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Questions related to formal languages, grammars, and automata theory
5
votes
1
answer
143
views
To what factor can I compress information from binary to Quinary
I am trying to think if we can have an injective mapping $\mathcal{f}$, say something like $\Sigma_{bool}= \{0,1\}^* $ to $\Sigma_{5} = \{0,1,2,3,4\}^* $ such that $|x| \leq 2.|\mathcal{f}(x)|$
The m …
1
vote
How do I prove that Context Free languages have more memory than FSM
There's a small mistake in your question.
The FSM (DFA or NFA) are machines that accept regular languages.
the CFL is also a language.
They are accepted by a machine called PDA (PushDown Automata …
0
votes
Prove or disprove whether L is regular
@Shaull's solution is perfect..
here's a slightly different version of it...
try to see, that
$L$ = $L_1 \cup L_2$
where
$L_1 = \{ w \in \{0,1\}^* \mid |w|_0 \gt |w|_1 + 2\}$
$L_2 = \{ w \in …
1
vote
Class of a Language
For a language that is regular but not CF or CS,
construct a DFA/NFA that accepts it
convert it to a regular expression
show that it can be represented as an union, intersection or concatenation of …
0
votes
2
answers
412
views
Equivalence of Context-Free-Grammar and Context-Free-Grammar in CNF
Given any Context-Free-Grammar, $G$, and another in Chomsky Normal Form, $G_c$, how can we check if both $G$ and $G_c$ generate the same language?
One of the trivial ways I know of is to convert $G …
5
votes
Decide if L is regular or not and argue it. Trying to use Pumping Lemma
(a): Recall that regular languages are closed under complement, i.e if $L$ is regular, so is $L'$. ($F_{L'} = Q_L- F_L$)
Assume that $L$ is regular.
This follows: if $L = \{x \in \{0,1\}^* \mid |x|_0 …
0
votes
What does the language {a, b, c}* exactly mean? How will the automaton for this look like?
It means this Language can 'generate' any string using the alphabets $a, b, c$, including the empty string $\epsilon$
There is no bound on the length of the string generated.
Here's a NFA that acce …
3
votes
Accepted
Regular Expression as basis for creating this grammar
$A \rightarrow ba \mid A \mid B \mid cA$
under this $bababaccc$ is also legal
You could try something like this...
$S \rightarrow cS|cA$
$A \rightarrow baA|B$
$B \rightarrow bb$
1
vote
Accepted
Can a Turing Machine decide only non-regular languages?
@Karolis Juodele already gave the answer, and your answer is also correct.
Another thing to keep in mind is although infinite languages can be undecidable, some of them are regular.. ex. $\{0\}^* \su …