Q. 23 Suppose the adjacency relation of vertices in a graph is represented in a table Adj(X,Y). Which of the following queries cannot be expressed by a relational algebra expression of constant length?
(A) List of all vertices adjacent to a given vertex
(B) List all vertices which have self loops
(C) List all vertices which belong to cycles of less than three vertices
(D) List all vertices reachable from a given vertex
Answer: (D)
Explanation:
