1. A dialog apparatus comprising: a dialog unit configured to perform a dialog with a user and to collect a plurality of items to be referred to in accordance with the dialog as the dialog continues; a dividing unit configured to divide the items into normal items related to any usable application and unusable items related to any unusable application; a managing unit configured to manage the normal items and the unusable items which the dialog unit refers to during the dialog with the user; a detecting unit configured to detect whether or not one of the normal items managed by the managing unit is changed to be unusable, and to change the one of the normal items into an unusable item; and a referring unit configured to refer to the managing unit in accordance with the items collected by the dialog unit and to determine to output a use-disapproval notice when it is determined that the collected items include at least one unusable item related to an unusable application, wherein the dialog unit outputs the use-disapproval notice based on a result determined by the referring unit.
1. A dialog apparatus comprising: a dialog unit configured to perform a dialog with a user and to collect a plurality of items to be referred to in accordance with the dialog as the dialog continues; a dividing unit configured to divide the items into normal items related to any usable application and unusable items related to any unusable application; a managing unit configured to manage the normal items and the unusable items which the dialog unit refers to during the dialog with the user; a detecting unit configured to detect whether or not one of the normal items managed by the managing unit is changed to be unusable, and to change the one of the normal items into an unusable item; and a referring unit configured to refer to the managing unit in accordance with the items collected by the dialog unit and to determine to output a use-disapproval notice when it is determined that the collected items include at least one unusable item related to an unusable application, wherein the dialog unit outputs the use-disapproval notice based on a result determined by the referring unit. 15. The apparatus according to claim 1 , wherein the items are topics.