GB" style="font-size:12pt;color:black;text-decoration:none"><img border="0" width="38" height="38" style="width: 0.4in; height: 0.4in;" id="m_2382638731206193723Imagen_x0020_6" src="cid:image006.png@01D9E49E.1FA8C460" alt="cid:image006.png@01D4B3E6.540B6570"></span></a></span><span lang="FR" style="font-size:12pt"><u></u><u></u></span></p>
</td>
<td width="340" valign="top" style="width:9cm;padding:0cm 5.4pt;height:2.95pt">
<p class="MsoNormal"><span lang="FR" style="font-size:8pt;font-family:Arial,sans-serif;color:black">C/ Vía de los Poblados, 1 - Edif. C, 1ª Plta.<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="FR" style="font-size:8pt;font-family:Arial,sans-serif;color:black">P.E. Alvento - 28033 Madrid - España<u></u><u></u></span></p>
<p class="MsoNormal"><span><a href="http://www.lectra.com/" target="_blank"><b><span lang="FR" style="font-size:10pt;font-family:Arial,sans-serif;color:black">lectra.com</span></b></a></span><span lang="FR" style="font-size:12pt"><u></u><u></u></span></p>
</td>
</tr>
</tbody>
</table>
<p class="MsoNormal"><span lang="FR"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:8pt;font-family:Arial,sans-serif">This e-mail and any attached files may contain confidential information which is intended exclusively for the recipient. If you are not the
specified recipient, you should delete this e-mail from your system immediately, and inform the sender without delay. Reading, distributing, copying, or any other unauthorized use of this e-mail and its attached files is strictly forbidden.
</span><span lang="FR" style="font-size:8pt;font-family:Arial,sans-serif">Thank you for your comprehension.<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="FR" style="font-size:8pt;font-family:Arial,sans-serif"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="ES" style="font-size:8pt;font-family:Arial,sans-serif">Este correo electrónico y cualquier archivo adjunto pueden contener información confidencial que está destinada exclusivamente al destinatario.
Si usted no es el destinatario especificado, debe eliminar este correo electrónico de su sistema inmediatamente e informar al remitente sin demora. Está terminantemente prohibido leer, distribuir, copiar o cualquier otro uso no autorizado de este correo electrónico
y sus archivos adjuntos. Gracias por su comprensión.</span><span lang="ES" style="font-size:8pt;font-family:Arial,sans-serif"><u></u><u></u></span></p>
<p class="MsoNormal"><span lang="ES"><u></u> <u></u></span></p>
</div>
</div>
_______________________________________________<br>
Scip mailing list<br>
<a href="mailto:Scip@zib.de" target="_blank">Scip@zib.de</a><br>
<a href="https://listserv.zib.de/mailman/listinfo/scip" rel="noreferrer" target="_blank">https://listserv.zib.de/mailman/listinfo/scip</a><br>
</div></blockquote></div>