1
GATE CSE 2006
MCQ (Single Correct Answer)
+2
-0.6
In the correct grammar of the previous question, what is the length of the derivation (number of steps starring from S) to generate the string $${a^l}{b^m}$$ with $$l \ne m$$?
A
$$\max (l,m) + 2$$
B
$$l + m + 2$$
C
$$l + m + 3$$
D
$$\max (l,m) + 3$$
2
GATE CSE 2005
MCQ (Single Correct Answer)
+2
-0.6

Consider the grammar

$$S \to \left( S \right)\,|\,a$$

Let the number of states in SLR(1), LR(1) and LALR(1) parsers for the grammar be n1, n2 and n3 respectively.

The following relationship holds good
A
n1 < n2 < n3
B
n1 = n3 < n2
C
n1 = n2 = n3
D
n1 ≥ n3 ≥ n2
3
GATE CSE 2005
MCQ (Single Correct Answer)
+2
-0.6

Consider the grammar

$$E \to E + n\,|\,E \times n\,|\,n$$

For a sentence n + n × n, the handles in the right-sentential form of the reduction are

A
n, E + n and E + n × n
B
n, E + n and E + E × n
C
n, n + n and n + n × n
D
n, E + n and E × n
4
GATE CSE 2005
MCQ (Single Correct Answer)
+2
-0.6

Consider the following expression grammar. The seman­tic rules for expression calculation are stated next to each grammar production.

$$\eqalign{ & E \to number\,\,\,\,\,E.val = number.val \cr & \,\,\,\,\,\,\,\,\,\,\,|E\,\,' + '\,\,E\,\,\,\,\,\,{E^{\left( 1 \right)}}.val = {E^{\left( 2 \right)}}.val + {E^{\left( 3 \right)}}.val \cr & \,\,\,\,\,\,\,\,\,\,\,|\,E\,\,' \times '\,\,E\,\,\,\,\,\,\,{E^{\left( 1 \right)}}.val = {E^{\left( 2 \right)}}.val \times {E^{\left( 3 \right)}}.val \cr} $$

Assume the conflicts in the previous question are resolved and an LALR(1) parser is generated for parsing arithmetic expressions as per the given grammar. Consider an expression
3 × 2 + 1.
What precedence and associativity properties does the generated parser realize?

A
Equal precedence and left associativity; ex­pression is evaluated to 7
B
Equal precedence and right associativity; ex­pression is evaluated to 9
C
Precedence of $$' \times '$$ is higher than that of ‘+’, and both operators are left associative; expression is evaluated to 7
D
Precedence of ‘+’ is higher than that of $$' \times '$$, and both operators are left associative; expression is evaluated to 9

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