GATE CSE 2005
Q41.
Let r be a relation instance with schema R = (A, B, C, D). We define r_{1}=\Pi _{A,B,C}(R) and r_{2}=\Pi _{A,D}(R). Let s=r_1*r_2 where * denotes natural join. Given that the decomposition of r into r_1 and r_2 is lossy, which one of the following is TRUE?Q42.
Consider a relation scheme R=(A,B,C,D,E,H) on which the following functional dependencies hold: {A\rightarrowB, BC\rightarrowD, E\rightarrowC, D\rightarrowA}. What are the candidate keys of R?Q43.
Let R and S be any two equivalence relations on a non-empty set A. Which one of the following statements is TRUE?Q44.
Let A, B and C be non-empty sets and let X = (A - B) - C and Y = (A - C) - (B - C) Which one of the following is TRUE?Q45.
Let s and t be two vertices in a undirected graph G=(V, E) having distinct positive edge weights. Let [X, Y] be a partition of V such that s\inX and t\inY. Consider the edge e having the minimum weight amongst all those edges that have one vertex in X and one vertex in Y. Let the weight of an edge e denote the congestion on that edge. The congestion on a path is defined to be the maximum of the congestions on the edges of the path. We wish to find the path from s to t having minimum congestion. Which one of the following paths is always such a path of minimum congestion?Q46.
Let G(V,E) be an undirected graph with positive edge weights. Dijkstra's single source shortest path algorithm can be implemented using the binary heap data structure with time complexity:Q47.
The relation book (title, price) contains the titles and prices of different books. Assuming that no two books have the same price, what does the following SQL query list? select title from book as B where (select count(*) from book as T where T.price > B.price) < 5Q48.
Consider the following code fragment: if (fork() == 0) { a = a + 5; printf("%d,%dn", a, &a); } else { a = a - 5; printf("%d, %dn", a, &a); } Let u, v be the values printed by the parent process, and x, y be the values printed by the child process. Which one of the following is TRUE?Q50.
Consider three decision problems P1, P2 and P3. It is known that P1 is decidable and P2 is undecidable. Which one of the following is true?