4.6. Changing the role binding
What if we just remove the binding of role instance R1? A glance at Figure 5 tells us that all queries with the step binder x <R1> should be recomputed, and the queries that contain the step binding R1. This is because we’ve severed a connection between nodes and those are the two kinds of step that traverse this type of link.
Figure 5. Remove the binding of node R1.
If we add a link, we do the same. Now one could wonder: can there be queries that have recorded this step, as they could not traverse the link before? Yes, there could be, because we record such steps, whether they succeed or not. So a query that tries to move from x to an instance of R1 by attempting the step binder x R1, records that step – even if it fails. Similarly, a step from R1 by following its binding records the step binding R1, even when there is no binding at all.