1
GATE CSE 1996
Subjective
+2
-0
Let $$G$$ be a context free grammar where $$G = \left( {\left\{ {S,A,.B,C} \right\},\left\{ {a,b,d} \right\},P,S} \right)$$ with productions $$P$$ given below
$$\eqalign{ & S \to ABAC\,\,\,\,\,\,\,\,\,S \to aA{\mkern 1mu} \left| \varepsilon \right. \cr & S \to bB{\mkern 1mu} \left| \varepsilon \right.\,\,\,\,\,\,\,\,\,\,\,\,\,\,C \to d \cr} $$

($$\varepsilon $$ denotes the null string). Transform the given grammar $$G$$ to an equivalent context- free grammar $${G^1}$$ that has no $$\varepsilon $$ productions ($$A$$ unit production is of the from $$x \to y,\,x$$ and $$y$$ are non terminals).

2
GATE CSE 1994
MCQ (Single Correct Answer)
+2
-0.6
Which of the following features cannot be captured by context-free grammars?
A
Syntax of if-then-else statements
B
Syntax of recursive procedures
C
Whether a variable has been declared before its use
D
Variable names of arbitrary length
3
GATE CSE 1992
MCQ (More than One Correct Answer)
+2
-0.6
Context-free languages are
A
closed under union
B
closed under complementation
C
closed under intersection
D
closed under Kleene closure.
4
GATE CSE 1989
MCQ (More than One Correct Answer)
+2
-0.6
Context free languages and regular languages are both closed under the operation(s) of :
A
Union
B
Intersection
C
Concatenation
D
Complementation
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