Hi everyone, thanks for your help,

I am just been introduced to AMPL programming and I don’t know what is the problem of a constraint that gives a which is in the iis of the problem I am trying to solve.

The constraint is the following:

subject to EACH_RESOURCE {k in K}:

1 = sum{j in J} x[k,j];

It is used to restric each resource to be placed just in one area

Definitions are as follows:

set K;

#resources availables

set J;

#centers for resource placement

var x {k in K, j in J} binary;

#resource k is placed at j

The result of cplex solver is the follwing:

option iis_table ’

0 non not in the iis

1 low at lower bound

2 fix fixed

3 upp at upper bound

4 mem member

5 pmem possible member

6 plow possibly at lower bound

7 pupp possibly at upper bound

8 bug

';

ampl: display EACH_RESOURCE.iis;

EACH_RESOURCE.iis [*] :=

K1 non

K3 mem

K4 non

;

And on the .dat file:

set K:= K1 K2 K3 K4;

set J:= J1 J2 J3 J4;

I know that my knowledge is not the best, since I am a student at a phinal project, but I am really stuck with the modeling and I would appreciate some help.