ACP with Signals

New operators are introduced on top of ACP [BK 84] in order to incorporate stable signals in process algebra. Semantically this involves assigning labels to nodes of process graphs. The labels of nodes are called signals. In combination with the operators of BPA, a signal insertion operator allows to describe each finite tree labeled with actions and signals, provided the signals do not occur at leaves of the tree. In a merge processes can observe the signals of concurrent processes. This research was sponsored in part by ESPRIT under contract 432, METEOR.