Path: ...!news.mixmin.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: olcott Newsgroups: comp.theory,sci.logic Subject: Re: Nature of undecidable halting ---Handling undecidable inputs Date: Fri, 17 May 2024 11:49:40 -0500 Organization: A noiseless patient Spider Lines: 50 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Fri, 17 May 2024 18:49:41 +0200 (CEST) Injection-Info: dont-email.me; posting-host="269f5d410d08e21225230cab72194d27"; logging-data="2409754"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1/cKURaluEnAB/bD87KCEU7" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:42zwwB+YRXDqLp2d2HOjgvTYru4= In-Reply-To: Content-Language: en-US Bytes: 4152 On 5/17/2024 5:04 AM, Mikko wrote: > On 2024-05-16 13:20:48 +0000, joes said: > >> Am Thu, 16 May 2024 13:42:41 +0300 schrieb Mikko: >>> On 2024-05-15 15:06:26 +0000, olcott said: >>>> I refer to transitioning through a specific state to indicate a >>>> specific halt status value, for Turing Machines. >>> >>> That does not satisfy the usual definition of "halt decider". However, >>> we could accept that as a solution to the halting problem if one could >>> prove that there is a Turing machine that can indicate halting or >>> non-halting that way for all computations. >>> >>> However, it is possible to prove that every Turing machine that >>> indicates halting that way fails to indicate correctly at least some >>> computations. >> >> Are these all of the liar paradox kind, such that one could easily >> exclude them? Or do they form a more interesting class? > > The discussions hera are mainly about the liar paradox or Quine paradox > kind. They ara not always easy to exclude, and one can always modify the > code so that exclusion becomes harder but behaviour remanis the same. > Expressions that are {true on the basis of meaning} are ONLY (a) A set of finite string semantic meanings that form an accurate model of the general knowledge of the actual world. (b) Expressions derived by applying truth preserving operations to (a). The above algorithm specifies True(L,x) and False(L,x) defined as True(L, ~x). The above expressions include all of expressions of math, logic and computations specified as finite strings. The above True(L,x) combined with False(L,x) seems to screen out any any all undecidable inputs. Truthbearer(L,x) ≡ (True(L,x) ∨ False(L,x)) else type mismatch error. > There are also very different problems that are known to be uncomputable, > e.g., the problem whether a sentence in the language of the first order > goup theory is a theorem of that theory -- nothing like the liars paradox > is possible in that language. > -- Copyright 2024 Olcott "Talent hits a target no one else can hit; Genius hits a target no one else can see." Arthur Schopenhauer