public String getNewVariableThatBelongsInLambdaSet(Grammar grammar,
			Set lambdaSet) {
		String[] variables = grammar.getVariables();
		for (int k = 0; k < variables.length; k++) {
			if (!isInLambdaSet(variables[k], lambdaSet)
					&& belongsInLambdaSet(variables[k], grammar, lambdaSet))
				return variables[k];
		}
		return null;
	}