Question

Define decidable and undecidable problems in toc

Answer 1

A problem is said to be decidable if you can always answer it with either "yes" or "no".

For example,

"Did you eat?" "Do you have a pen?" “is your work done?”

You can always answer "yes" or "no" for such questions.

Such problems are what we call decidable or in other words we call them as "solvable". Otherwise the class of problems is said to be "undecidable" or "insolvable".

To be more precise with the subject, a problem is said to be decidable if some Turing machine decides or solves with YES or NO for each instance of the problem.

Otherwise the problem is undecidable.