Imagine a maze with rooms (nodes) and doors (relationships) between the rooms. The doors to some rooms are locked and their keys are held in other rooms (as properties).
In this gist model of the maze, you can reach room D by following the path A→B→C→A, picking up the key for room D in room B. However it is not possible to reach room F, since the key to room F is in room E, and the key to room E is in room D, and there is no way back from room D to room A, so room E is inaccessible. (Finding the HIDDEN door from room D to room C would make this possible.)
Is it possible to create queries which take into account the keys that can be picked up on the way? For example: