In formal language theory, a context-free language (CFL) is a language generated by some context-free grammar (CFG). The set of regular languages is a subset of the set of context-free languages.
Questions tagged [context-free-language]
183 questions
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Context free grammar for CFL
enter code hereHallo, this is my question
Give context free grammar for CFL
L = {a^nb^mc^n | m, n ∈ N0}
My answer is
S-> ASC| B
A-> aA| a
B-> bB| b
C-> cC| c
Whether my answer or not ? I am not sure about it.
Need some help. thanks in advance
Ejaz Ahamed
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Prove the grammar are Ambiguous
Can anyone please tell me how to prove this grammar are Ambiguous ? thanks in advance.
I cannot find the string which shows the grammar are Ambiguous :(
G2 = { {S}, {a,b}, {S->ab|ba|SS}, S }
Ejaz Ahamed
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Construct a grammar for a language
I have a question regarding this question:
L= empty where the alphabet is {a,b}
how to create a grammar for this ? how can be the production rule ?
thanks in advance
Ejaz Ahamed
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classify as regular, context free, or other
Could someone answer these questions and dumb it down for me please, I am not fully grasping the ideas. I am overall confused at things like "what exactly are terminals?""What does w stand for?"
but as for the real question here they are, please…
user5717696
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Nondeterministic Pushdown Automata different diagrams
In introduction to the theory of computation book, for the language a state diagram is given as :
I know there could be alternative diagrams but I doubt the solution I found might be wrong which is slightly different than the original one:
I…
Nili Miliy
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Is this a context free or context sensitive language?
I am studying Formal Languages and Automata Theory, and I have a question about a problem inside the book that is not answered in it. the question is:
Is this language Context Free, Regular or Context Sensitive?
L={a^i b^j c^k|i<=j or j<=i , j=k}
a_m
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How to generate the FIRST set of this context-free grammar
I've been trying to find the "first set" of this context-free grammar. I've come up with 2 answers but I'm unsure if they're correct. I would be grateful if someone could explain how to generate the first set of this grammar.
Both answers are…
fs2ly
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Eliminating epsilon rules
Hi I have the following CFG
S -> aA | bC | CC
A -> B
B -> S | epsilon
C -> A | S
I have managed to remove the epsilon resulting to:
S -> aA | bC | CC | a | b | C
A -> B
B -> S
C -> A | S
Im in the point of removing unit rules and it resulted in…
Euel Domingo
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Trying to prove that the complement of {a^i b^i c^i} is a context-free
I'm trying to prove that the complement of L= {a^i b^i c^i : i >= 1} is a context free. L complement is: {w is a word over {a,b,c}* : w not in L}.
As we know, context-free languages are closed under union. So, I'm trying to divide my language…
AIM
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Why the following language satisfies the pumping lemma for cfl
L = {a^n b c^n| i is greater than 1 and less than 100 , n is greater than 1}
I think i misunderstood the pumping lemma for cfl.
why cant i pick a word z = a^n c b^n then break it apart to u= a^s v = a^n-s w=epsilon x=b ,y= b^n then pump it with i=0…
gil
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Chomsky Normal Form Conversion Algorithm
Why do we add a new start state S0 -> S when we want to convert a grammar to Chomsky normal form? What goes wrong if we do not do that?
At first I thought it's because of epsilon rules. But we do not remove an epsilon rule from start variable. So,…
A. Mashreghi
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What formalism doesn't belong and which are more powerful/equal
I have this list of formalisms and i need to order them according to their expressive power, also one of them doesn't really belong.
Context-free Grammar(CFG)
Deterministic Finite Automata(DFA)
Deterministic Pushdown Automata(DPDA)
LR(0)…
Conviley
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understanding basics of CFG
Have just started the chapter about CFL in Sipser's book and already fail to understand the basics.
Let this be the grammar of some language:
S -> A0A
A -> 00A | 11A | 10A | 01A | e
I am really confused about this A0A part. Does it mean that the…
Multik
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{a^nb^n} union {a }is deterministic or not
I am confused according to me it should not be deterministic as there will be states for (a,zo/azo) going to q1 and (a,z0/eplison) going to final state. Is this true or not
simranjit singh
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Context free grammars with nesting and inequalities
I've been unable to find any examples of context-free grammars that have nesting and inequalities.
For instance, I am trying to write the CFG for:
{aibjckdl : (i < l) ^ (j < k)}
So, for {aidl : (i < l)}, the CFG would simply be:
S -> aSd | dS | d
It…
James
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