[SCIP] SCIP GAMS interface

[Akang Wang]

Hi SCIP developers,

I'm Akang. I'm calling SCIP 5.0 through GAMS 25.0.2. (Attached is the gams
file, CPLEX 12.8.0 is the LP solver).

My question is, SCIP generates the primal and dual bounds
(Initial_status.PNG). We know that in the minimization problem, the primal
bound is the upper bound (from a feasible solution). Why does SCIP check
feasibility here (Initial_status.PNG)?  After time limit is hit, why does
SCIP further call IPOPT to find a feasible solution (and generate an upper
bound in this case)?  Then the primal bound is updated by a worse value
from the IPOPT solution (status_update.PNG, Also, what does the gap mean
here because it is not (UB-LB)/UB?).

Could anybody elaborate on this?



-- 
Akang Wang
Ph.D. Candidate
Department of Chemical Engineering
Carnegie Mellon University
5000 Forbes Avenue, Pittsburgh, PA 15213
akangw at andrew.cmu.edu
akangw.github.io
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listserv.zib.de/pipermail/scip/attachments/20180425/f1af03b7/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: GAMS.gms
Type: application/octet-stream
Size: 2049 bytes
Desc: not available
URL: <http://listserv.zib.de/pipermail/scip/attachments/20180425/f1af03b7/attachment.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Initial_status.PNG
Type: image/png
Size: 26273 bytes
Desc: not available
URL: <http://listserv.zib.de/pipermail/scip/attachments/20180425/f1af03b7/attachment.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: status_update.PNG
Type: image/png
Size: 8300 bytes
Desc: not available
URL: <http://listserv.zib.de/pipermail/scip/attachments/20180425/f1af03b7/attachment-0001.png>