UGC-NET | UGC NET CS 2014 Dec – II | Question 35

The following Context-Free Grammar (CFG):
S → aB | bA
A → a | aS | bAA
B → b | bS | aBB
will generate
(1) odd numbers of a’s and odd numbers of b’s
(2) even numbers of a’s and even numbers of b’s
(3) equal numbers of a’s and b’s
(4) different numbers of a’s and b’s
(A) (1)
(B) (2) an (3)
(C) (1), (2) and (3)
(D) All are correct.


Answer: (D)

Explanation: The following Context-Free Grammar (CFG):
S → aB | bA
A → a | aS | bAA
B → b | bS | aBB
will generate

odd numbers of a’s and odd numbers of b’s i.e. ab or ba.

even numbers of a’s and even numbers of b’s i.e. aabb or bbaa

equal numbers of a’s and b’s i.e.ab, ba bbaa or aabb

different numbers of a’s and b’s i.e. abb or baa.

Option (D) is correct.

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