Re: Incorrect requirements --- Computing the mapping from the input to HHH(DD)

Op 09.mei.2025 om 17:48 schreef olcott:

On 5/9/2025 3:47 AM, Fred. Zwarts wrote:

Op 09.mei.2025 om 04:23 schreef Keith Thompson:

Richard Damon <richard@damon-family.org> writes:

On 5/8/25 7:53 PM, olcott wrote:

[...]

void DDD()
{
    HHH(DDD);
    return;
}
We don't need to look at any of my code for me
to totally prove my point. For example when
the above DDD is correctly simulated by HHH
this simulated DDD cannot possibly reach its own
"return" instruction.

>
And thus not correctly simulatd.
>
Sorry, there is no "OS Exemption" to correct simulaiton;.

>
Perhaps I've missed something.  I don't see anything in the above that
implies that HHH does not correctly simulate DDD.  Richard, you've read
far more of olcott's posts than I have, so perhaps you can clarify.
>
If we assume that HHH correctly simulates DDD, then the above code is
equivalent to:
>
     void DDD()
     {
       DDD();
       return;
     }
>
which is a trivial case of infinite recursion.  As far as I can tell,
assuming that DDD() is actually called at some point, neither the
outer execution of DDD nor the nested (simulated) execution of DDD
can reach the return statement.  Infinite recursion might either
cause a stack overflow and a probable program crash, or an unending
loop if the compiler implements tail call optimization.
>
I see no contradiction, just an uninteresting case of infinite
recursion, something that's well understood by anyone with a
reasonable level of programming experience.  (And it has nothing to
do with the halting problem as far as I can tell, though of course
olcott has discussed the halting problem elsewhere.)
>
Richard, what am I missing?
>

>
What you are missing is that the next step of olcott is to say that when he uses the 'exact same HHH, with only some extra code to abort the simulation', it is still an infinite recursion. He does not understand that adding the abort code makes the behaviour fundamentally different.

 When 1 or more statements of DDD are correctly simulated
by HHH this correctly simulated DDD cannot possibly reach
its own "return statement" final halt state.
 

You see? Exactly what I predicted. Now he uses another HHH that does not correctly simulate the whole input, but only makes a start. He will still hold his claim that there is an infinite recursion and may quote a C expert, Keith Thompson, to support his claim. The only way out is that Keith Thompson explicitly explains that his example only holds for the simulator that does not stop after 1 or more statements.