How to pass signals within loops?
Problem: Consider a stage with two input ports and two output ports. One of its output port is connnected with one of its input port. Thus, this stage contains a loop. If now the stage's semantics is defined to pass the termination signal only when it was received from each input port, this stage will never terminate because the input port with the loop will never receive the terminate signal. The same problem arises when the loop extends over more than a single stage.