Recent questions tagged ambiguous

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Ullman (Compiler Design) Edition 2 Exercise 4.8 Question 1 (Page No. 285 - 286)
The following is an ambiguous grammar for expressions with $n$ binary, infix operators, at $n$ ... ambiguous and unambiguous) grammars compare? What does that comparison tell you about the use of ambiguous expression grammars?

asked 1 day ago in Compiler Design by Lakshman Patel RJIT Boss (45.1k points) | 1 view

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Ullman (Compiler Design) Edition 2 Exercise 4.3 Question 3 (Page No. 217)
The following grammar is proposed to remove the "danglingelse ambiguity" discussed in Section $4.3.2$: $stmt\rightarrow if\: expr\: then\: stmt\mid matchedstmt$ $matchedstmt \rightarrow if \:expr \:then \:matchedstmt\: else\: stmt\mid other$ Show that this grammar is still ambiguous.

asked 1 day ago in Compiler Design by Lakshman Patel RJIT Boss (45.1k points) | 1 view

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Ullman (Compiler Design) Edition 2 Exercise 4.2 Question 2 (Page No. 206 - 207)
Repeat Question $4.2.1$ for each of the following grammars and strings: $S\rightarrow 0S1\mid 01$ with string $000111$. $S\rightarrow +SS\mid \ast SS\mid a$ with string $+\ast aaa$ ... $bfactor\:\rightarrow\:not\:bfactor\mid (bexpr)\mid true\mid false$

asked 4 days ago in Compiler Design by Lakshman Patel RJIT Boss (45.1k points) | 5 views

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Ullman (Compiler Design) Edition 2 Exercise 4.2 Question 1 (Page No. 206)
Consider the context-free grammar:$S\rightarrow SS + \mid SS {\ast} \mid a$and the string $aa + a{\ast}$. Give a leftmost derivation for the string. Give a rightmost derivation for the string. ... for the string. Is the grammar ambiguous or unambiguous? Justify your answer. Describe the language generated by this grammar.

asked Aug 7 in Compiler Design by Lakshman Patel RJIT Boss (45.1k points) | 28 views

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Ullman (Compiler Design) Edition 2 Exercise 2.2 Question 3 (Page No. 51)
Which of the grammars are ambiguous? $S\rightarrow 0S1 \mid 01$ $S\rightarrow +SS \mid -SS \mid a$ $S\rightarrow S(S)S \mid \epsilon$ $S\rightarrow aSbS \mid bSaS \mid \epsilon$ $S\rightarrow a \mid S+S \mid SS \mid S^{\ast} \mid (S)$

asked Jul 26 in Compiler Design by Lakshman Patel RJIT Boss (45.1k points) | 17 views

+1 vote

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Self Doubt : Ambiguity
Why is ambiguity in regular language is decidable and not decidable in CFL ? Can you give Example?

asked May 10 in Theory of Computation by logan1x (399 points) | 109 views

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Michael Sipser Edition 3 Exercise 2 Question 9 (Page No. 155)
Give a context-free grammar that generates the language $A=\{a^{i}b^{j}c^{k}\mid i=j$ $\text{or}$ $ j=k$ $\text{where}$ $ i,j,k\geq 0\}.$ Is your grammar ambiguous$?$ Why or why not$?$

asked May 1 in Theory of Computation by Lakshman Patel RJIT Boss (45.1k points) | 13 views

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Peter Linz Edition 4 Exercise 5.2 Question 19 (Page No. 145)
Prove the following result. Let $G = (V, T, S, P )$ be a context-free grammar in which every $A ∈ V$ occurs on the left side of at most one production. Then $G$ is unambiguous.

asked Apr 14 in Theory of Computation by Naveen Kumar 3 Boss (14k points) | 13 views

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Peter Linz Edition 4 Exercise 5.2 Question 18 (Page No. 145)
Is the string $aabbababb$ in the language generated by the grammar $S → aSS|b$? Show that the grammar with productions $S\rightarrow aAb|\lambda,$ $A\rightarrow aAb|\lambda$ is unambiguous.

