<div dir="ltr">Hi all.<div><br></div><div>Thanks for the reply Benny.</div><div><br></div><div>I created the following input file to the framework.</div><div><div>STATISTICS</div><div> Problem name : test.cip</div><div> Variables : 5 (0 binary, 5 integer, 0 implicit integer, 0 continuous)</div><div> Constraints : 0 initial, 5 maximal</div><div>OBJECTIVE</div><div> Sense : minimize</div><div>VARIABLES</div><div> [integer] <c#0b#0>: obj=0, original bounds=[0,1]</div><div> [integer] <c#1b#0>: obj=0, original bounds=[0,1]</div><div> [integer] <c#0b#1>: obj=0, original bounds=[0,1]</div><div> [integer] <c#1b#1>: obj=0, original bounds=[0,1]</div><div> [integer] <y#0>: obj=0, global bounds=[0,4], local bounds=[0,4]</div><div>CONSTRAINTS</div><div> [linear] <pack_1>: <c#0b#0>[I] +<c#0b#1>[I] == 1;</div><div> [linear] <pack_2>: <c#1b#0>[I] +<c#1b#1>[I] == 1;</div><div> [linear] <cap_0>: <c#0b#0>[I] +<c#1b#0>[I] <= 1;</div><div> [linear] <cap_1>: <c#0b#1>[I] +<c#1b#1>[I] <= 1;</div><div> [linear] <obj_0>: -<c#0b#1>[I]*<c#1b#1>[I]*1 -<c#0b#0>[I]*<c#1b#0>[I]*1 +4 -<y#0> == 0;</div><div>END</div></div><div><br></div><div>The results should assign y#0 to 4. However, I get the following output (snippet of output to reduce length):</div><div><div><br></div><div>presolving (1 rounds: 1 fast, 1 medium, 1 exhaustive):<br></div><div> 5 deleted vars, 5 deleted constraints, 0 added constraints, 1 tightened bounds, 0 added holes, 0 changed sides, 0 changed coefficients</div><div> 0 implications, 0 cliques</div><div>presolved problem has 0 variables (0 bin, 0 int, 0 impl, 0 cont) and 0 constraints</div><div>transformed objective value is always integral (scale: 1)</div><div>Presolving Time: 0.00</div><div><br></div><div>objective value: 0</div><div>c#0b#0 1 <span style="white-space:pre"> </span>(obj:0)</div><div>c#1b#1 1 <span style="white-space:pre"> </span>(obj:0)</div></div><div><br></div><div>The assignment of c#0b#0 and c#1b#1 are valid solutions. I am confused on the reason that the objective value is 0. I am assume that the objective value is y#0, since it is the only variable not stated. The value of y#0 should be 4.</div><div><br></div><div>Some guidance would be appreciated. Note that I searched the SCIP mailing list archive but I did not find any references for the input format and description of the output.</div><div><br></div><div>Any help would be appreciated. Thank you.<br><br class="gmail-Apple-interchange-newline"></div><div><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Feb 13, 2018 at 11:38 PM, Benjamin Müller <span dir="ltr"><<a href="mailto:benjamin.mueller@zib.de" target="_blank">benjamin.mueller@zib.de</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi Vincent,<br>
<br>
I would recommend using JSCIPOpt, which is our SCIP-Java interface that can be found here:<br>
<br>
<a href="https://github.com/SCIP-Interfaces/JSCIPOpt" rel="noreferrer" target="_blank">https://github.com/SCIP-Interf<wbr>aces/JSCIPOpt</a><br>
<br>
All relevant steps for building the interface are listed in the INSTALL.md, but basically, you will need to download the latest SCIP Optimization Suite and compile it with Ipopt. You might want to have a look at the JSCIPOpt/examples/Quadratic, which shows how to model a problem with simple quadratic constraints.<br>
<br>
Please note that SCIP can't handle a nonlinear objective function. For this reason, you need to add an auxiliary variable z and then model your problem as<br>
<br>
min z<br>
z >= sum_{ij} X_{ij} Y_{ij}<br>
...<br>
<br>
Best,<br>
Benny<span class=""><br>
<br>
On 02/13/2018 07:05 PM, Vincent Mirian wrote:<br>
</span><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class="">
HI all.<br>
<br>
I am new to the SCIP community.<br>
<br>
I am looking for a non-linear solver to solve:<br>
- an objective function similar to 0 <= sum over i and j of X_ij * Y_ij * Constant < max<br></span>
- with constraints similar tosum(X_ij) = 1 and sum(Y_ij) = 1 (forcing the values of X_ij and Y_ij to zero or one). A solution would be sufficient (it can be local or global optimal).<span class=""><br>
<br>
I would need to interface the solver with Java. I found Google Optimization Tools (OR-Tools) to interface SCIP with java. Note that this work is for academic research.<br>
<br>
- Would SCIP or Ipopt be suitable for my task? Would anyone have experience integrating SCIP or Ipopt into Java?<br>
- I'm using a machine with ubuntu 64-bit. Are there any issues with installing these tools in this machine environment?<br>
- What is the manner to describe the constraints and objective function using these tools?<br>
<br>
Thank you.<br>
-- <br>
Vincent Mirian<br>
<br>
<br></span>
______________________________<wbr>_________________<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/mailma<wbr>n/listinfo/scip</a><br>
<br><span class="HOEnZb"><font color="#888888">
</font></span></blockquote><span class="HOEnZb"><font color="#888888">
<br>
-- <br>
______________________________<br>
Benjamin Müller<br>
Zuse Institute Berlin<br>
Takustr. 7, 14195 Berlin<br>
<a href="mailto:benjamin.mueller@zib.de" target="_blank">benjamin.mueller@zib.de</a><br>
<a href="tel:%2B49%2030%20841%2085-195" value="+493084185195" target="_blank">+49 30 841 85-195</a><br>
</font></span></blockquote></div><br><br clear="all"><div><br></div>-- <br><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div>Vincent Mirian</div></div></div></div>
</div>