One embodiment of the present invention is a method for determining when a set of RFID tags on a set of stacked objects belongs to a same defined subset of stacked objects (“set identification”). This method includes the steps of: (1) detecting the set of RFID tags on the set of stacked objects, said RFID tags comprising integrated devices capable of sending signals that can be received by a receptor device and interpreted to determine a motion state of each RFID tag and stacked object; (2) receiving said signals from the set of RFID tags; (3) interpreting said signals to determine the motion state of each RFID tag and stacked object within the set, wherein said signals indicate whether the motion state of each RFID tag and object is in a state of stationary, starting in motion, stopping in motion, or continuing in motion; (4) determining which RFID tags and objects are in a same motion state within a predetermined time of each other; and (5) identifying the RFID tags that are in the same motion state, within the predetermined time, as belonging to the same defined subset of stacked objects, wherein said motion state is used to determine when said set of stacked objects forms a new stack.