In the wait-free protocol, a thread adds its newly appended node to the head[]array on line28even though it may have already added it on line26.Thisisdone because, unlike in the lock-free protocol, it...

In the wait-free protocol, a thread adds its newly appended node to the head[]array on line28even though it may have already added it on line26.Thisisdone because, unlike in the lock-free protocol, it could be that the thread’s node was added by another thread on line26, and that “helping” thread stopped at line26rightafter updating the node’s sequence number but before updating the head []array.

1. Explain how removing line28would violate Lemma6.4.4.

2. Would the algorithm still work correctly?