GATE CSE 2012
Q41.
Which of the following statements are TRUE about an SQL query? P : An SQL query can contain a HAVING clause even if it does not have a GROUP BY clause Q : An SQL query can contain a HAVING clause only if it has a GROUP BY clause R : All attributes used in the GROUP BY clause must appear in the SELECT clause S : Not all attributes used in the GROUP BY clause need to appear in the SELECT clauseQ42.
A process executes the code fork(); fork(); fork(); The total number of child processes created isQ43.
Consider the following transactions with data items P and Q initialized to zero: T1 :read (P); read (Q); if P = 0 then Q := Q + 1 ; write (Q). T2 : read (Q); read (P); if Q = 0 then P := P + 1 ; write (P). Any non-serial interleaving of T1 and T2 for concurrent execution leads toQ44.
Which of the following transport layer protocols is used to support electronic mail?Q45.
Consider an instance of TCP's Additive Increase Multiplicative Decrease (AIMD) algorithm where the window size at the start of the slow start phase is 2 MSS and the threshold at the start of the first transmission is 8 MSS. Assume that a timeout occurs during the fifth transmission. Find the congestion window size at the end of the tenth transmission.Q46.
Which of the following problems are decidable? 1) Does a given program ever produce an output? 2) If L is a context-free language, then, is \bar{L} also context-free? 3) If L is a regular language, then, is \bar{L} also regular? 4) If L is a recursive language, then, is \bar{L} also recursive?