public Collection<Artist> getCoreMembers()
	{
		Set<Artist> coreMembers = new TreeSet<Artist>();
		boolean first = true;

		for (LineUp lineUp : getLineUps())
			if (first)
			{
				// Add all the artists
				coreMembers.addAll(lineUp.getArtists());
				first = false;
			}
			else
			{
				Collection<Artist> toRemove = new LinkedList<Artist>();
				for (Artist artist : coreMembers)
					if (!lineUp.getArtists().contains(artist))
						toRemove.add(artist);
				coreMembers.removeAll(toRemove);
			}

		return coreMembers;
	}