private static function greekLargerThan($greek1, $greek2)
    {
        // If they do not exist as valid precendence identifiers assume
        // bigger/smaller based on that
        if (!in_array($greek1, self::$greekPrecendence)) {
            return true;
        }
        if (!in_array($greek2, self::$greekPrecendence)) {
            return false;
        }

        // Use the index in precendence for comparison
        return
            array_search($greek1, self::$greekPrecendence)
            >
            array_search($greek2, self::$greekPrecendence);
    }