public String[] getVariables() {

		ArrayList list = new ArrayList();
		String[] rhsVariables = getVariablesOnRHS();
		for (int k = 0; k < rhsVariables.length; k++) {
			if (!list.contains(rhsVariables[k])) {
				list.add(rhsVariables[k]);
			}
		}

		String[] lhsVariables = getVariablesOnLHS();
		for (int i = 0; i < lhsVariables.length; i++) {
			if (!list.contains(lhsVariables[i])) {
				list.add(lhsVariables[i]);
			}
		}

		return (String[]) list.toArray(new String[0]);
	}