gistfile1.txt

% given an array of k subsets of numbers 1..n
% select a subset of 1..n such that at most one 
% member of every subset is in it and the sum is maximized

int: n;  % numbers from 1 to n 
int: k;  % number of subsets
set of int: OBJ = 1..n;
set of int: SET = 1..k;
int: u;

% copied from dzn file; setselect sample data
n = 10;
k = 7;
s = [{1,5,6}, {2,6,7,10}, {3,6,8}, {1,2,3}, {2,9,10}, {5,8,10}, {7,8,10}];
u = 3;

array[SET] of set of OBJ: s;

% HERE is the error: should be set of OBJ
var set of int: x;

% must contain at must one shared element
constraint forall(j in 1..k) ( card( x intersect s[j] ) <= 1 );
constraint card(x) = u;

solve maximize sum(i in x) (i);