asked Apr 14 in Theory of Computation by Naveen Kumar 3 Boss (14k points) | 17 views

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Peter Linz Edition 4 Exercise 5.2 Question 16 (Page No. 145)
Show that the grammar with productions $S\rightarrow aAB,$ $A\rightarrow bBb,$ $B\rightarrow A|\lambda.$ is unambiguous.

asked Apr 14 in Theory of Computation by Naveen Kumar 3 Boss (14k points) | 23 views

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Peter Linz Edition 4 Exercise 5.2 Question 15 (Page No. 145)
Show that the grammar with productions $S\rightarrow SS,$ $S\rightarrow \lambda,$ $S\rightarrow aSb,$ $S\rightarrow bSa.$ is ambiguous.

asked Apr 14 in Theory of Computation by Naveen Kumar 3 Boss (14k points) | 32 views

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Peter Linz Edition 4 Exercise 5.2 Question 14 (Page No. 145)
Show that the grammar $S\rightarrow aSb|SS|\lambda$ is ambiguous, but that the language denoted by it is not.

asked Apr 14 in Theory of Computation by Naveen Kumar 3 Boss (14k points) | 16 views

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13

Peter Linz Edition 4 Exercise 5.2 Question 13 (Page No. 145)
Show that the following grammar is ambiguous. $S\rightarrow aSbS|bSaS|\lambda$

asked Apr 14 in Theory of Computation by Naveen Kumar 3 Boss (14k points) | 15 views

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14

Peter Linz Edition 4 Exercise 5.2 Question 11 (Page No. 145)
Is it possible for a regular grammar to be ambiguous?

asked Apr 14 in Theory of Computation by Naveen Kumar 3 Boss (14k points) | 13 views

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15

Peter Linz Edition 4 Exercise 5.2 Question 7 (Page No. 145)
Construct an unambiguous grammar equivalent to the grammar in Exercise 6.

asked Apr 14 in Theory of Computation by Naveen Kumar 3 Boss (14k points) | 18 views

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16

Peter Linz Edition 4 Exercise 5.2 Question 6 (Page No. 145)
Show that the following grammar is ambiguous. $S\rightarrow AB|aaB,$ $A\rightarrow a|Aa,$ $B\rightarrow b.$

asked Apr 14 in Theory of Computation by Naveen Kumar 3 Boss (14k points) | 14 views

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17

Peter Linz Edition 4 Exercise 5.2 Question 4 (Page No. 145)
Show that every s-grammar is unambiguous.

asked Apr 14 in Theory of Computation by Naveen Kumar 3 Boss (14k points) | 8 views

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18

DFA NFA and ambiguity
Why is Regular grammar obtained from DFA always unambiguous? Why Regular grammar obtained from NFA may or may not be ambiguous?

asked Dec 7, 2018 in Theory of Computation by OneZero Active (2.1k points) | 45 views

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19

Doubt in Grammar
Consider the following grammar which of the following is/are ambiguous? (i) S → y | SxS (ii) S → E | ExS and E → y (iii) S → Sxy | y

asked Sep 11, 2018 in Theory of Computation by goluabhinan (55 points) | 51 views

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20

UGC NET DEC 2017 PAPER 2 Q 34-
Which of the following statements is/are TRUE ? (i) The grammar S → SS | a is ambiguous (where S is the start symbol). (ii) The grammar S → 0S1 | 01S | e is ambiguous (the special symbol e represents the empty string and S is the start symbol). (iii) The grammar ... TRUE (D) All of (i), (ii) and (iii) are TRUE Sure shot (i) and (ii) are true i want third one in brief

asked Jun 19, 2018 in Compiler Design by Nikhil Patil (489 points) | 263 views

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21

Compiler design
Hi mates, Show that it is ambiguous grammar TIA S->aAB/bBA A->bS/a B->aS/b

asked Nov 24, 2017 in Compiler Design by Sahil1994 Junior (903 points) | 74 views

