Path: ...!news.misty.com!weretis.net!feeder9.news.weretis.net!news.quux.org!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail From: Richard Heathfield Newsgroups: comp.theory Subject: Re: Turing Machine computable functions apply finite string transformations to inputs Date: Wed, 30 Apr 2025 16:26:23 +0100 Organization: Fix this later Lines: 26 Message-ID: References: <87cyd5182l.fsf@nosuchdomain.example.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Date: Wed, 30 Apr 2025 17:26:24 +0200 (CEST) Injection-Info: dont-email.me; posting-host="37e133e97ee7719e4a93228f44d9117b"; logging-data="577877"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19zuBMRuh73/Zy8vZf9tkrqnTyfLaxozM5SO1Bkkv6cFA==" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:LeIsCoE58kgyo1A57yiKA4BL9vo= Content-Language: en-GB In-Reply-To: Bytes: 2163 On 30/04/2025 16:09, olcott wrote: > Turing machine computable functions must apply > finite string transformation rues to inputs > to derive outputs. > > This is not a function that computes the sum(3,2): > int sum(int x, int y) { return 5; } Here's an animated example of a TM adding two numbers (2 and 3, by a happy chance). Using building blocks like these, it is in principle possible to build an operating system. It is not, however, possible to compute an incomputable function. -- Richard Heathfield Email: rjh at cpax dot org dot uk "Usenet is a strange place" - dmr 29 July 1999 Sig line 4 vacant - apply within