Group

public class Group {

  // Group Management

  public int size() {...}

  public int rank() {...}

  public int [] translateRanks(Group group1, int [] ranks1) {...}

  public static int compare(Group group1, Group group2) {...}

  public static Group union(Group group1, Group group2) {...}

  public static Group intersection(Group group1, Group group2) {...}

  public static Group difference(Group group1, Group group2) {...}

  public Group incl(int [] ranks) {...}

  public Group excl(int [] ranks) {...}

  public Group rangeIncl(int [] [] ranges) {...}

  public Group rangeExcl(int [] [] ranges) {...}

  public void finalize() {...}

  ...
}