Summing over sets already indexed - error F

Controlled set

Errors occur when one treats the same SET more than once [(i.e., process is summed over twice in the expression

sum((resource,process),SUM(PROCESS,RESOURUSE(RESOURCE,PROCESS)));]

or where an equation is defined over a set and one tries to sum over it.  For example in the following case RESOURCE defines the equation and is summed over

resource2(resource,process)=sum(process,RESOURUSE(RESOURCE,PROCESS));

Such errors are marked with message $125. The example shorterr08.gms illustrates such errors under the use of the errmsg=1 option which repositions the error message explanatory text.

  26 AVAILABLE(RESOURCE).. SUM((PROCESS,RESOURCE),RESOURUSE(RESOURCE,PROCESS)

****                                           $125     

**** 125  Set is under control already

  27                     *PRODUCTION(PROCESS))  =L= RESORAVAIL(RESOURCE);

  28  scalar x;

  29  x=sum((resource,process),SUM(PROCESS,RESOURUSE(RESOURCE,PROCESS)));

****                                      $125

**** 125  Set is under control already

  30  parameter resource2(resource,process);

  31  resource2(resource,process)=sum(process,RESOURUSE(RESOURCE,PROCESS));

****                                      $125

**** 125  Set is under control already