Determination system, integrated system, determination method, and program

A determination method comprising:

• an acquisition step including acquiring schedule information representing multiple time slots, in each of which any number of persons are present in, or absent from, a space;
• an estimation step including estimating, by reference to the schedule information, how many persons are supposed to be present in the space to obtain an estimated number of persons;
• a detection step including detecting, based on a result of detection provided by a sensor installed in the space to detect any human beings, how many persons are present in the space to obtain a detected number of persons;
• and
• a determination step including comparing the estimated number of persons with the detected number of persons to determine, based on a result of comparison, whether a current condition in the space is an abnormal condition where abnormality has occurred in the space,
• the determination step including, when the result of comparison indicates that the estimated number of persons disagrees with the detected number of persons, determining the current condition in the space to be the abnormal condition.