Benchmarks Library ballred.gif (861 bytes) Multicommodity flow problem
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 GAMS-model         

ballred.gif (861 bytes)  Multicommodity flow problem 

ballred.gif (861 bytes)  Benchmarks

ballred.gif (861 bytes)  GAMS-model
$setglobal L 3

* These options limit the amount of information printed to the .lst file
option limrow = 0;
option limcol = 0;
option solprint = off;
option Profile=0;


*======================================================
* Change this to load an actual data file:

$include "instance.gms"
*======================================================


alias (i,j,u,k,v);

set level /1*%L%/;
scalar LL /%L%/;
alias (level,level1,level2);

scalar tr_sum the total demand;
tr_sum=0;
loop((k,v)$(not sameas(k,v) and tr(k,v)>0),
  tr_sum=tr_sum+tr(k,v);
);

tr_sum = tr_sum*1024*1024;
display tr_sum;

set feasX(i,j,k,v) feasible combinations of indices;
feasX(i,j,k,v)$(d(i,j)>0 and tr(k,v)>0 and not sameas(k,v) and not sameas(i,j)
   and not sameas(j,k) and not sameas(i,v)) = yes;

scalar total_traffic;

total_traffic=sum((k,v)$(not sameas(k,v)), tr(k,v));

display total_traffic;
scalar n_arcs;
n_arcs=0;
loop((i,j)$(d(i,j)>0), n_arcs=n_arcs+1);

display n_arcs;

file path_stats /_path_stats.txt/;

scalar solving_time;
file stats /leveled_lp_stats.txt/;


positive variables x(i,j, k,v,level);
variable f;

equations
  cObj
  cBandwidth
  cTrafficDemand
  cTrafficBalance
  cTrafficBalance1
;

cObj..
  f =e= sum((k,v)$(not sameas(k,v) and tr(k,v)>0),
          sum((feasX(k,j,k,v),level)$(ord(level)=1), x(k,j,k,v,level))
        );

cTrafficDemand(k,v)$(not sameas(k,v) and tr(k,v)>0)..
  sum((feasX(k,j,k,v),level)$(ord(level)=1), x(k,j,k,v,level)) =l= tr(k,v);

cBandwidth(i,j)$(not sameas(i,j) and d(i,j)>0)..
  sum((feasX(i,j,k,v),level)$(ord(level)0 and ord(level2)0 and ord(level)=LL)..
    sum(i$(feasX(i,u,k,v) or sameas(i,u)), x(i,u,k,v,level)) =e= 0;

model routing /
  cObj
  cBandwidth
  cTrafficDemand
  cTrafficBalance
  cTrafficBalance1
/;

option iterlim=1.e9;
option iterlim=1.e9;
option limrow = 0;
option limcol = 0;
routing.reslim = 10000;
solve routing using LP maximizing f;