GATE CSE 2016 SET-2
Q52.
Consider the following database table named water_schemes : The number of tuples returned by the following SQL query is __________.Q53.
Suppose a database schedule S involves transactions T1,...,Tn. Construct the precedence graph of S with vertices representing the transactions and edges representing the conflicts. If S is serializable, which one of the following orderings of the vertices of the precedence graph is guaranteed to yield a serial schedule?Q54.
Consider the following databases chedule with two transactions, T1 and T2. S=r_{2}(X);r_{1}(X);r_{2}(Y);w_{1}(X);r_{1}(Y);w_{2}(X);a_{1};a_{2} where r_{i}(Z) denotes a read operation by transaction T_{i} on avariable Z, w_{i}(Z) denotes a write operation by T_{i} on avariable Z and a_{i} denotes an abort by transaction T_{i}. Which one of the following statements about the above schedule is TRUE?Q55.
Consider the following languages. L1 = {\ltM\gt |M takes at least 2016 steps on some input}, L2 = {\ltM\gt| M takes at least 2016 steps on all inputs g} and L3 = {\ltM|M accepts \varepsilon}, where for each Turing machine M, \ltM\gt denotes a specific encoding of M. Which one of the following is TRUE?