@Test
public void testSubtract() {

  final Summation sigma = newSummation(3, 10000, 20);
  final int size = 10;
  final List<Summation> parts = Arrays.asList(sigma.partition(size));
  Collections.sort(parts);
  runTestSubtract(sigma, new ArrayList<Summation>());
  runTestSubtract(sigma, parts);
  for(int n = 1; n < size; n++) {
    for(int j = 0; j < 10; j++) {
      final List<Summation> diff = new ArrayList<Summation>(parts);
      for(int i = 0; i < n; i++)
        diff.remove(RANDOM.nextInt(diff.size()));
/        Collections.sort(diff);
      runTestSubtract(sigma, diff);
    }
  }
}