Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail
From: "Fred. Zwarts" <F.Zwarts@HetNet.nl>
Newsgroups: comp.theory
Subject: Re: Simulation vs. Execution in the Halting Problem
Date: Fri, 6 Jun 2025 10:36:05 +0200
Organization: A noiseless patient Spider
Lines: 139
Message-ID: <101u99l$251rf$4@dont-email.me>
References: <yU0_P.1529838$4AM6.776697@fx17.ams4>
 <101a7uv$3vfam$5@dont-email.me> <101br7m$db03$1@dont-email.me>
 <101cjk7$hfof$7@dont-email.me> <101hdjt$21ui2$1@dont-email.me>
 <101iheg$2h3fr$1@dont-email.me>
 <1e5e5837ae9e60daa16e5fef3693ff424c1049d2@i2pn2.org>
 <101j60c$2urhr$3@dont-email.me> <101jiah$33qt3$1@dont-email.me>
 <101khgk$3bfvj$7@dont-email.me> <101m9fs$3sq20$1@dont-email.me>
 <101nlof$7qau$9@dont-email.me> <101osfh$mj67$1@dont-email.me>
 <101pqoc$ta6v$6@dont-email.me> <101rgde$1d34j$3@dont-email.me>
 <101sehk$1kh2e$3@dont-email.me>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
Injection-Date: Fri, 06 Jun 2025 10:36:06 +0200 (CEST)
Injection-Info: dont-email.me; posting-host="e0264a7f49952eafc22259eeb7677921";
	logging-data="2262895"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX19hlImrpQbacpNnyAQHqf8x"
User-Agent: Mozilla Thunderbird
Cancel-Lock: sha1:ZoQi5MWW/66QeRj64yZGdnlknKQ=
In-Reply-To: <101sehk$1kh2e$3@dont-email.me>
Content-Language: nl, en-GB
Bytes: 7521

Op 05.jun.2025 om 17:53 schreef olcott:
> On 6/5/2025 2:19 AM, Fred. Zwarts wrote:
>> Op 04.jun.2025 om 18:03 schreef olcott:
>>> On 6/4/2025 2:26 AM, Mikko wrote:
>>>> On 2025-06-03 20:25:51 +0000, olcott said:
>>>>
>>>>> On 6/3/2025 2:50 AM, Mikko wrote:
>>>>>> On 2025-06-02 15:55:00 +0000, olcott said:
>>>>>>
>>>>>>> On 6/2/2025 2:02 AM, Mikko wrote:
>>>>>>>> On 2025-06-02 03:32:28 +0000, olcott said:
>>>>>>>>
>>>>>>>>> On 6/1/2025 8:19 PM, Richard Damon wrote:
>>>>>>>>>> On 6/1/25 5:41 PM, olcott wrote:
>>>>>>>>>>> On 6/1/2025 6:30 AM, Mikko wrote:
>>>>>>>>>>>> On 2025-05-30 15:41:59 +0000, olcott said:
>>>>>>>>>>>>
>>>>>>>>>>>>> On 5/30/2025 3:45 AM, Mikko wrote:
>>>>>>>>>>>>>> On 2025-05-29 18:10:39 +0000, olcott said:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> On 5/29/2025 12:34 PM, Mr Flibble wrote:
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> 🧠 Simulation vs. Execution in the Halting Problem
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> In the classical framework of computation theory (Turing 
>>>>>>>>>>>>>>>> machines),
>>>>>>>>>>>>>>>> simulation is not equivalent to execution, though they 
>>>>>>>>>>>>>>>> can approximate one
>>>>>>>>>>>>>>>> another.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> To the best of my knowledge a simulated input
>>>>>>>>>>>>>>> always has the exact same behavior as the directly
>>>>>>>>>>>>>>> executed input unless this simulated input calls
>>>>>>>>>>>>>>> its own simulator.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> The simulation of the behaviour should be equivalent to 
>>>>>>>>>>>>>> the real
>>>>>>>>>>>>>> behaviour.
>>>>>>>>>>>>>
>>>>>>>>>>>>> That is the same as saying a function with infinite
>>>>>>>>>>>>> recursion must have the same behavior as a function
>>>>>>>>>>>>> without infinite recursion.
