for (int itemNumber = 0; itemNumber < group.size(); itemNumber++) {
        // check related items in same group
        for (int relatedItemNumber = 0; relatedItemNumber < group.size(); relatedItemNumber++) {
          if (itemNumber != relatedItemNumber) {
            assertRelated(groupNumber, itemNumber, relatedItemNumber);
          }
        }
        // check unrelated items in all other groups
        for (int unrelatedGroupNumber = 0;