When conference conditions are set by a conference sponsor, a conference sponsor agent inquires of schedule management agents of requested attendants about available time within a range of set dates, determines an optimum conference schedule on the basis of the available time of the individual requested attendants, sends to the conference sponsor the conference schedule for confirmation thereof, and sends a conference notification to the requested attendants. In order to permit an input value set by a user to have a range in accordance with the kind of parameter requiring the input value and conditions at that time, an input value acquiring element acquires an input value of a parameter necessary for a processing realized by an application element, the input value being set by the user by an input element. An allowable value determining element determines an allowable value to be added to the input value on the basis of information supplied from the application element and corresponding to the kind of the parameter and conditions at that time, and an allowable value adding element determines a different input value from the acquired input value by adding the allowable value to the acquired input value and delivers the acquired input value and the thus determined different input value, as input values of the parameter, to the application element.