>>>>>>>>>>>>
>>>>>>>>>>>> A function does not have a behaviour. A function has a value 
>>>>>>>>>>>> for
>>>>>>>>>>>> every argument in its domain.
>>>>>>>>>>>>
>>>>>>>>>>>> A function is not recursive. A definition of a function can be
>>>>>>>>>>>> recursive. There may be another way to define the same function
>>>>>>>>>>>> without recursion.
>>>>>>>>>>>>
>>>>>>>>>>>> A definition of a function may use infinite recursion if it 
>>>>>>>>>>>> is also
>>>>>>>>>>>> defined how that infinite recursion defines a value.
>>>>>>>>>>>>
>>>>>>>>>>>> Anyway, from the meaning of "simulation" follows that a 
>>>>>>>>>>>> simulation
>>>>>>>>>>>> of a behaviour is (at least in some sense) similar to the real
>>>>>>>>>>>> behaviour. Otherwise no simulation has happened.
>>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> void DDD()
>>>>>>>>>>> {
>>>>>>>>>>>    HHH(DDD);
>>>>>>>>>>>    return;
>>>>>>>>>>> }
>>>>>>>>>>>
>>>>>>>>>>> The *input* to simulating termination analyzer HHH(DDD)
>>>>>>>>>>> specifies recursive simulation that can never reach its
>>>>>>>>>>> *simulated "return" instruction final halt state*
>>>>>>>>>>>
>>>>>>>>>>> *Every rebuttal to this changes the words*
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> No it doesn't, as HHH is defined to abort and simulation after 
>>>>>>>>>> finite time, and thus only does finite simulation.
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> See right there you changed the words.
>>>>>>>>> I said nothing about finite or infinite simulation.
>>>>>>>>> You said that I am wrong about something that I didn't even say.
>>>>>>>>
>>>>>>>> Again you are trying a sraw man deception. RIchard Damon did not 
>>>>>>>> change
>>>>>>>> your words, he only wrote his own. He did not claim that you 
>>>>>>>> said anything
>>>>>>>> about "finite" or "infinite" but that you should understand the 
>>>>>>>> difference.
>>>>>>>
>>>>>>> Unlike most people here I do understand that not
>>>>>>> possibly reaching a final halt state *is* non-halting behavior.
>>>>>>
>>>>>> You don't understand it correctly. Whether a computation is 
>>>>>> halting is a
>>>>>> feature of the computation, not a particular exectuion of that 
>>>>>> coputation.
>>>>>> A halting computation is a halting computation even if its 
>>>>>> execution is
>>>>>> discontinued before reaching the final halt state.
>>>>>
>>>>> int main()
>>>>> {
>>>>>    DDD(); // Do you understand that the HHH(DDD) that this DDD
>>>>> }        // calls is only accountable for the behavior of its
>>>>>           // input, and thus NOT accountable for the behavior
>>>>>           // of its caller?
>>>>
>>>> I don't set any requirements on HHH. I just note that if HHH does not
>>>> return a value that means "halts" it is not a halt decider and not
>>>> even a partial halt decider, because the direct execution of DDD has
>>>> been shown to halt.
>>>>
>>>
>>> If HHH(DDD) is supposed to report on the behavior
>>> of the direct execution of DDD() then that entails
>>> that HHH must report on the behavior of its caller.
>>> This is not allowed even if it was possible.
>>>
>>
>> The definition of a correct report is to report about the input. Not 
>> about a hypothetical input.
> 
> DDD simulated by HHH cannot possibly reach its "return"
> instruction final halt state. DDD simulated by HHH derives
> that actual behavior that the input to HHH(DDD) actually
> specifies.
> 
Counterfactual. The input specifies a DDD that calls a HHH that includes 
the code to abort and halt. That is the actual behaviour that is specified.
But HHH does not see that, because its programmer is dreaming of a HHH 
that does not abort and uses that dream as a basis to abort the 
simulation before it can see the whole specification of the actual 
behaviour. It uses the behaviour of a dreamed (hypothetical) HHH, 
instead of the actual behaviour. That HHH fails to see the whole 
specification, does not change the fact that the input specifies an 
actual behaviour of a halting program.
Sum(2,3) is supposed to compute the sum of 2 and 3. It is incorrect to 
process only the 2, only because due to a programming error it cannot 
reach the 3.