Does the plan using the pointer fields of the original node guarantee that the threads for all predecessors will be recorded? There exist situations where a node has a left child and thus its...

Does the plan using the pointer fields of the original node guarantee that the threads for all predecessors will be recorded?

There exist situations where a node has a left child and thus its predecessor cannot be recorded, for example, node E in →Fig. 1.68, which does not have a pointer field to record the address of its predecessor D. However, note that for pre-order traversal, it suffices to have the thread for the successor of a node. Therefore, even when there is some “gap” in the threads for the predecessor, it does not impact the operation of pre-order traversal.