Path: ...!feed.opticnetworks.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Mikko Newsgroups: comp.theory Subject: Re: H(D,D) cannot even be asked about the behavior of D(D) Date: Tue, 18 Jun 2024 10:44:57 +0300 Organization: - Lines: 84 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Tue, 18 Jun 2024 09:44:58 +0200 (CEST) Injection-Info: dont-email.me; posting-host="096eed04dec486be774c007ab37ba2e2"; logging-data="1321635"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX18pmAjnUXwLj30ZhnKsQlPi" User-Agent: Unison/2.2 Cancel-Lock: sha1:Pbzla56ITP312aJXZ2t4dKF0n80= Bytes: 5417 On 2024-06-17 12:51:15 +0000, olcott said: > On 6/17/2024 2:10 AM, Mikko wrote: >> On 2024-06-16 12:59:02 +0000, olcott said: >> >>> On 6/16/2024 4:15 AM, Mikko wrote: >>>> On 2024-06-15 13:24:45 +0000, olcott said: >>>> >>>>> On 6/15/2024 7:33 AM, Mikko wrote: >>>>>> On 2024-06-15 11:34:39 +0000, joes said: >>>>>> >>>>>>> Am Fri, 14 Jun 2024 12:39:15 -0500 schrieb olcott: >>>>>>>> On 6/14/2024 10:54 AM, joes wrote: >>>>>>>>> Am Fri, 14 Jun 2024 08:15:52 -0500 schrieb olcott: >>>>>>>>>> On 6/14/2024 6:39 AM, Richard Damon wrote: >>>>>>>>>>> On 6/14/24 12:13 AM, olcott wrote: >>>>>>>>>>>> On 6/13/2024 10:44 PM, Richard Damon wrote: >>>>>>>>>>>>> On 6/13/24 11:14 PM, olcott wrote: >>>>>>>>>>>>>> On 6/13/2024 10:04 PM, Richard Damon wrote: >>>>>>>>>>>>>>> On 6/13/24 9:39 PM, olcott wrote: >>>>>>>>>>>>>>>> On 6/13/2024 8:24 PM, Richard Damon wrote: >>>>>>>>>>>>>>>>> On 6/13/24 11:32 AM, olcott wrote: >>>>>>> >>>>>>>>>> When H and D have a pathological relationship to each other then >>>>>>>>>> H(D,D) is not being asked about the behavior of D(D). H1(D,D) has no >>>>>>>>>> such pathological relationship thus D correctly simulated by H1 is the >>>>>>>>>> behavior of D(D). >>>>>>> What is H1 asked? >>>>>>>>> H is asked whether its input halts, and by definition should give the >>>>>>>>> (right) answer for every input. >>>>>>>> If we used that definition of decider then no human ever decided >>>>>>>> anything because every human has made at least one mistake. >>>>>>> Yes. Humans are not machines. >>>>>>>> I use the term "termination analyzer" as a close fit. The term partial >>>>>>>> halt decider is more accurate yet confuses most people. >>>>>> >>>>>> Olcott has used the term "termination analyzer", though whether he knows >>>>>> what it means is unclear. >>>>>> >>>>> >>>>> To prove (non-)termination of a C program, AProVE uses the Clang >>>>> compiler [7] to translate it to the intermediate representation of the >>>>> LLVM framework [15]. Then AProVE symbolically executes the LLVM program >>>>> and uses abstraction to obtain a finite symbolic execution graph (SEG) >>>>> containing all possible program runs. >>>> >>>> AProVE is a particular attempt, not a defintion. >>>> >>> >>> If you say: What is a duck? and I point to a duck that >>> *is* what a duck is. >> >> That would be just an example, not a definition. In particular, it does >> not tell about another being whether it can be called a "duck". >> >>> *Termination analysis* >>> In computer science, termination analysis is program analysis which >>> attempts to determine whether the evaluation of a given program halts >>> for each input. This means to determine whether the input program >>> computes a total function. >>> https://en.wikipedia.org/wiki/Termination_analysis >>> >>> I pointed out AProVE because it is essentially a simulating >>> halt decider with a limited domain. >> >> A difference between AProVE and a partial halt decider is that the input >> to AProVE is only a program but not an input to that program but the >> input to a partial halt decider contains both. >> >>>>> *AProVE: Non-Termination Witnesses for C Programs* >>>>> https://link.springer.com/content/pdf/10.1007/978-3-030-99527-0_21.pdf >> > > AProVE is a kind of simulating termination analyzer. Not really. It does not simulate. > H is a kind of simulating halt decider with a restricted domain. > [Simulating termination analyzers for dummies] makes these ideas > simpler. -- Mikko