Path: news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail
From: "Fred. Zwarts" <F.Zwarts@HetNet.nl>
Newsgroups: comp.theory
Subject: Re: Turing computable functions
Date: Thu, 27 Mar 2025 20:52:32 +0100
Organization: A noiseless patient Spider
Lines: 41
Message-ID: <vs4aa0$101mm$1@dont-email.me>
References: <vruvsn$3tamc$3@dont-email.me> <vs0b8d$19qb8$1@dont-email.me>
 <vs19qe$2346o$2@dont-email.me> <vs39ht$1ogp$1@dont-email.me>
 <vs42l4$mmcb$1@dont-email.me>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Injection-Date: Thu, 27 Mar 2025 20:52:32 +0100 (CET)
Injection-Info: dont-email.me; posting-host="0605c1ac39b5ca87e1425273cb77baa2";
	logging-data="1050326"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX192CCmnAZsVOBk2ABye53Je"
User-Agent: Mozilla Thunderbird
Cancel-Lock: sha1:Kn98uc6pNIq/iybcDTLEhfGXNR4=
Content-Language: nl, en-GB
In-Reply-To: <vs42l4$mmcb$1@dont-email.me>

Op 27.mrt.2025 om 18:41 schreef olcott:
> On 3/27/2025 5:33 AM, Fred. Zwarts wrote:
>> Op 26.mrt.2025 om 17:25 schreef olcott:
>>> On 3/26/2025 2:44 AM, Mikko wrote:
>>>> On 2025-03-25 19:24:07 +0000, olcott said:
>>>>
>>>>> Cannot possibly derive any outputs not computed from
>>>>> their inputs.
>>>>>
>>>>> A Turing machine halt decider cannot possibly report
>>>>> on the behavior of any directly executing process.
>>>>
>>>> It can if that report is a computable function of their inputs.
>>>> For example, whether the direct execution of another Turing machine
>>>> is longer than 2 steps is Turing computable.
>>>>
>>>
>>> When an input to a simulating termination analyzer
>>> defines a pathological relationship to its simulating
>>> termination analyzer this changes the behavior of this
>>> input relative to its direct execution.
> 
>> If an analyser has a pathological relation with this input, it is 
>> wrong to choose this analyser for this input. In particular when there 
>> are analysers that do not have this relationship with this input.
> 
> It is the input that specifies the pathological relationship.
> This means that you are saying that the analyzer should reject
> this input.


Yes, reject because it cannot analyse correctly.
It is not very interesting to know whether an analyser reports that it 
is unable to analyse the problem correctly.
It is interesting to know:
'Is there an algorithm that can determine for all possible inputs 
whether the input specifies a program that (according to the semantics 
of the machine language) halts when directly executed?'
This question seems undecidable for Olcott.