Possible Duplicate:Are there any proofs the undecidability of the halting problem that does not depend on self-referencing or diagonalization ? As is stated, can every undecidability proof can be stated in form of diagonalization?Also, can halting problem be reduced to every undecidable problem? (we all know that every undecidable problem can be reduced to halting problem)Thanks.
Can every undecidability proof be converted into diagonalization proof?
halting problem