## What is undecidable language in Turing machine?

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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.

## Is there a language for every Turing machine?

The TM will then either accept the string, reject the string, or loop on the machine. The language of a TM is defined as the set of all the strings it accepts. Not every language is the language of a Turing machine – that’s one of the landmark results of theoretical computer science.

**Are Turing machines undecidable?**

Alan Turing proved in 1936 that a general algorithm running on a Turing machine that solves the halting problem for all possible program-input pairs necessarily cannot exist. Hence, the halting problem is undecidable for Turing machines.

**How do you show an undecidable language?**

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.

### How many undecidable languages are there?

two undecidable languages

We’ve now proven the existence of two undecidable languages (ATM and ATM) and one unrecognizable language (ATM).

### What is decidable and undecidable languages?

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.

**Are undecidable problems unsolvable?**

An undecidable problem is one for which no algorithm can ever be written that will always give a correct true/false decision for every input value. Undecidable problems are a subcategory of unsolvable problems that include only problems that should have a yes/no answer (such as: does my code have a bug?).

**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’.

#### What makes something undecidable?

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.