What is Decidability explain in brief about any two undecidable problems?
What is Decidability explain in brief about any two undecidable problems?
The problems for which we can’t construct an algorithm that can answer the problem correctly in finite time are termed as Undecidable Problems. These problems may be partially decidable but they will never be decidable.
What is Decidability in Turing machine?
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.
Which of the problems are unsolvable by Turing machine?
One of well known unsolvable problems is the halting problem. It asks the following question: Given an arbitrary Turing machine M over alphabet = { a , b } , and an arbitrary string w over , does M halt when it is given w as an input? It can be shown that the halting problem is not decidable, hence unsolvable.
What is Decidability in theory of automata write down the steps for finding whether two languages are equivalent or not?
Hence, the state entry problem is undecidable. 2. Given two regular languages L1 and L2, is the problem of finding whether a string ‘w’ exists in both L1 and L2, a decidable problem or not. First we make two Turing machines TM1 and TM2 which simulate the DFAs of languages L1 and L2 respectively.
What do you understand by undecidable problem prove that halting problem of Turing machine is undecidable?
The Halting Problem is Undecidable: Proof Since there are no assumptions about the type of inputs we expect, the input D to a program P could itself be a program. Compilers and editors both take programs as inputs.
Why do we study Decidability?
• decidable problems concerning context-free languages But … We need to study this phenomenon for two reasons: First, knowing that a problem is algorithmically unsolvable is useful because then you realize that the problem must be simplified or altered before you can find an algorithmic solution.
How do you prove Decidability?
To show that a language is decidable, we need to create a Turing machine which will halt on any input string from the language’s alphabet. Since M is a dfa, we already have the Turing Machine and just need to show that the dfa halts on every input.
Which are the problems are unsolvable?
Discussion Forum
| Que. | Which of the problems are unsolvable? |
|---|---|
| b. | Boolean Satisfiability problem |
| c. | both a and b |
| d. | None of the mentioned |
| Answer:both a and b |
What is unsolvable problem in TOC?
(definition) Definition: A computational problem that cannot be solved by a Turing machine. The associated function is called an uncomputable function. See also solvable, undecidable problem, intractable, halting problem.
What is membership problem?
In mathematics and theoretical computer science, the semi-membership problem for a set is the problem of deciding which of two possible elements is logically more likely to belong to that set; alternatively, given two elements of which at least one is in the set, to distinguish the member from the non-member.
What is undecidable problem how it can be solved?
There are some problems that a computer can never solve, even the world’s most powerful computer with infinite time: the undecidable problems. An undecidable problem is one that should give a “yes” or “no” answer, but yet no algorithm exists that can answer correctly on all inputs.
What is the difference between Turing decidable and semi-decidable problems?
It is also important to know that these problems are termed as Turing Decidable since a Turing machine always halts on every input, accepting or rejecting it. Semi-Decidable problems are those for which a Turing machine halts on the input accepted by it but it can either halt or loop forever on the input which is rejected by the Turing Machine.
What are the limitations of the Turing machine?
It is worth noting that the Turing machine simulates the random-access machine (RAM), or the general computer. However, Turing machine has limitation; later we will see some problems are not solvable by this model. A language L ( M) is called recognizable if some Turing machine M accepts (recognizes) it.
How does a Turing machine work on a tape?
There is a tape head that can read and write symbols and move around on the tape. One difference from DFA or CFG is that the input for the Turing machine is actually on the tape: initially the tape contains only the input string and is blank everywhere else.
What is the difference between DFA and Turing machine?
One difference from DFA or CFG is that the input for the Turing machine is actually on the tape: initially the tape contains only the input string and is blank everywhere else. When the machine starts, it will move around its states, tape head, and write content on the tape according to the transition function.
