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by UserCplex
28 Nov 2019, 01:19
Forum: Helpdesk
Topic: Error in using lp2poly
Replies: 21
Views: 4063

Re: Error in using lp2poly

(post edited)

Yes, that approach did work for me. I was able to get the 125 points myself and have been able to obtain the facets of the projection polytope using polymake bypassing the time-consuming FM elimination projection algorithm.

Thanks for your help.
by UserCplex
27 Nov 2019, 18:38
Forum: Helpdesk
Topic: Error in using lp2poly
Replies: 21
Views: 4063

Re: Error in using lp2poly

Hi Thomas, I am mostly (only) interested in figuring out the facets of the feasible region of the integer/binary variables in my .lp file. So, in this example, in the .lp file, I would like to know the equations defining the facets of the polyhedron (defined for integer feasible solutions) projected...
by UserCplex
27 Nov 2019, 15:08
Forum: Helpdesk
Topic: Error in using lp2poly
Replies: 21
Views: 4063

Re: Error in using lp2poly

Thank you for the additional information. I am not very knowledgeable about how FM elimination is used within the projection algorithm. However, in this case atleast where I am projecting into the subspace of two binary integer variables, it seems to me that full fledged FM elimination (assuming tha...
by UserCplex
27 Nov 2019, 12:46
Forum: Helpdesk
Topic: Error in using lp2poly
Replies: 21
Views: 4063

Re: Error in using lp2poly

Inside polymake, I typed sequentially. $f=lp2poly('problemIP_polymake.lp');#lp file from cplex. Should be OK $p = new Polytope<Rational>($f); $q = projection($p, [1,2]);#projects p into space of 1st and 2nd variable, which are binary integer _e0_1#0 and _e0_2#1 The last of the lines, where the proje...
by UserCplex
27 Nov 2019, 11:44
Forum: Helpdesk
Topic: Error in using lp2poly
Replies: 21
Views: 4063

Re: Error in using lp2poly

Thank you gawrilow. I confirm being able to get the optimal MIP solution using the workaround you provided. For this very same problem (.lp file as attached in my immediately previous message), I was trying to project the solution space into the space of pure binary variables only (_e*) variables in...
by UserCplex
27 Nov 2019, 03:17
Forum: Helpdesk
Topic: Error in using lp2poly
Replies: 21
Views: 4063

Re: Error in using lp2poly

Thomas, I did what you suggested -- changed the two problem constraints into integer RHS (that modified .lp file is attached with this message). Then, I ran the following set of commands in a script: use application "polytope"; use vars qw($f $p); $f=lp2poly('problemIP_polymake.lp');#lp file from cp...
by UserCplex
26 Nov 2019, 20:01
Forum: Helpdesk
Topic: Error in using lp2poly
Replies: 21
Views: 4063

Re: Error in using lp2poly

I figured out that lattice points in polymake refer exclusively to all integer points of all variables. It is indeed the case that my original .lp file does not have a feasible integer solution where all variables have to be either 0 or 1. However, now, I am running into a different error (I upgrade...
by UserCplex
26 Nov 2019, 18:53
Forum: Helpdesk
Topic: Error in using lp2poly
Replies: 21
Views: 4063

Re: Error in using lp2poly

Thank you. I will install the latest version and try. However, I am a bit puzzled as to why your correct version of polymake says that there is no lattice point. I know, for instance, that the following variable values is indeed optimal for the given MIP. (variable values are displayed towards the b...
by UserCplex
26 Nov 2019, 14:31
Forum: Helpdesk
Topic: Error in using lp2poly
Replies: 21
Views: 4063

Error in using lp2poly

Hello, I have a cplex generated LP file, problemIP_polymake.lp that is attached. This is a mixed integer program with both 0/1 binary variables, as well as continuous variables which range in [0,1]. The problem is bounded. I have a file lp2poly.sh the contents of which are: However, on doing so, I g...
by UserCplex
10 Mar 2019, 12:55
Forum: General Discussion
Topic: Enumerating all integer feasible points, CPLEX vs Polymake
Replies: 19
Views: 6072

Re: Enumerating all integer feasible points, CPLEX vs Polymake

Hi Opfer/Gawrilow, I created a lp2polyfloat.sh file to automate the task of reading in an LP file and computing the facets "quickly" by using Floats instead of Rationals as suggested earlier in this thread. The script file content is: However, on running this script thus: terminalprompt> polymake --...

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