context-free-grammar Questions
3
Solved
Consider the following extension to context-free grammars that permits rules to have in the left-hand side, one (or more) terminal on the right side of the non-terminal. That is, rules of the form:...
Bespread asked 22/8, 2012 at 11:20
2
Solved
Can a LR(1) parser parse a grammar of this type?
S -> SA | A
A -> aSb | ab
I'm trying to write a Java program that implements this type of parser, but I only get the right results on a gra...
Bales asked 30/1, 2014 at 16:25
1
Solved
I'd like to define an unordered set of values using an Extended Backus-Naur Form (EBNF) context free grammar. It's easy to define an unordered list of values in EBNF, for example:
value = 'A' | 'B...
Lotus asked 4/6, 2014 at 6:3
2
Solved
I've seen this algorithm one should be able to use to remove all left recursion.
Yet I'm running into problems with this particular grammar:
A -> Cd
B -> Ce
C -> A | B | f
Whatever I tr...
Simferopol asked 14/4, 2013 at 14:2
1
Solved
Can anyone explain to me how FIRST and FOLLOW should be used in LL(1) grammar? I understand that they are used for syntax table construction, but I don't understand how.
Selfsatisfaction asked 1/12, 2013 at 20:58
1
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Making artificial LR(k) grammars for k > 1 is easy:
Input: A1 B x
Input: A2 B y (introduce reduce-reduce conflict for terminal a)
A1 : a
A2 : a
B : b b b ... b (terminal b occurs k-1 times)
Howe...
Discriminate asked 26/11, 2013 at 2:18
1
Does anyone know of a program that uses a GA to perform grammar induction/inference, I've read tonnes of research papers and articles on this stuff like Lankhorst and De Pauw but I can't find any i...
Prosy asked 20/8, 2011 at 10:2
5
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Does the standard specify the official C++ grammar?
I searched, but did not find it anywhere.
Also, I wish to read a bit about C++ grammar in detail, like which category of grammars it falls in, ...
Insist asked 17/5, 2010 at 14:21
1
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How can a formal context free grammar be generated for the following language:
{ai bjck | i != j or j != k}
I have following productions but can't understand it:
S->AX | YC unequal b’s c...
Wenzel asked 20/10, 2013 at 5:32
1
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What algorithm do you use to enumerate the strings generated by a context-free grammar?
It seems doable when there is no recursion, but I can't figure out how to do it in the general case, which m...
Celestyna asked 30/6, 2013 at 6:8
1
On the web, there is a lot of examples showing how to construct parsing tables for a context-free grammar from first/follow sets for LL(1) parser.
But I haven't found anything useful related to k>...
Wieren asked 25/1, 2012 at 10:17
1
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I was trying to implement a LL(1) top-down parser for a calculator language. It only allows us to sum, subtract, divide and multiply numbers. No parentheses.
S -> A
A -> B + A
| B - A
| B...
Marital asked 6/5, 2013 at 19:12
1
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I'm trying to get my head around context free grammars and I think I'm close. What is baffling me is this one question (I'm doing practise questions as I have an exam in a month's time):
I've come...
Patricio asked 13/4, 2013 at 15:5
2
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I've been reading: "Tips for creating Context free grammar" post for learning purposes and I nearly understand the concept, but I don't quite understand the following.
If we have:
L = {am bn |...
Catch asked 13/4, 2013 at 2:12
1
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How can someone validate if a string is part of a context free Grammar? Not just virtually, but build an algorithm for it?
Given a context free grammar with rules such as
V-> v1v2
v1->1 | 1v1
v...
Morehouse asked 23/3, 2013 at 23:52
1
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I just took my midterm but couldn't answer this question.
Can someone please give a couple of examples of the language and construct a grammar for the language or
at least show me how i wi...
Judgemade asked 21/3, 2013 at 22:20
1
I'm trying to prove the following:
If G is a Context Free Grammar in the Chomsky Normal Form, then for any string w belongs L(G) of length n ≥ 1, it requires exactly 2n-1 steps to make any de...
Orebro asked 12/7, 2012 at 16:7
1
We are learning about ambiguity in class, and the following grammar was given as an example of an ambiguous grammar. I just am not seeing how it is ambiguous. Is there a set pattern or method peopl...
Chanson asked 2/3, 2013 at 15:25
1
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I have the following grammar:
S → a S b S | b S a S | ε
Since I'm trying to write a small compiler for it, I'd like to make it LL(1). I see that there seems to be a FIRST/FOLLOW conflict here, an...
Stake asked 1/3, 2013 at 15:52
3
I'm not really very clear on the concept of ambiguity in context free grammars. If anybody could help me out and explain the concept or provide a good resource I'd greatly appreciate it.
Bluebeard asked 17/5, 2011 at 18:30
2
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Basically, I'm trying to syntax highlight the following piece of coffeescript code the way I want it. Explanation of the syntax of coffeescript functions can be found here.
nameHere = (tstamp, moo...
Gothicize asked 3/2, 2013 at 0:36
2
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I'm trying to add 2 things to my grammar:
Unary minus sign, i.e. '-', and
Parentheses
Here's my grammar so far:
<comp> ::= <expr> | <comp> <op0> <expr>
<expr&g...
Bondswoman asked 28/1, 2013 at 2:45
2
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I used to think C++ was the "weird" one with all the ambiguities with < and >, but after trying to implement a parser I think I found an example which breaks just about every language that us...
Renayrenckens asked 19/1, 2013 at 8:29
3
Solved
Given:
I have no idea what the accepted language is.
From looking at it you can get several end results:
1.) bb
2.) ab(a,b)
3.) bbab(a, b)
4.) bbaaa
Wexford asked 26/9, 2011 at 4:38
1
I am having difficulties understanding the principle of lookahead in LR(1) - items. How do I compute the lookahead sets?
Say for an example that I have the following grammar:
S -> AB
A -> a...
Haemophiliac asked 19/11, 2012 at 18:10
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