<div dir="ltr"><div><div><div>Hi Suyun,<br><br></div>if the initial point is specified in the .nl file, then Couenne does read and check that solution for MINLP feasibility, and if all is good it uses its objective function as a cutoff.<br><br></div>Regards,<br></div>Pietro<br></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Apr 2, 2018 at 6:55 PM, Suyun Liu <span dir="ltr"><<a href="mailto:sul217@lehigh.edu" target="_blank">sul217@lehigh.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hi <span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">Pietro,</span><div><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><br></span></div><div><span style="font-size:12.8px">Appreciate for your response very much. As far as I know, when constructing a model through Pyomo and writing it to the .nl file,  the so-called<b> <span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">primal initial guess</span></b><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"> is then indicated in that file. </span>Does that mean Couenne will ignore <span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">the primal initial guess (a possibly feasible solution) in the .nl file? </span></span></div><div><span style="font-size:12.8px"><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><br></span></span></div><div><span style="font-size:12.8px"><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">Best Regards,</span></span></div><div><span style="font-size:12.8px"><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">Suyun</span></span></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Apr 2, 2018 at 1:18 PM, Pietro Belotti <span dir="ltr"><<a href="mailto:petr.7b6@gmail.com" target="_blank">petr.7b6@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><div><div>Hi Suyun,<br><br></div>Couenne doesn't have a way to add a solution for use in pruning, so I think only art_cutoff (see my other response) can be used.<br><br></div>Regards,<br></div>Pietro<br></div><div class="gmail_extra"><br><div class="gmail_quote"><div><div class="m_407273830443625316h5">On Sat, Mar 31, 2018 at 4:48 PM, Suyun Liu <span dir="ltr"><<a href="mailto:sul217@lehigh.edu" target="_blank">sul217@lehigh.edu</a>></span> wrote:<br></div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="m_407273830443625316h5"><div dir="ltr">Hi all,<div><br></div><div>I have a question about initialization. Could Couenne accept a known feasible solution (hence upper bound) to accelerate pruning nodes on the tree? If so, which options could be used to impose the feasible objective value to the solver?  It seems like artificial cutoff doesn't work as we want. I am using Pyomo as the interface and the warmstart is not supported actually.</div><div><br></div><div>Thanks!</div><div><br></div><div>Best Regards,</div><div>Suyun</div></div>
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