<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /></head><body style='font-size: 10pt; font-family: Verdana,Geneva,sans-serif'>
<p>Dear SCIP community,</p>
<p>We are working in a MIP program which has three families of constraints:</p>
<ul>
<li>441 model constraints that are always present in the problem.</li>
<li>19 model constraints (weak) that model completely the problem.</li>
<li>7600 model constraints (strong) that model the problem by means of a tighter formulation.</li>
</ul>
<p>Moreover the weak constraints are the aggregation of the strong constraints and either of the two could model the problem without the other.</p>
<p>We have written the separator plugin, but we would like to check how SCIP handles user cuts or lazy constraints automatically. Defining or not the <em>weak constraints</em>, we have tested a couple of options on the parameters of the function SCIPcreateConsLinear() when creating the <em>strong constraints</em>.</p>
<ol>
<li>Strong constraints initially defined.</li>
<li><span>(lazy constraints) Strong constraints not initially defined but set to be enforced.</span></li>
<li>Weak and strong constraints initially defined.<span></span></li>
<li><span>(user cuts) Weak constraints initially defined plus strong constraints not initially defined.</span><span></span></li>
</ol>
<p><span>Attached you have the results. Our questions are the following:</span></p>
<ul>
<li><span>Since the problem can be solved at the root node using strong constraints, we guess that option (2) branches because SCIP decides automatically not checking all the fractional solutions but the integer ones. Are we right?</span></li>
<li><span>Since the problem can be solved at the root node using strong constraints, we guess that option (4) branches because SCIP decides automatically not checking all the fractional solutions. Are we right?</span></li>
<li>To avoid other cuts we use the below function. Is it enough?</li>
</ul>
<p> SCIP_CALL( SCIPsetSeparating(scip, SCIP_PARAMSETTING_OFF, TRUE) );<span></span></p>
<ul>
<li>What does confs mean in the interactive shell?</li>
<li>How could we obtain the number of lazy constraints in (2)? Would SCIPgetNCutsApplied(scip) be right?</li>
<li>How could we obtain the number of user cuts in (4)? Would SCIPgetNEnabledConss(scip) - SCIPgetNCheckConss(scip) be right?</li>
</ul>
<p>Best,</p>
<p>Diego Ponce</p>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<meta http-equiv="Content-Type" content="text/html charset=UTF-8" />
<style>
@import url('https://fonts.googleapis.com/css?family=Roboto:400,700');
</style>
<body>
<table style="font-family:Roboto; border-top: solid 1px #ddd; padding-top: 15px;">
<tr>
<td width="360" valign="top">
<img src="https://sic.us.es/sites/default/files/servicios/correo/Archivos/us_logo.jpg"/>
</td>
</tr>
</table>
<table style="font-family:Roboto; width: 360px; background-color: #f3f3f3; margin-top: 15px; padding: 3px 3px 5px 3px; border-spacing: 5px; text-align: center;">
<tr>
<td width="215" valign="top">
<a href="http://www.us.es/" target="_blank" style="margin: 0 auto; text-decoration: none; font-size: 16px;">
<span style="color: #000; text-decoration: underline;">www.us.es</span>
</a>
</td>
</tr>
</table>
<table style="font-family:Roboto; width: 360px; font-size: 9px; padding-top: 20px; border-spacing: 5px;">
<tr>
<td width="215" valign="top">
<span style="color: #339966;">Por favor considere el medio ambiente antes de imprimir este correo electrónico. </span>
<br>-<br>
<span style="color: #999999;">Este correo electrónico y, en su caso, cualquier fichero anexo al mismo, contiene información de carácter confidencial exclusivamente dirigida a su destinatario o destinatarios. Si no es Vd. el destinatario del mensaje, le ruego lo destruya sin hacer copia digital o física, comunicando al emisor por esta misma vía la recepción del presente mensaje. Gracias</span>
</td>
</tr>
</table>
</body>
</html>
</body></html>