Professor Przlwytszkowsky writes: "Reading Chapter 10 improved my understanding of the algorithms of Chapter 8. In Safra's algorithm (Algorithm 8.7), for example, the handling of the token by p should...

Professor Przlwytszkowsky writes:

"Reading Chapter 10 improved my understanding of the algorithms of Chapter 8. In Safra's algorithm (Algorithm 8.7), for example, the handling of the token by p should be seen as defining p's snapshot state. In the constructed snapshot all processes are passive, because the token is only handled by passive processes. So the computation of Pholds only requires a check of whether all channels are empty, to which end the token collects the sum of the message counts.

I do not understand, however, the role of the colors white and black, and how the meaningfulness of the snapshot is guaranteed. "

Can you help the professor?