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Results tagged with undecidability
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user 71238
Questions about problems which cannot be solved by any Turing machine.
0
votes
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Is the decision problem, for a Turing Machine are there any input strings rejected decidable?
Let us start by properly defining your language as say
$$L = \{\langle M \rangle \mid M \text{ rejects some input } x \in \Sigma^\ast\}$$
where $\langle \cdot \rangle$ denotes some suitable encoding o …
- 1,536
4
votes
Turing machine that checks whether a given string is an output of a given machine and input
No, in fact any non-trivial semantic property of Turing machines is undecidable. This result is Rice's theorem.
- 1,536