Give an example of undecidable problem? algorithm that takes as input an instance of the problem and determines whether the answer to that instance is “yes” or “no”. (eg) of undecidable problems are (1)Halting problem of the TM.

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## When we say a problem is decidable give an example of undecidable problem?

Give an example of undecidable problem? algorithm that takes as input an instance of the problem and determines whether the answer to that instance is “yes” or “no”. (eg) of undecidable problems are (1)Halting problem of the TM.

**What is undecidable problem write one example how can it be solved?**

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’. The examples of undecidable problems are explained below. Here, CFG refers to Context Free Grammar.

**How do you tell if a language is decidable or undecidable?**

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.

### How do you show a problem is decidable?

By definition, a language is decidable if there exists a Turing machine that accepts it, that is, halts on all inputs, and answers “Yes” on words in the language, “No” on words not in the language. Therefore one way of showing that a language is decidable is by describing a Turing machine that accepts it.

**What is undecidable problem in algorithm?**

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.

**How is Reducibility is used to show problems as decidable or undecidable briefly explain?**

Reducibility involves two problems A and B. When A is reducible to B solving A can not be “harder” than solving B. If A is reducible to B and B is decidable, then A is also decidable. If A is undecidable and reducible to B, then B is undecidable.

## How do you know if a language is decidable or undecidable?

**What is an undecidable Turing machine?**

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. Examples.

**What makes a problem undecidable?**

### What is an example of an intractable problem?

One example of an intractable problem, you have to travel from the starting city to all cities on the map and back to the starting city, for the lowest cost.

**How do you show a Turing machine is 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. This is hard: requires reasoning about all possible TMs.

**Why is the halting problem 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.

## What is decidable problem in computer science?

(definition) Definition: A decision problem that can be solved by an algorithm that halts on all inputs in a finite number of steps. The associated language is called a decidable language. Also known as totally decidable problem, algorithmically solvable, recursively solvable.

**How do you show that a Turing machine is decidable?**

Prove that the language it recognizes is equal to the given language and that the algorithm halts on all inputs. To prove that a given language is Turing-recognizable: Construct an algorithm that accepts exactly those strings that are in the language. It must either reject or loop on any string not in the language.

**What is decidable and undecidable languages in automata?**

A decision problem P is undecidable if the language L of all yes instances to P is not decidable. An undecidable language may be partially decidable but not decidable. Suppose, if a language is not even partially decidable, then there is no Turing machine that exists for the respective language.