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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
(default)
--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
(default)
--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
>>