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Results tagged with context-free
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user 94287
Questions about the set of languages (equivalently) described by context-free grammars or accepted by (non-deterministic) pushdown automata.
1
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0
answers
232
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Context-free or not: $a^nww^Ra^n$
Is the following a context-free language?
$$L = \{a^n w w^R a^n \mid n \geq 0, w \in \{a,b\}^*\}$$
I think no because the number of $w$'s is not equal.
Somebody please guide me.
- 251
1
vote
1
answer
68
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Formal languages: What is $2n_c$?
I have got following question:
Determine whether the following language is context free or not:
$$L = \{ w \in \{a,b,c\}^*: n_a (w) = n_b (w) = 2n_c (w)\}. $$
What is the meaning of $2n_c$ in the a …
- 251
1
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2
answers
80
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Difference between $a^{2n} b^n$ and $n_a(w) = 2n_b(w)$
I have encountered two questions related to npda:
Construct an npda for $L_1 = \{a^{2n} b^n \mid n \geq 0\}$ as a language over $\Sigma = \{a,b,c\}$.
Construct an npda for $L_2 = \{w \in \{a, b, c\} …
- 251