Consider the following two transactions :

t1:

read(a);

read(b);

if a = 0 then b : = b + 1;

write(b).

t2:

read(b);

read(a);

if b = 0 then a : = a + 1;

write(a).

a- add lock and unlock instructions to transactions t1 and t2, so that they observe the two-phase locking protocol.

use the lock-s and lock-x notation as defined below:

-shared lock.

if a transaction t has obtained a shared-mode lock (denotedby lock-s) on item q, thent can read, but cannot write, q. 2.

-exclusive lock.

if a transaction t has obtained an exclusive-mode lock (denoted by lock-x) on item q, thent can both read and write q.

b- can the execution of these transactions result in a deadlock? give an example if it can. write all the details.