Abstract   Given a set  S  of  n  integers, the problem is to decide whether there exist two disjoint nonempty subsets  S  1 , S  2 ⊆ S  whose elements sum up to the same value. We show this problem to be NP-complete and we present an approximation algorithm with worst-case ratio 1.324 for the optimization version of this problem.
['Gerhard J. Woeginger', 'Zhongliang Yu']
On the equal-subset-sum problem