In: Computer Science
Prove whether the set of all proofs within any formal system is decidable, recognizable, or unrecognizable
A Turing machine M is said to recognize a language L if L =
L(M).
A Turing machine M is said to decide a language L if L = L(M)
and M halts on every input.
L is said to be Turing-recognizable (Recursively Enumerable
(R.E.)
or simply recognizable) if there exists a TM M which recognizes
L.
L is said to be Turing-decidable (Recursive or simply decidable)
if
there exists a TM M which decides L.
But not all languages are decidable! We will show:
Atm = {<M,w >|M is a TM and M accepts w } is
undecidable.
However Atm is Turing-recognizable!
the answer has been provided below: