private boolean hasEveryIdentityDiscPositionOnlyOneIdentityDisc(Grid grid) {
		List<IdentityDisc> identityDiscs = getIdentityDiscsOfGrid(grid);
		
		for (IdentityDisc idDisc : identityDiscs) {
			final Position idDiscPos = grid.getElementPosition(idDisc);
			
			for (Element e : grid.getElementsOnPosition(idDiscPos))
				if (e instanceof IdentityDisc && e != idDisc)
					return false;
		}
		
		return true;
	}