Database-Management-System
February 13, 2024Question 9849 – Minimum-Spanning-Tree
February 13, 2024Database-Management-System
| Question 49 |
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?
| List of all vertices adjacent to a given vertex | |
| List all vertices which have self loops | |
| List all vertices which belong to cycles of less than three vertices | |
| List all vertices reachable from a given vertex |
Question 49 Explanation:
(a) Finding a adjacency vertex for the given vertex is too simple i.e., Adj(X,Y).
(b) Finding a self loop is also simple (Oop(X,X))
(c) If a → b, b → c then c!=a, finding this is also simple.
(d) List all the elements reachable from a given vertex is too difficult in Relational Algebra.
(b) Finding a self loop is also simple (Oop(X,X))
(c) If a → b, b → c then c!=a, finding this is also simple.
(d) List all the elements reachable from a given vertex is too difficult in Relational Algebra.
Correct Answer: D
Question 49 Explanation:
(a) Finding a adjacency vertex for the given vertex is too simple i.e., Adj(X,Y).
(b) Finding a self loop is also simple (Oop(X,X))
(c) If a → b, b → c then c!=a, finding this is also simple.
(d) List all the elements reachable from a given vertex is too difficult in Relational Algebra.
(b) Finding a self loop is also simple (Oop(X,X))
(c) If a → b, b → c then c!=a, finding this is also simple.
(d) List all the elements reachable from a given vertex is too difficult in Relational Algebra.
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