Consider the following two transactions:

T1: read (A); read (B); if A = 0then B: = B + 1; write (B).

T2: read (B); read (A); if B = 0 then A: = A + 1; write (A).

Let the consistency requirement be A = 0 ∨ B = 0, with A = B = 0 the initial values.

a. Show that every serial execution involving these two transactions preserves the consistency of the database.

b. Show a concurrent execution of T1 and T2 that produces a nonserializable schedule.

c. Is there a concurrent execution of T1 and T2 that produces a serializable schedule?