Use this tag in the cases where a parser cannot resolve an ambiguous grammar. For example, when a compiler cannot determine the right choice because an identifier can signify multiple different things.
Questions tagged [ambiguous-grammar]
121 questions
0
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1 answer
Unambigous grammar to ambiguous
I don't know if it is the right site to ask this. But we're studying about ambiguities of grammar. Including left most derivation and right most derivation. My practice problem is this:
E -> E * E | E + E | N
N -> 0N | 1N |
Output: 0110 + 110 *…
Yodism
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1 answer
Parsing Cool Language with antlr, cant print the desired out put
I'm a writing a parser/lexer for COOL ( classroom object-oriented language ). u can see the grammar in the following link: ( LAST PAGE OF THE MANUAL )
http://theory.stanford.edu/~aiken/software/cool/cool-manual.pdf
I am using ANTLR to write this…
Ashkan Kazemi
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1 answer
Ambiguity in Context free Grammar
Question
Show that the context-free grammar "S->SbS|ScS|a" is ambiguous by
giving two parse trees for the string abaca.
I don't get how the string is ambiguous ? I was reading a book on compilers and self learning so i was doing this question in…
user1010101
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1 answer
Find each of the following languages? (grammar)
I want to, for each of the following languages on Τ={a, b, c}, construct the corresponding regular expression and regular grammar:
All strings containing exactly three a’s.
All strings containing at most three b’s.
How can I do this?
0
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1 answer
Show the following grammar is ambiguous
I'm trying to identify a sentence that can produce more than one derivation tree. Also provide two different trees from the sentence
=
= + |
= a | b | c
p.s i have a hard time figuring out the sentences
user3791401
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0
votes
1 answer
Rule not recognized
I've written a grammar which should allow me to define variables and arrays. Everything worked fine until I split up the variables into local and global variables. Now my parser doesn't recognize the arrays anymore (it says it would be a variable…
Raven
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1 answer
context free grammar ambiguous?
For the following context free grammar:
S --> (S) | SS | A
A --> a | A,A | E (E is the empty string)
The formal definition is:
G=(V,T,P,S)
V={A,S}
T={E;a; ( ; ) ; , }
S=S
P:
S --> (S)
S --> SS
S --> A
A -->a
A -->A,A
A --> E (E is…
user2880113
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0
votes
1 answer
LALR grammar ambiguous
I have made a grammar for boolean and arithmetic expressions. I want to handle arithmetic expressions like:
(1+5)+(-3)
I'm done with that work: I can handle all the expressions I want.
My problem is that a boolean expression can be something…
Jorge Silva
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1 answer
How do I make this simple grammar unambiguous?
Here is the ambiguous grammar for a simple DDC compiler in BNF form:
::= |
::= |
::= |
::= 0 | 1 | 2 | 3 | 4 | 5 |…
amorimluc
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1 answer
Failed Predicate Exception
Can anyone give me some examples of Failed Predicate exception in ANTLR.
and some examples that will clearly explain :- input mismatch VS failed predicate VS no viable alt exceptions in ANTLR. thanks in advance.
-1
votes
1 answer
Unambiguous grammar for expressions with let and addition
What is an unambiguous grammar equivalent to to the following ambiguous grammar for a language of expressions with let and addition?
E ⇒ let id = E in E
E ⇒ E + E
E ⇒ num
The ambiguity should be solved so that:
addition is left associative
addition…
Romildo
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-1
votes
1 answer
Compilers: change ambiguous grammar
I have a little problem with this exercise.
Given this grammar:
S -> aX | X
X -> aXb | b | eps
a) shows that it is ambiguous with a string
b) say what language captures the grammar
c) change the grammar and build a descendant parser
Solution by…
Federico
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1 answer
Confused at transferring an ambiguous grammar to an unambiguous one
An ambiguous grammar is given and I am asked to rewrite the grammar to make it unambiguous. In fact, I don't know why the given grammar is ambiguous, let alone rewriting it to an unambiguous one.
The given grammar is S -> SS | a | b , and I have…
Zhao
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-2
votes
3 answers
Can you explicitly use a constructor overload?
If I have 2 constructor overloads
calculations(double vector, double angle);
calculations(double horizontalVector, double verticalVector);
How can I ensure the compiler specifically uses one of the overloads that I choose (as each of them do…
asjhdbashjdbasjhdbhjb
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-2
votes
1 answer
Find a s-grammar (simple grammar)
find a simple grammar (a.k.a s-grammar) for the following language:
L={(ab)2mb :m>=0}
[i did this but it is wrong]
S-> aASBB|b
A-> a
B->b
Fulla
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