1285755842

Source: LPFormat.rar
File: upload/29.09.2010_1285755842_Dmitry_Krushinsky/LPFormat.rar
Name: Dmitry_Krushinsky
Company: University of Groningen
eMail: d.krushinsky@rug.nl
Street: Nettelbosje 2
City: Groningen
Country: NETHERLANDS (NL)
Message: The attached instances represent a MILP formulation 
of the p-Median problem (PMP) defined on square cost matrices. 
The entries of the cost matrices were selected in such a way that
all known problem size reduction techniques (except of the 
so-called p-truncation) for PMP do not work. As a result, 
moderate size PMP instances with 100, 200 nodes lead to huge 
MILP formulations that, as we expect, will be hard to solve.
We tried solving instances from LP_rmatr100,1,p=5.txt and
LP_rmatr100,1,p=10.txt with Xpress-MP on a personal computer
and the running times were 3443 and 1141 sec., correspondingly.

The file names are of the following format LP_rmatrX,Y,p=Z.txt
where
X - size of the initial cost matrix for PMP
Y - range of coefficients in the objective
Z - number of p-medians
The archive also contains initial cost matrices (rmatr100,1.txt
and rmatr200,1.txt). 

delivered on: 29.09.2010
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