The question asks to identify the false statement among the given options related to formal grammars and parsing techniques.
Analyzing Parsing Technique Statements
Statement 1: Grammar Ambiguity
The grammar given is $S \rightarrow a Sb | b Sa | SS | \epsilon$. This grammar generates strings where the count of 'a's equals the count of 'b's. Grammars containing the $SS$ rule alongside rules like $aSb$ or $bSa$ are often ambiguous. For example, deriving strings like "aabb" can potentially be done in multiple ways, making the statement that this grammar is ambiguous likely true.
Statement 2: SLR vs LALR Power
This statement claims that SLR (Simple LR) is more powerful than LALR (Look-Ahead LR). In reality, the relationship is reversed. LALR is a more refined parsing technique derived from SLR. LALR parsers can handle a larger set of deterministic context-free grammars compared to SLR parsers. Therefore, LALR is considered more powerful than SLR. The statement "SLR is powerful than LALR" is factually incorrect.
Statement 3: LL(1) Parser Type
An LL(1) parser is defined as a parser that reads the input string from left-to-right (L), produces a left-most derivation (L), and uses one lookahead symbol. This description inherently classifies it as a top-down parsing method. Thus, this statement is true.
Statement 4: YACC Tool
YACC (Yet Another Compiler Compiler) is a standard tool used in compiler construction. Its primary function is to generate a parser based on a given grammar specification. YACC specifically generates LALR(1) parsers. Hence, this statement is true.
Conclusion
Based on the analysis, the false statement is that SLR is more powerful than LALR.
Correct Option: B
Important Questions from Automata Theory Concepts - Teaching
- Match List I with List II
List I List II A. Type 3 Grammar I. V $\rightarrow$ (V $\cup$$\Sigma$)* B. Type 2 Grammar II. $\lambda$V$\beta$ $\rightarrow$ $\lambda$(V $\cup$$\Sigma$)*$\beta$, where ($\lambda$,$\beta$)$\epsilon$(V $\cup$$\Sigma$)* C. Type 1 Grammar III. (V $\cup$$\Sigma$)* $\rightarrow$ (V $\cup$$\Sigma$)* D. Type 0 Grammar IV. V $\rightarrow$ V$\Sigma$|$\Sigma$
Choose the correct answer from the options given below: Match the following :
List – I List – II a. Context free grammar i. Linear bounded automaton b. Regular grammar ii. Pushdown automaton c. Context sensitive grammar iii. Turing machine d. Unrestricted grammar iv. Deterministic finite automaton Codes :
a b c d
Given the recursively enumerable language (\(L_{RE}\)), the context sensitive language (\(L_{CS}\)), the recursive language (\(L_{REC}\)), the context free language (\(L_{CF}\)) and deterministic context free language (\(L_{DCF}\)). The relationship between these families is given by
The family of context sensitive languages is __________ under union and __________ under reversal.
Match the LIST-I with LIST-II
LIST-I LIST-II A. Type - 0 grammar I. Linear Grammar B. Type - 1 grammar II. GNF C. Type - 2 grammar III. x→y, |x|<|y|; x, y ∈ {V ∪ T}* D. Type - 3 grammar IV. Recursively Enumerable Choose the correct answer from the options given below:
