距离空间中上半连续函数的定义及等价条件

The Definition of Upper Continuity of Function in the Distance Space and its Equivalence Condition

根据距离空间中函数在某点的上极限、下极限的定义及函数在某点上半连续、下半连续的定义,证明了函数在某点上半连续的等价条件.

According to the definition of upper limit and lower limit of function on a certain spot in the distance space,and the definition of upper continuity and lower continuity of function on a certain spot,the article proves the equivalence condition of the upper continuity of function on a certain spot.