Theory of Computation and Compilers MCQ - Syntax Analysis

21 Consider the grammar given below:
S → Aa
A → BD
B → b|ε
D → d|ε
Let a, b, d, and $ be indexed a follows:

a	b	d	$
3	2	1	0

Compute the FOLLOW set of the non-terminal B and write the index values for the symbols in the FOLLOW set in the descending order. (For example, if the FOLLOW set is {a, b, d, $), then the answer should be 3210)

S → Aa
A → BD
B → b|ε
D → d|ε
Follow (B) = {d, a}
Hence index value in descending order is 31.

22 Which of the following statements is true?

LR is power ful than LALR parsers and LALR are power ful than SLR parsers.

23 Assume that the SLR parser for a grammar G has n₁ states and the LALR parser for G has n₂ states. The relationship between n₁ and n₂ is

Number of st at e in SLR is always same as number of st ate in LALR parser.

24 Consider the grammar shown below
S → i E t S S'|α
S' → eS | ε
E → b
In the predictive parse table M, of this grammar, the entries M[S', e] and M[S', $] respectively are

S → iE tSS¹\a
S' ⇒ eS|a
E → b
This is left factor grammar
Thus we may expand S to ibtSS' on input i and wait untill ibtS has been seen to decide whether to expand S' → eS|∈

25 Which of the following grammar rules violate the requirements of an operator grammar?
P, Q, R are not terminals and r, s, t are terminals.
(i) P → Q R
(ii) P → Q s R
(iii) P → ε
(iv) P → Q t R r

P → QR and P → ε is not possible for operator grammar.