Companion determining device, companion determining system, companion determining method and computer-readable medium

摘要

A companion determining device determines presence of a companion of a tracked user. The device includes a receiver, a receipt determiner and a presence determiner. The receiver receives a user identifier from an external device via a near-field wireless communication link. The receipt determiner determines whether the receiver has received the user identifier sent from the external device. The presence determiner determines presence of a companion acting with the tracked user based on determination by the receipt determiner.