Theorem 2: JACCARD-TRIANGULATION is NP-hard.
We next proceed to discuss our proposed algorithm for the
JACCARD-TRIANGULATION problem. The idea is to introduce
a variable xi for every element i ∈ U. The variable xi
indicates
if element i belongs in the solution set X. In particular, xi = 1
if i ∈ X and xi = 0 otherwise. We then assume that the size
of set X is t, that is,