Subject: Effects of changing the dependencies of the subsystem decomposition

> If we consider the database management system as the lowest layer, will
> that be considered a layer below the Environment subsystem?

There would be 4 layers rather than just 3.  The Database Management subsystem
then appears by itself on the lowest layer.

> Because we will have Communication, Sensor and Positioning System as the
> 3rd layer. And if we consider the database layer as the last layer that is
> the 4th layer, then the Environment will be jumping from 2nd layer to the
> 4th layer. Am I thinking correctly?

Yes, it does jump.  Thus you would have an open rather than a closed layering
structure in these layers.