[SCIP] SCIP speed-up for .LP files

[Tobias Achterberg]

Hi Marcus,

it should also be possible in Gurobi to generate all feasible solutions. You need to set 
PoolSearchMode=2 and PoolSolutions=2000000000. If you only want to generate all optimal 
solutions, then you should use PoolGap=0 in addition to the two other parameters.

But note that SCIP has some clever additional strategies for enumerting and storing 
multiple solutions (thanks to Stefan Heinz) that Gurobi does not have. So, it might be 
that for this purpose, SCIP has an advantage. You need to try.


Best regards,

Tobias



Am 2018-06-14 um 23:21 schrieb Marcus Garvie:
> Hi everyone,
> 
> this is my first post, so please understand that my knowledge of SCIP is low!
> 
> I have been solving some large binary linear programming problems with no objective 
> function. I solve .LP files using a terminal to issue the commands on my Mac. The .LP 
> files are automatically generated, with e.g. the attached format.
> 
> The only commands I issue are
> 
> SCIP> read test.lp
> SCIP> optimize test.lp
> 
> The problem is that for very large problems (e.g. 28456 variables) the solver seems to be 
> running forever (> 2 days)! I tried the same problem in Gurobi and it gave me the correct 
> solution in 15 minutes. (I’m wanting to use SCIP because it has some easy options for 
> giving me all feasible solutions, while Gurobi does not).
> 
> I also tried the problem in CPLEX, but it has some limitations on the length of the 
> variable names (Error  1464) so I’m a little stuck if I want multiple solutions for large 
> problems.
> 
> Any advice would be appreciated.
> 
> Marcus.
> 
> PS I only know how to problems in the  .LP format!
> 
> 
> 
> ________________________________
> Marcus R Garvie
> Associate Professor
> Rm 552 MacNaughton Bldg
> Dept. of Math & Stats
> University of Guelph
> Guelph, ON Canada N1G 2W1
> Tel. 519-824-4120 ext 53409
> Email. _mgarvie at uoguelph.ca_ <mailto:mgarvie at uoguelph.ca>
> 
> 
> 
> 
> 
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