SETS:
 
nodes/1..7/:w,z,y;
 
arcs(nodes,nodes)|&1#LT#&2:c,x;
 
 
 
ENDSETS
 
DATA:
 
w =  0  5 7 4 8 6 5;
 
cap= 21;
 
c=    15  18  35   20  25  50
          20  40   35  37  35
              20   33  43  40
                   25  40  60
                       15  70
                           72
;
 
 
y=0   27 10 37 36 24 71
; 
 
 
ENDDATA
 
L= @SUM(arcs(i,j): c(i,j)*x(i,j));
prize=@SUM(nodes(i): z(i)* y(i));
 
min = L-prize;
 
@FOR(nodes(i):
           @SUM(arcs(i,j): x(i,j) ) + @SUM(arcs(j,i): x(j,i) ) = 2* z(i)
    )
;
 
@FOR(arcs(i,j): x(i,j) < z(i) ; x(i,j) < z(j) );
 
@SUM(nodes(i) : w(i)*z(i) ) < cap ;
z(1)=1;
 
@FOR(arcs:@BND(0,x,1);@GIN(x)); 
@FOR(nodes: @BND(0,z,1);@GIN(z));