[Help-glpk] symbolic parameter in set

[Park, Joseph]

In version 4.8 there is a nice example: maxflow.mod

 

regarding this example, how does one declare and assign a

symbolic (string) parameter within the Arcs set?

 

i.e., I would like to assign a 'name' parameter to Arcs:

 

param n, integer, >= 2;
/* number of nodes */

 

set Nodes, default {1..n};
/* set of nodes */

 

set Arcs, within Nodes cross Nodes;
/* set of arcs */

 

param capacity {(i,j) in Arcs}, > 0;
/* capacity[i,j] is capacity of arc (i,j) */

 

param name, symbolic, {(i,j) in Arcs};

.....

 

data;

 

param : Arcs : name  capacity :=
       1 2   arc1  14
       1 4   arc2  23

       ....;

 

with the line 23 as: param name, symbolic, {(i,j) in Arcs};

I get:

Reading model section from maxflow.mod...
maxflow.mod:23: syntax error in parameter statement
Context: ...city { ( i , j ) in Arcs } , > 0 ; param name , symbolic , {
Model processing error

 

 

Thank you...