Re: How to write a self-referencial TM?

On 2025-05-14 17:24:36 +0000, olcott said:

On 5/14/2025 11:43 AM, wij wrote:

On Wed, 2025-05-14 at 09:51 -0500, olcott wrote:

On 5/14/2025 12:13 AM, wij wrote:

Q: Write a turing machine that performs D function (which calls itself):
 void D() {
  D();
}
 Easy?
 

 That is not a TM.

 It is a C program that exists. Therefore, there must be a equivalent TM.
 

To make a TM that references itself the closest
thing is a UTM that simulates its own TM source-code.

 How does a UTM simulate its own TM source-code?

 You run a UTM that has its own source-code on its tape.

A UTM requires a translation to its input language. A source code cannot
be used unless it happens to be written in the UTM's input language.
--
Mikko