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Path: ...!eternal-september.org!feeder2.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Mikko <mikko.levanto@iki.fi> Newsgroups: sci.logic Subject: Re: A different perspective on undecidability --- incorrect question Date: Sat, 26 Oct 2024 10:52:35 +0300 Organization: - Lines: 76 Message-ID: <vfi743$3kr1e$1@dont-email.me> References: <veoift$29dtl$2@dont-email.me> <veoq3j$2aqp2$1@dont-email.me> <vf716u$1607j$1@dont-email.me> <vf7ks8$1d1vt$1@dont-email.me> <vf8eu5$1h5mj$2@dont-email.me> <vfdk8g$2lgl1$1@dont-email.me> <vfdrb8$2mcdg$1@dont-email.me> <vffk1i$33iat$1@dont-email.me> <vfgaev$36im7$5@dont-email.me> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Sat, 26 Oct 2024 09:52:36 +0200 (CEST) Injection-Info: dont-email.me; posting-host="ceca57aa9cd2f8b0738fdd62214a72ea"; logging-data="3828782"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX18SHfxZh14hRJz/0aqOPPZP" User-Agent: Unison/2.2 Cancel-Lock: sha1:4OM504qSTKmA48UkSnV9nUY11Ks= Bytes: 4219 On 2024-10-25 14:37:19 +0000, olcott said: > On 10/25/2024 3:14 AM, Mikko wrote: >> On 2024-10-24 16:07:03 +0000, olcott said: >> >>> On 10/24/2024 9:06 AM, Mikko wrote: >>>> On 2024-10-22 15:04:37 +0000, olcott said: >>>> >>>>> On 10/22/2024 2:39 AM, Mikko wrote: >>>>>> On 2024-10-22 02:04:14 +0000, olcott said: >>>>>> >>>>>>> On 10/16/2024 11:37 AM, Mikko wrote: >>>>>>>> On 2024-10-16 14:27:09 +0000, olcott said: >>>>>>>> >>>>>>>>> The whole notion of undecidability is anchored in ignoring the fact that >>>>>>>>> some expressions of language are simply not truth bearers. >>>>>>>> >>>>>>>> A formal theory is undecidable if there is no Turing machine that >>>>>>>> determines whether a formula of that theory is a theorem of that >>>>>>>> theory or not. Whether an expression is a truth bearer is not >>>>>>>> relevant. Either there is a valid proof of that formula or there >>>>>>>> is not. No third possibility. >>>>>>>> >>>>>>> >>>>>>> After being continually interrupted by emergencies >>>>>>> interrupting other emergencies... >>>>>>> >>>>>>> If the answer to the question: Is X a formula of theory Y >>>>>>> cannot be determined to be yes or no then the question >>>>>>> itself is somehow incorrect. >>>>>> >>>>>> There are several possibilities. >>>>>> >>>>>> A theory may be intentionally incomplete. For example, group theory >>>>>> leaves several important question unanswered. There are infinitely >>>>>> may different groups and group axioms must be true in every group. >>>>>> >>>>>> Another possibility is that a theory is poorly constructed: the >>>>>> author just failed to include an important postulate. >>>>>> >>>>>> Then there is the possibility that the purpose of the theory is >>>>>> incompatible with decidability, for example arithmetic. >>>>>> >>>>>>> An incorrect question is an expression of language that >>>>>>> is not a truth bearer translated into question form. >>>>>>> >>>>>>> When "X a formula of theory Y" is neither true nor false >>>>>>> then "X a formula of theory Y" is not a truth bearer. >>>>>> >>>>>> Whether AB = BA is not answered by group theory but is alwasy >>>>>> true or false about specific A and B and universally true in >>>>>> some groups but not all. >>>>> >>>>> See my most recent reply to Richard it sums up >>>>> my position most succinctly. >>>> >>>> We already know that your position is uninteresting. >>>> >>> >>> Don't want to bother to look at it (AKA uninteresting) is not at >>> all the same thing as the corrected foundation to computability >>> does not eliminate undecidability. >> >> No, but we already know that you don't offer anything interesting >> about foundations to computability or undecidabilty. > > In the same way that ZFC eliminated RP True_Olcott(L,x) > eliminates undecidability. Not bothering to pay attention > is less than no rebuttal what-so-ever. No, not in the same way. ZFC is a useful set theory for many purposes. You don't offer any useful theory for any purpose. -- Mikko