An instantaneous description formally describes the state of a CP instance at a particular time. An instantaneous description of a CP instance is a 7-tuple:
is the originator agent; is the helper agent; is the polarity of the CP instance; is the current setting of transport policies; is the current state of the finite state control; represents all utterances currently kept by the input list; and is the current state of the pushdown list.
Figure 3 depicts a partial instantaneous description for an instance of the CP DBP employed by a trading interagent to allow its customer (a buyer agent) to participate in a bidding round open by the auctioneer agent. We identify buyer Akira as the originator, the auctioneer as the helper, and the colored node as the state of the finite state control.
A deterministic CP has at most --without taking into account possible e-moves for dealing with expired utterances-- one possible move from any instantaneous description. However, continuously traversing the input list in search of an utterance that causes a transition can lead to race conditions. For instance, in the CP instance of Figure 3 the second and fourth utterances can originate a race condition since both utterances can cause a move in the finite state control. Thus, it is necessary to define criteria for deciding which utterance must be accepted as we show in the next section.