+1 vote

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22

UGCNET-Nov2017-ii-34
Which of the following statements is/are TRUE ? (a) The grammar $S \rightarrow SS\ |\ a$ is ambiguous. (Where $S$ is the start symbol) (b) The grammar $S \rightarrow 0S1\ |\ 01S\ |\ \epsilon$ is ambiguous. (The special symbol $\epsilon$ represents the empty string) (Where $S$ is the ... and (c) are TRUE. $(3)$ Only (b) and (c) are TRUE. $(4)$ All of (a), (b) and (c) are TRUE.

asked Nov 5, 2017 in Theory of Computation by Arjun Veteran (416k points) | 1k views

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23

Ambiguity
Ques. S --> Aa/bAc/dc A --> d Isn't this grammar Ambiguous? If First(S) has more than one production giving the same first value, isn't it ambiguous?

asked Aug 22, 2017 in Compiler Design by Warlock lord Active (3.2k points) | 78 views

+2 votes

1 answer

24

REGULAR OR NOT
As given that 1st is not regular and 2nd is regular as 1st not form AP but 2nd form.but if in 2nd we fix value of m and n same then it will work as 1st(not regular) so 2nd also should not be regular.as i know if we fix m or n value as any constant it will be AP but what if same???

asked Aug 8, 2017 in Theory of Computation by learner_geek Active (3.1k points) | 244 views

+2 votes

1 answer

25

REGULAR OR NOT
Please mention reason with answer:-

asked Aug 8, 2017 in Theory of Computation by learner_geek Active (3.1k points) | 88 views

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1 answer

26

TestBook TestSeries
Consider the following statements : i) An ambiguous grammar can not generate DCFL. ii) An unambiguous grammar will always generate deterministic context free language. iii) Any non-empty language admits an ambiguous grammar. iv) All regular grammars are unambiguous. Which of the above is/are TRUE? i) and iv) only ii) and iii) only iii) only ii) and iv) only

asked Jan 29, 2017 in Theory of Computation by vnc Active (2.8k points) | 79 views

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27

Self Doubt
By seeing a grammar I can say it is ambiguous or not. But How can I say it is inherently ambiguous or not.?

asked Jan 22, 2017 in Theory of Computation by Lucky sunda Active (4.4k points) | 132 views

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28

Grammar ambiguity and parsing
$\begin{align*} \text {stmt} &\rightarrow \text{if expr then stmt else stmt} \\ & \;\; \;\; | \text{ if expr then stmt} \\ & \;\; \;\; | \text{ other} \end{align*}$ Which of the following statement/s is ... and the ambiguity cannot be resolved. B. The grammar is unambiguous C. The grammar is ambiguous and the ambiguity can be resolved D. None of these

asked Dec 15, 2016 in Compiler Design by dd Veteran (56.6k points) | 235 views

+6 votes

3 answers

29

Dangling Else Problem and Ambiguity Elimination
For the grammar given below $\textbf{stmt} \to$ $ \textbf{if} $expr$ \textbf{then}$ stmt $\mid $ $\textbf{if}$ expr $ \textbf{then}$ stmt$ \textbf{else}$ stmt $\mid \textbf{other} $ Which of the following ... and the ambiguity cannot be resolved. 3.The grammar is unambiguous. If we try to remove nondeterminism , will ambiguity always be removed?

asked Nov 21, 2016 in Compiler Design by vaishali jhalani Active (4.6k points) | 2k views

+14 votes

1 answer

30

GATE1987-1-xii
A context-free grammar is ambiguous if: The grammar contains useless non-terminals. It produces more than one parse tree for some sentence. Some production has two non terminals side by side on the right-hand side. None of the above.

asked Nov 8, 2016 in Theory of Computation by makhdoom ghaya Boss (29.5k points) | 913 views

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