Path: ...!feeds.phibee-telecom.net!weretis.net!feeder8.news.weretis.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: "Fred. Zwarts" Newsgroups: comp.theory,sci.logic Subject: Re: DD correctly simulated by HH cannot possible halt --- Try to prove otherwise --- x86 DD Date: Mon, 3 Jun 2024 10:10:21 +0200 Organization: A noiseless patient Spider Lines: 95 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Mon, 03 Jun 2024 10:10:22 +0200 (CEST) Injection-Info: dont-email.me; posting-host="4aa76005a7c4778429e99a66774e7ab2"; logging-data="4009662"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+B2N4so9liWKhJM2ulrHjO" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:FUGRgO0Kuz9N/oj9wcDGXKJ/e+k= In-Reply-To: Content-Language: en-GB Bytes: 5718 Op 03.jun.2024 om 05:20 schreef olcott: > On 6/2/2024 10:13 PM, Richard Damon wrote: >> On 6/2/24 10:54 PM, olcott wrote: >>> IT HAS ALWAYS BEEN ABOUT THE BEHAVIOR THAT THE INPUT SPECIFIES. >>> That you did get confused by the Linz text proves that you do >>> get confused. Previously it looked just like willful deception. >> >> Which is, for a Halt Decider, exactly and only the behavior of the >> Turing Machine the input describes. >> >> PERIOD. >> >> Anything else is just a LIE. >> >>> >>>> You don't seem to understand that you can't just "redefine" the >>>> system to meet your desires. >>>> >>> >>> Deciders compute the mapping FROM THEIR INPUTS. >>> DD correctly simulated by HH specifies NON-HALTING. >> >> No, Running DD(DD) and seeing that it will never, after an unbounded >> number of steps, indicate it is non-halting. >> >> DEFINITION. >> >>> >>> Deciders compute the mapping FROM THEIR INPUTS. >>> DD correctly simulated by HH specifies NON-HALTING. >> >> Right, and the input is a representation of a Turing Machine and its >> input, whose behavior the decider is to decide on. >> >>> >>> Deciders compute the mapping FROM THEIR INPUTS. >>> DD correctly simulated by HH specifies NON-HALTING. >>> >> >> And that is the machine the input describes. >> >> ANYTHING ELSE IS JUST A LIE. >> >>> You can't get away with implicitly saying that you >>> just don't "believe in" UTMs. >> >> I do, and a UTM is DEFINED as a machine that exactly reproduces the >> behavior of the machine described by its input. >> > > *If that was true then you prove that this statement is false* > *We can see that the following DD cannot possibly halt when* > *correctly simulated by every HH that can possibly exist* > > typedef int (*ptr)();  // ptr is pointer to int function in C > 00       int HH(ptr p, ptr i); > 01       int DD(ptr p) > 02       { > 03         int Halt_Status = HH(p, p); > 04         if (Halt_Status) > 05           HERE: goto HERE; > 06         return Halt_Status; > 07       } > > _DD() > [00001c22] 55         push ebp > [00001c23] 8bec       mov ebp,esp > [00001c25] 51         push ecx > [00001c26] 8b4508     mov eax,[ebp+08] > [00001c29] 50         push eax        ; push DD 1c22 > [00001c2a] 8b4d08     mov ecx,[ebp+08] > [00001c2d] 51         push ecx        ; push DD 1c22 > [00001c2e] e80ff7ffff call 00001342   ; call HH > [00001c33] 83c408     add esp,+08 > [00001c36] 8945fc     mov [ebp-04],eax > [00001c39] 837dfc00   cmp dword [ebp-04],+00 > [00001c3d] 7402       jz 00001c41 > [00001c3f] ebfe       jmp 00001c3f > [00001c41] 8b45fc     mov eax,[ebp-04] > [00001c44] 8be5       mov esp,ebp > [00001c46] 5d         pop ebp > [00001c47] c3         ret > Size in bytes:(0038) [00001c47] > It is clear (both from the C code as from the compiled code) that at the moment that the outer simulator reaches the place where DD calls HH then HH finds *itself* in a 'repeated state'. At that same moment DD is *not* (yet) in a repeated state. (DD may get in a repeated state if the called HH would start a new simulation.) So, the only conclusion is that it is HH that displays repetition. And because of that DD will repeat as well. By using simulation, a new halting problem is introduced, that has nothing to do with the pathological part of DD n lines 04, 05 and 06. This pathological part is not even processed by the simulation.