[] means including the left and right endpoint values; [) indicates that the left endpoint value is included, but the endpoint value is not included. In the interval symbol representation in mathematics, [] means including left and right endpoint values; [) indicates that the left endpoint value is included, but the endpoint value is not included; (] means including the right end point value, but excluding the left end point value; () means that the left and right endpoint values are not included, and the left and right endpoint values are separated by commas.