Path: ...!news.nobody.at!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: D correctly simulated by H proved for THREE YEARS --- rewritten Date: Sun, 16 Jun 2024 21:08:35 +0200 Organization: A noiseless patient Spider Lines: 78 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Sun, 16 Jun 2024 21:08:37 +0200 (CEST) Injection-Info: dont-email.me; posting-host="2ca83788b9852bfe87481549f1ce4e04"; logging-data="208059"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX18Y1icxu8euJpMLC2nct7na" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:sOp8lTHhrBVKH9bUEETKdLEX8p0= Content-Language: en-GB In-Reply-To: Bytes: 4769 Op 16.jun.2024 om 14:37 schreef olcott: > On 6/16/2024 1:21 AM, Fred. Zwarts wrote: >> Op 15.jun.2024 om 17:23 schreef olcott: >>> On 6/15/2024 10:12 AM, Fred. Zwarts wrote: >>>> Op 15.jun.2024 om 16:48 schreef olcott: >>>>> On 6/15/2024 9:37 AM, Fred. Zwarts wrote: >>>>>> >>>>>> Is this the new definition of "pathological"? >>>>> >>>>> *It is the same thing that I have been saying all along* >>>>> >>>>> 00   typedef void (*ptr)(); // pointer to void function >>>>> 01 >>>>> 02   int HH(ptr P, ptr I); >>>>> 03 >>>>> 04   void DDD(int (*x)()) >>>>> 05   { >>>>> 06     HH(x, x); >>>>> 07     return; >>>>> 08   } >>>>> 09 >>>>> 10   int main() >>>>> 11   { >>>>> 12     HH(DDD,DDD); >>>>> 13   } >>>>> >>>>> Line 12 main() >>>>>    invokes HH(DDD,DDD); that simulates DDD() >>>>> >>>>> *REPEAT UNTIL outer HH aborts* >>>>>    Line 06 simulated DDD() >>>>>    invokes simulated HH(DDD,DDD); that simulates DDD() >>>>> >>>>> DDD correctly simulated by HH never reaches its own "return" >>>>> instruction and halts. >>>> >>>> So, you agree that you are changing definitions. >>> >>> Not at all. The original definition still applies when it >>> is made more generic. >>> >>> 01       int D(ptr p) >>> 02       { >>> 03         int Halt_Status = H(p, p); >>> 04         if (Halt_Status) >>> 05           HERE: goto HERE; >>> 06         return Halt_Status; >>> 07       } >>> >>> D correctly simulated by H has isomorphic behavior to DDD >>> correctly simulated by HH, both get stuck in recursive >>> simulation. >>> >> >> When asked what is a pathological program olcott replied: >> Op 14.jun.2024 om 21:18 schreef olcott: >>> For any program H that might determine whether programs halt, a >>> "pathological" program D, called with some input, can pass its own >>> source and its input to H and then specifically do the opposite of what >>> H predicts D will do. No H can exist that handles this case. >> >> >> No he defines a "pathological" program as a program that calls H. >> All words about doing the opposite of what H predicts, have disappeared. >> Everyone sees the difference, but he is stuck is rebuttal mode and >> denies the change of definition. >> > > The code that "does the opposite" was never reachable by > a simulating halt decider thus does not change the problem > for a simulating halt decider when this code is removed. So, there was never a relation with the Linz proof, where the part that does the opposite of what H predicts plays the essential role. What remains is the fact that H is unable to simulate itself up to its final state, which is called a "pathological" property of H.