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Results tagged with undecidability
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user 103352
Questions about problems which cannot be solved by any Turing machine.
1
vote
1
answer
130
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Is $L = \{ \langle \langle \ M\ \rangle \rangle \ | \ M \ \text{does not accept}\ 010 \} $ T...
I'm working on the following problem:
Is the following language Turing recognizable (recursively enumerable)
?
$$L = \{ \langle \langle \ M\ \rangle \rangle \ | \ M \ \text{does not
> acce …
- 243
1
vote
1
answer
93
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Is $ L = \{ a^n\ |\ a^n \not\in L_n \} $ Turing recognizable (recursively enumerable)?
Say $ \Sigma = \{a\} $, $M_1, M_2, ... $ is an enumeration of all TMs that recognize languages over $\Sigma$ and $L_1, L_2, ... $ are respectively the languages that are recognized by those TMs. We …
- 243
2
votes
1
answer
2k
views
Is $L(G) \subseteq L(R)$ decidable?
Is the following problem decidable?
Given a context-free grammar $G$ and a regular expression $R$, is $L(G) \subseteq L(R)$?
It is given that the following problem is undecidable
Given a co …
- 243