Encyclopedia > Undecidable

  Article Content

Undecidable language

Redirected from Undecidable

In computability theory, a decision problem is undecidable if there is no algorithm that can always give the correct answer.

If there is an algorithm that answers YES when the correct answer is YES, and runs forever when the correct answer is NO, then the problem is partially decidable. A problem can be both undecidable and partially decidable. One example of this is the halting problem.

If there is an algorithm that always answers correctly, both for YES and NO answers, then the problem is decidable, and is not undecidable.

A formal language is said to be undecidable if the decision problem "is a given string in this language" is undecidable.



All Wikipedia text is available under the terms of the GNU Free Documentation License

 
  Search Encyclopedia

Search over one million articles, find something about almost anything!
 
 
  
  Featured Article
BBC News 24

... few viewers. Their response was to promote the channel through their ordinary channels BBC1 and BBC2, using terrestrial signals, and this is seen by some as influential (to ...

 
 
 
This page was created in 26.2 ms