What types of problems are undecidable
Which of the problems are undecidable?
In computability theory, an undecidable problem is a type of computational problem that requires a yes/no answer, but where there cannot possibly be any computer program that always gives the correct answer; that is, any possible program would sometimes give the wrong answer or run forever without giving any answer.
What are undecidable problems in automata?
Undecidable Problems
A problem is undecidable if there is no Turing machine which will always halt in finite amount of time to give answer as ‘yes’ or ‘no’. An undecidable problem has no algorithm to determine the answer for a given input.
What problems are not computable?
(Undecidable simply means non-computable in the context of a decision problem, whose answer (or output) is either “true” or “false”). A non-computable is a problem for which there is no algorithm that can be used to solve it. Most famous example of a non-computablity (or undecidability) is the Halting Problem.
Which of the following problems is are decidable?
Answer
- This is a variation of Turing Machine Halting problem and it is undecidable.
- CFL are not closed under complement so it is undecidable.
- Complement of Regular languages is also regular. …
- Recursvie language are closed under complement,so it is decidable.
Which of the following problems are undecidable Mcq?
Only ambiguity problem for CFGs are undecidable.
Which among the following are undecidable theories?
3. Which among the following are undecidable theories? Explanation: Tarski and Mostowski in 1949, established that the first order theory of natural numbers with addition, multiplication, and equality is an undecidable theory.
Which of the following is are decidable?
Which of the following are decidable? Explanation: (A) Intersection of two regular languages is regular and checking if a regular language is infinite is decidable.
Which of the following are undecidable Mcq?
It is known that P1 is decidable and P2 is undecidable….Online Test.123.Which of the following problems is undecidable?a.Membership problem for CFGsb.Ambiguity problem for CFGsc.Finiteness problem for FSAsd.Equivalence problem for FSAs
Which of the following are undecidable for a given TM?
Discussion Forum
| Que. | Which of the following statements are undecidable? For a given Turing Machine M, |
|---|---|
| b. | does M halt for anly inputs at all? |
| c. | is L(M) regular? Context free? Turing decidable? |
| d. | all of the mentioned |
| Answer:all of the mentioned |
Which of the following is a are undecidable?
Which of the following is/are undecidable? Explanation: First is Emptiness for CFG; whether a CFG is empty or not, this problem is decidable. Second is everything for CFG; whether a CFG will generate all possible strings (completeness of CFG), this problem is undecidable.
Which of the following are undecidable G is a CFG?
Correct Option: D G is a CFG.
Which of the following languages W is undecidable?
L1 is undecidable. According to Rice’s theorem, emptiness problem of Turing machine is undecidable.
Which of the operations are eligible in PDA?
Which of the operations are eligible in PDA? Explanation: Push and pop are the operations we perform to operate a stack. A stack follows the LIFO principle, which states its rule as: Last In First Out.
What is a Turing machine in theory of computation?
A Turing machine is a computational model, like Finite Automata (FA), Pushdown automata (PDA), which works on unrestricted grammar. The Turing machine is the most powerful computation model when compared with FA and PDA. Formally, a Turing machine M can be defined as follows − M = (Q, X, ∑, δ, q0, B, F)
Which of the following pairs of regex are not equivalent Mcq?
Which of the following pair of regular expression are not equivalent? Explanation: (ab)*=(a*b*)*.
Why PDA is more powerful than FA?
A PDA is more powerful than FA. Any language which can be acceptable by FA can also be acceptable by PDA. PDA also accepts a class of language which even cannot be accepted by FA. Thus PDA is much more superior to FA.
Which of the following language Cannot be accepted by PDA?
A DPDA can accept languages like Lwcw that are not regular, but there are CFL (like Lwwr) that cannot be accepted by a DPDA. Theorem: If L is the language accepted by some DPDA P, then L has an unambiguous CFG.
How many types are used to define push down automata Mcq?
Push down automata accepts _________ languages. 8. 9. A push down automaton with only symbol allowed on the stack along with fixed symbol.
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Online Test.
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Online Test.
| 6. | A non deterministic two way, nested stack automaton has n-tuple definition. State the value of n. |
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| c. | 4 |
| d. | 10 |
Is Turing machine powerful than PDA?
2 Answers. If you only consider that ‘Turing machines can always be made to behave like a stack’ you can only conclude that they are at least as powerful as pushdown automata. But in general, yes it is true, Turing machines are more powerful than PDAs.
How PDA are different from finite automata?
Pushdown automata has the additional stack for storing long sequence of alphabets. Finite Automata doesn’t has any space to store input alphabets.
Is PDA part of finite control?
Pushdown Automata is a finite automata with extra memory called stack which helps Pushdown automata to recognize Context Free Languages. A Pushdown Automata (PDA) can be defined as : Q is the set of states. ∑is the set of input symbols.
Which automata is more powerful?
The most general and powerful automata is the Turing machine.