public String[] getVariablesOnLHS() {
		ArrayList list = new ArrayList();
        if(myLHS == null) return new String[0];
		for(int i = 0; i < myLHS.length(); i++) {
			char c = myLHS.charAt(i);
			if (ProductionChecker.isVariable(c))
				list.add(myLHS.substring(i, i + 1));
		}
		return (String[]) list.toArray(new String[0]);
	}