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From: olcott <polcott333@gmail.com>
Newsgroups: comp.theory,sci.logic
Subject: Re: Termination analyzer defined ---RICHARD IS WRONG !!!
Date: Tue, 14 May 2024 09:18:40 -0500
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On 5/14/2024 4:34 AM, Mikko wrote:
> On 2024-05-13 18:07:37 +0000, Jeff Barnett said:
> 
>> On 5/13/2024 3:06 AM, Mikko wrote:
>>
>>> Anyway, if an analyzer can never tell whether a program terminates
>>> with every possible input then it is not a termination analyzer.
>>
>> I don't think the above is true in the way you meant it. Recall that 
>> the collection of all Turing machines with blank input tapes is the 
>> same set of computations as the collection with arbitrary input tapes. 
>> It's always possible to take any specific machine, T, and initial 
>> tape, I, and produce machine T' with blank initial input tape that is 
>> equivalent: T' initially writes I on its tape (say one character 
>> output per state in sequence) then continues with the set of states 
>> that comprises T.
>>
>> So it is obvious that a termination analyzer (AKA a halt decider) 
>> restricted to blank tape problems will do quite nicely and it is also 
>> quite obvious that no such entity exists.
> 
> You only discuss halting decisions with specific inputs. THerefore you say
> nothing about termination analyzers and don't show any mistake in my 
> comment.
> 

00 int H(ptr x, ptr x)  // ptr is pointer to int function
01 int D(ptr x)
02 {
03   int Halt_Status = H(x, x);
04   if (Halt_Status)
05     HERE: goto HERE;
06   return Halt_Status;
07 }
08
09 int main()
10 {
11   H(D,D);
12 }

In any case you diverged away form the whole point of this thread.
Richard is wrong when he says that there exists an H/D pair such
that D simulated by H ever reaches past its own line 03.

-- 
Copyright 2024 Olcott "Talent hits a target no one else can hit; Genius
hits a target no one else can see." Arthur Schopenhauer