ABSTRACT
We now consider a different strategy of cooperation in a distributed system of grammars, a different type of activity protocol. So far, the components of the systems worked sequentially, in each moment one being active and all the others being inactive and the communication between them being realized by the common sentential form. Now, we consider the components working simultaneously, not rewriting the same string (this would be, in fact, a purely parallel manner of rewriting), but each having its own sentential form. A minimal synchronization of the components is assumed, namely by means of an universal clock, the same for the whole system, which divides the time into units and each component has to do an elementary rewriting (to use a rule) in each time unit. In order to have a real system, the components have to cooperate in some way in solving a common task. This is accomplished by communication, and a communication means to transmit messages, parts of the current sentential forms, from one component to another. A communication can be asked either by the receiver of the message (it needs, partially or totally, the sentential form of a co-worker), or by the message sender. Here we shall investigate only the first case, when the communication is done by request: in certain moments, certain components can request the whole string generated by another component (maybe it can request at the same time the strings generated by more partners); this query is immediately satisfied.
