Methods and apparatus for performing specified actions when the relative position of specified objects satisfies conditions specified by a user and expressed in one or more rules. Each of the rules contains a condition part and an action part. The condition part of each rules specifies one or more conditions that are satisfied when specified objects move into or out of a predetermined range of one another. Each rule further contains an action part which specifies a function to be performed when the condition part of the rule is satisfied. The relative positions of objects are determined by an electronic interrogation device which can determine the identity of other electronic devices that are within range of the interrogation device. The electronic interrogation devices and the identification devices may be implemented using Bluetooth compliant devices, RFID tags and tag readers, or GPS devices.