What languages can Turing machine recognize?
The turing machine accepts all the language even though they are recursively enumerable. Recursive means repeating the same set of rules for any number of times and enumerable means a list of elements.
What is undecidable language in Turing machine?
For an undecidable language, there is no Turing Machine which accepts the language and makes a decision for every input string w (TM can make decision for some input string though). A decision problem P is called “undecidable” if the language L of all yes instances to P is not decidable.
Can a Turing machine recognize multiple languages?
A language is recursively enumerable (generated by Type-0 grammar) if it is accepted by a Turing machine. A TM decides a language if it accepts it and enters into a rejecting state for any input not in the language….Example 1.
| Tape alphabet symbol | Present State ‘q1’ | Present State ‘q2’ |
|---|---|---|
| α | BRq2 | BRq1 |
Which of the following languages are undecidable?
L1 is undecidable. According to Rice’s theorem, emptiness problem of Turing machine is undecidable.
Which language is not accepted by Turing machine?
the diagonalization language
We have seen one language, the diagonalization language, that is not accepted by any Turing machine. This proves the diagonalization language is not recursively enumerable.
How do you know if a language is Turing recognizable?
Recognizable Language A Turing machine M recognizes language L if L = L(M). We say L is Turing-recognizable (or simply recognizable) if there is a TM M such that L = L(M). Decidable Language A Turing machine M decides language L if L = L(M) and M halts on all inputs.
Is the union of two undecidable languages undecidable?
If L is the union of two regular languages, then its complement L is regular. If L is the union of two regular languages, then its complement L is context-free. If L is the union of two decidable languages, then L is decidable. If L is the union of two undecidable languages, then L is undecidable.
What are undecidable problems about Turing machine?
The problems for which we can’t construct an algorithm that can answer the problem correctly in the infinite time are termed as Undecidable Problems in the theory of computation (TOC). A problem is undecidable if there is no Turing machine that will always halt an infinite amount of time to answer as ‘yes’ or ‘no’.
Can a Turing machine accept an infinite language?
Yes, a Turing machine can decide that langauge: it just looks at the first character and accepts or rejects without even needing to look at the rest of the string.
Which of the following languages are undecidable note that M indicates encoding of the Turing machine M?
GATE | GATE CS 2020 | Question 36 Which of the following languages are undecidable? Note that ⟨M⟩ indicates encoding of the Turing machine M. Explanation: L1 = { ⟨M⟩ ∣ L(M)=∅ } is emptiness problem of TM, which is undecidable, by Rice’s theorem since it is a non-trivial problem.
How do you prove Turing machine undecidable?
For a correct proof, need a convincing argument that the TM always eventually accepts or rejects any input. How can you prove a language is undecidable? To prove a language is undecidable, need to show there is no Turing Machine that can decide the language.
What is Turing acceptable?
A language is called Decidable or Recursive if there is a Turing machine which accepts and halts on every input string w. Every decidable language is Turing-Acceptable. A decision problem P is decidable if the language L of all yes instances to P is decidable.