Path: news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail From: Mikko Newsgroups: sci.logic Subject: Re: The key undecidable instance that I know about --- Truth-bearers ONLY Date: Tue, 11 Mar 2025 12:50:16 +0200 Organization: - Lines: 76 Message-ID: References: <3b57384a57c71e1880fe3f1df975003c1d743c07@i2pn2.org> <9a2fbcc7a803bc91d320117f8c8e03e03799e9b3@i2pn2.org> <95ca0b344ae29f6911a73c655ddbe1c7214f8519@i2pn2.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Tue, 11 Mar 2025 11:50:16 +0100 (CET) Injection-Info: dont-email.me; posting-host="ac66f5fd211d01a7df4319119304e545"; logging-data="2039666"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+S917putM34ux80kLQjS85" User-Agent: Unison/2.2 Cancel-Lock: sha1:UWMZGNgllQHvL0CNV7vE280I9eA= On 2025-03-11 03:23:51 +0000, olcott said: > On 3/10/2025 9:49 PM, dbush wrote: >> On 3/10/2025 10:39 PM, olcott wrote: >>> On 3/10/2025 9:21 PM, Richard Damon wrote: >>>> On 3/10/25 9:45 PM, olcott wrote: >>>>> On 3/10/2025 5:45 PM, Richard Damon wrote: >>>>>> On 3/9/25 11:39 PM, olcott wrote: >>>>>>> >>>>>>> LP := ~True(LP)  DOES SPECIFY INFINITE RECURSION. >>>>>> >>>>>> WHich is irrelevent, as that isn't the statement in view, only what >>>>>> could be shown to be a meaning of the actual statement. >>>>>> >>>>> >>>>> The Liar Paradox PROPERLY FORMALIZED Infinitely recursive >>>>> thus semantically incorrect. >>>> >>>> But is irrelevent to your arguement. >>>> >>>> >>>>> >>>>> "It would then be possible to reconstruct the antinomy of the liar >>>>>   in the metalanguage, by forming in the language itself a sentence" >>>> >>>> Right, the "Liar" is in the METALANGUAGE, not the LANGUAGE where the >>>> predicate is defined. >>>> >>>> You are just showing you don't understand the concept of Metalanguage. >>>> >>>>> >>>>> Thus anchoring his whole proof in the Liar Paradox even if >>>>> you do not understand the term "metalanguage" well enough >>>>> to know this. >>>> >>>> Yes, there is a connection to the liar's paradox, and that is that he >>>> shows that the presumed existance of a Truth Predicate forces the logic >>>> system to have to resolve the liar's paradox. >>>> >>> >>> bool True(X) >>> { >>>    if (~unify_with_occurs_check(X)) >>>      return false; >>>    else if (~Truth_Bearer(X)) >>>     return false; >>>    else >>>     return IsTrue(X); >>> } >>> >>> LP := ~True(LP) >>> True(LP) resolves to false. >> >> ~True(LP) resolves to true > > It may seem that way if you fail to understand > Clocksin & Mellish explanation of > > Most Prolog systems will allow you to > satisfy goals like: > equal(X, X). > ?- equal(foo(Y), Y). > > that is, they will allow you to match a > term against an uninstantiated subterm of itself. > > ON PAGE 3 > https://www.researchgate.net/publication/350789898_Prolog_detects_and_rejects_pathological_self_reference_in_the_Godel_sentence > That you can quote some text but don't say anything about it supports the hypthesis that you don't understand the text you quoted. -- Mikko