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Results tagged with undecidability
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user 121549
Questions about problems which cannot be solved by any Turing machine.
0
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Is the languague L={<M>, M accepts a finite amount of words} decdidable?
Is $L=\{<M> | L(M) \ is \ finite\} $ decidable ? M is a TM.
I think its relative simple to proof with the theorem of rice. But I am interested in a solution which does not use the Rice theorem.
This m …
- 147
-1
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1
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Is the Languague which contains all TMs which write the blank symbol at firs by the given in...
Consider the problem of determining whether a Turing machine M on an input w writes the blank symbol at first. Is this decidable ?
- 147
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Is every subset of a decidable set, also decidable?
Its not true.
Proof :
Let $A=\Sigma^*$,we know that $A$ is decidable. Now lets take a look at
$$ \Sigma^*\cap A_{TM}=A_{TM}$$ Since $\Sigma^*$ is the Set which contains all languagues it also contain …
- 147
1
vote
1
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542
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How to prove the language of all Turing Machines that accept an undecidable language is unde...
I want to prove that $L=\{\langle M \rangle |L(M)\text{ is undecidable}\}$ is undecidable
I am not sure about this. This is my try :
Suppose L is decidable. Let $E$ be the decider from $L$. Let $A$ be …
- 147