MODEL:
! We have a network of 7 cities. We want to find
the length of the shortest route from city 1 to city 7;
sets:
! Here is our primitive set of seven cities;
cities/A, B1, B2, C1, C2, C3, D/;
! The Derived set "roads" lists the roads that
exist between the cities;
roads(cities, cities)/
A,B1 A,B2 B1,C1 B1,C2 B1,C3 B2,C1 B2,C2 B2,C3
C1,D C2,D C3,D/: w, x;
endsets
data:
! Here are the distances that correspond
to above links;
w = 2 4 3 3 1 2 3 1 1 3 4;
enddata
n=@size(cities); ! The number of cities;
min=@sum(roads: w*x);
@for(cities(i) | i #ne# 1 #and# i #ne# n:
@sum(roads(i,j): x(i,j)) = @sum(roads(j,i): x(j,i)));
@sum(roads(i,j)|i #eq# 1 : x(i,j))=1;
END