Broadcast and Aggregation in BBC

In this paper we introduce a process calculus BBC that has both forms of communication. For both many-to-one and one-to-many communication, it is often a natural assumption that communication is bounded; this reflects two distinct aspects of the limitations of a medium. In the case of broadcast, the bound limits the number of possible recipients of a message. In the case of collection, the bound limits the number of messages that can be received. For this reason, BBC uses a notion of bounded broadcast and collection. Moreover, the syntax of the calculus introduces an explicit notion of connectivity that makes it possible to represent a communication topology directly. By using a proof technique introduced by Palamidessi we show that even a version of BBC that only uses collection is more expressive than the pi-calculus.