On 6/20/2022 1:38 PM, Ben Bacarisse wrote:
> Paul N <
gw7...@aol.com> writes:
>
>> On Friday, June 17, 2022 at 8:39:57 PM UTC+1, olcott wrote:
>>> comp.theory:
>>> [Solution to one instance of the Halting Problem]
>>> On 3/14/2017 9:05 AM, peteolcott wrote:
>>>
>>> Essence of the culmination five years of full time work on the Halting
>>> Problem when I first discovered (see above) that a simulating halt
>>> decider could correctly determine the halt status of the "impossible"
>>> input:
>>
>> Stepping back a bit from the detail of this, may I ask where you
>> intend going with this? Suppose for example that you posted something
>> that did make Flibble, Richard and the others realise that they were
>> mistaken and admit it. Would you regard the admiration of half a dozen
>> people, one calling himself "Mr Flibble", as a worthwhile reward for
>> five years of full-time work?
>
> Five? He first "solved" the halting problem 18 years ago!
>
> BTW, if it was you that gave him the "review" he wanted in
> comp.lang.c++, you were lead stray by his trace. It does not show
> what he claims it shows.
>
> He's now being very clear about the trick he's trying to pull. There's
> nothing "in P" that can stop the apparent infinite recursion, but that's
> just sophistry. H is as much part of the computation as any other and H
> should, stop the recursion when it returns 0 to P. But he gets around
> that by "aborting" (by which I think he means a non-local transfer of
> control) so execution never reaches P's ret instruction. His claim that
> H is a pure function is just bogus.
>
#include <stdint.h>
typedef void (*ptr)();
void P(ptr x)
{
if (H(x, x))
HERE: goto HERE;
return;
}
int main()
{
Output("Input_Halts = ", H(P, P));
}
_P()
[00001352](01) 55 push ebp
[00001353](02) 8bec mov ebp,esp
[00001355](03) 8b4508 mov eax,[ebp+08]
[00001358](01) 50 push eax // push P
[00001359](03) 8b4d08 mov ecx,[ebp+08]
[0000135c](01) 51 push ecx // push P
[0000135d](05) e840feffff call 000011a2 // call H
[00001362](03) 83c408 add esp,+08
[00001365](02) 85c0 test eax,eax
[00001367](02) 7402 jz 0000136b
[00001369](02) ebfe jmp 00001369
[0000136b](01) 5d pop ebp
[0000136c](01) c3 ret
Size in bytes:(0027) [0000136c]
Every sufficiently competent software engineer can easily verify that
the complete and correct x86 emulation of the input to H(P,P) by H would
never reach the "ret" instruction of P.
>> Or do you intend going further, eg
>> getting the results published elsewhere?
>
> If he ever does publish, it will be in one of those predatory journals
> that change fees.