Question: Consider the following graph-based locking protocol, which allows only exclusive lock modes, and which operates on data graphs that are in the form of a

Consider the following graph-based locking protocol, which allows only exclusive lock modes, and which operates on data graphs that are in the form of a rooted directed acyclic graph.

• A transaction can lock any vertex first.

• To lock any other vertex, the transaction must be holding a lock on the majority of the parents of that vertex. Show that the protocol ensures serializability and deadlock freedom.

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