ISRO Scientist or Engineer Computer Science Dec 2017

Instructions

For the following questions answer them individually

ISRO Scientist or Engineer Computer Science Dec 2017 - Question 21


For $$\sum = \left\{a, b\right\}$$ the regular expression $$r = (aa) * (bb) * b$$ denotes

Video Solution

ISRO Scientist or Engineer Computer Science Dec 2017 - Question 22


Consider the grammar with productions
$$S \rightarrow aSb \mid SS \mid ε$$
This grammar is

Video Solution

ISRO Scientist or Engineer Computer Science Dec 2017 - Question 23


Identify the language generated by the following grammar
$$S \rightarrow AB$$
$$A \rightarrow aAb \mid ε$$
$$B \rightarrow bB \mid b$$

Video Solution

ISRO Scientist or Engineer Computer Science Dec 2017 - Question 24


Let $$L_1$$ be regular language, $$L_2$$ be a deterministic context free language and $$L_3$$ a recursively enumerable language, but not recursive. Which one of the following statements is false?

Video Solution

ISRO Scientist or Engineer Computer Science Dec 2017 - Question 25


Let $$L = \left\{a^p \mid p is a prime \right\}$$. Then which of the following is true

Video Solution

ISRO Scientist or Engineer Computer Science Dec 2017 - Question 26


Which of the following are context free?
$$A = \left\{a^nb^n a^mb^m \mid m, n \geq 0\right\}$$
$$B = \left\{a^mb^n a^mb^n \mid m, n \geq 0\right\}$$
$$C = \left\{a^mb^n\mid m \neq 2n, m, n \geq 0\right\}$$

Video Solution

ISRO Scientist or Engineer Computer Science Dec 2017 - Question 27


Let S be an NP-complete problem. Q and R are other two problems not known to be NP. Q is polynomial time reducible to S and S is polynomial time reducible to R. Which of the
following statements is true?

Video Solution

ISRO Scientist or Engineer Computer Science Dec 2017 - Question 28


The number of structurally different possible binary trees with 4 nodes is

Video Solution

ISRO Scientist or Engineer Computer Science Dec 2017 - Question 29


Using public key cryptography, X adds a digital signature σ to a message M, encrypts $$\langle M, \sigma \rangle$$ and sends it to Y, where it is decrypted. Which one of the following sequence of keys is used for operations?

Video Solution

ISRO Scientist or Engineer Computer Science Dec 2017 - Question 30


Which of the following are used to generate a message digest by the network security protocols?
(P) SHA-256
(Q) AES
(R) DES
(S) MD5

Video Solution
cracku

Boost your Prep!

Download App