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Re: [Help-glpk] Asking help on an issue of solving via glpk

From: Noli Sicad
Subject: Re: [Help-glpk] Asking help on an issue of solving via glpk
Date: Tue, 9 Feb 2016 09:48:04 +1100

Hi John,

glpsol --help

The above  will give you all the help / info / options.

Here's the one, the results that I copy and paste for the MIP solver
options (below)

Options specific to MIP solver:
   --nomip           consider all integer variables as continuous
                     (allows solving MIP as pure LP)
   --first           branch on first integer variable
   --last            branch on last integer variable
   --mostf           branch on most fractional variable
   --drtom           branch using heuristic by Driebeck and Tomlin
   --pcost           branch using hybrid pseudocost heuristic (may be
                     useful for hard instances)
   --dfs             backtrack using depth first search
   --bfs             backtrack using breadth first search
   --bestp           backtrack using the best projection heuristic
   --bestb           backtrack using node with best local bound
   --intopt          use MIP presolver (default)
   --nointopt        do not use MIP presolver
   --binarize        replace general integer variables by binary ones
                     (assumes --intopt)
   --fpump           apply feasibility pump heuristic
   --proxy [nnn]     apply proximity search heuristic (nnn is time limit
                     in seconds; default is 60)
   --gomory          generate Gomory's mixed integer cuts
   --mir             generate MIR (mixed integer rounding) cuts
   --cover           generate mixed cover cuts
   --clique          generate clique cuts
   --cuts            generate all cuts above
   --mipgap tol      set relative mip gap tolerance to tol
   --minisat         translate integer feasibility problem to CNF-SAT
                     and solve it with MiniSat solver
   --objbnd bound    add inequality obj <= bound (minimization) or
                     obj >= bound (maximization) to integer feasibility
                     problem (assumes --minisat)

Regards, Noli

On 2/9/16, john tass <address@hidden> wrote:
> Thanks a lot to all of them who answered my question.
> Should I suppose that the answer to my question is negative, i.e. it is not
> possible to force GLPK to start searching from a particular point?
> For your information, my project concerns the school timetabling problem.
> As I mentioned in my previous mail, I got a solution provided by Particle
> Swarm Optimization, but I do not know if this solution is optimal or not.
> Any way, I found your answers very helpful. What I wrote in command prompt
> was :
> glpsol --cuts --pcost --math my_model.mod --data my_data.dat --proxy 200
> --mir --mipgap 0.2
> The results were good and produced fast.
> Nevertheless, I mast say that I have no idea about what --cuts, --pcost,
> --proxy, --mir and --mipgap 0.2 mean or stand for.
> Could any one inform me in a few words about the meaning of all these? Or
> better, is there any text explaining all these?
> Please note that the asked information is very crucial to me, as I shall be
> in a position to explain the way or the method I followed in order to
> discover these better solutions, compared with those found by Particle
> Swarm optimization.
> Thanks for one more time
> 2016-02-08 23:21 GMT+02:00 Noli Sicad <address@hidden>:
>> Hi  Johannes,
>> Try to use the proximity option and mipgap option as well, as
>> mentioned by Heinrich.
>> For example,
>> glpsol --math yourMIP_mathprog_model.mod --proxy 200 --mir --mipgap 0.2
>> Note: 200 in the example above is in seconds.
>> Regards, Noli

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