From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Emanuel Berg Newsgroups: gmane.emacs.help Subject: Re: [External] : Re: Indentation with spaces Date: Mon, 13 Jun 2022 07:04:52 +0200 Message-ID: <875yl5m9vv.fsf@dataswamp.org> References: <87fskezg7s.fsf@dataswamp.org> <87bkuzu6dx.fsf@dataswamp.org> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="1276"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/29.0.50 (gnu/linux) To: help-gnu-emacs@gnu.org Cancel-Lock: sha1:2BV2mk/FbZiQx+Vc2W03J6Lp814= Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Mon Jun 13 07:06:08 2022 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1o0cHA-00005F-3F for geh-help-gnu-emacs@m.gmane-mx.org; Mon, 13 Jun 2022 07:06:08 +0200 Original-Received: from localhost ([::1]:45692 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1o0cH8-0006Vm-M0 for geh-help-gnu-emacs@m.gmane-mx.org; Mon, 13 Jun 2022 01:06:06 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:53858) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1o0cG6-0006Sn-E1 for help-gnu-emacs@gnu.org; Mon, 13 Jun 2022 01:05:02 -0400 Original-Received: from ciao.gmane.io ([116.202.254.214]:45650) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1o0cG4-0003zZ-H9 for help-gnu-emacs@gnu.org; Mon, 13 Jun 2022 01:05:02 -0400 Original-Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1o0cG2-0009Bn-RH for help-gnu-emacs@gnu.org; Mon, 13 Jun 2022 07:04:58 +0200 X-Injected-Via-Gmane: http://gmane.org/ Mail-Followup-To: help-gnu-emacs@gnu.org Mail-Copies-To: never Received-SPF: pass client-ip=116.202.254.214; envelope-from=geh-help-gnu-emacs@m.gmane-mx.org; helo=ciao.gmane.io X-Spam_score_int: -16 X-Spam_score: -1.7 X-Spam_bar: - X-Spam_report: (-1.7 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.249, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: "help-gnu-emacs" Xref: news.gmane.io gmane.emacs.help:137759 Archived-At: Drew Adams wrote: >> The Closed World Assumption (CWA) is the assumption that >> what is not known to be true must be false. The Open >> World Assumption (OWA) is the opposite. In other words, >> it is the assumption that what is not known to be true is >> simply unknown. >> >> Interesting! OWA seems reasonable but how did they come up >> with CWA, when is that useful > > It's simpler to reason with. If you don't know something to > be true then you conclude that it's false. This is a common > approach - databases, Prolog etc. Cf. `completing-read' with > arg REQIUIRE-MATCH = t. > > Of course, one can interpret "no match" as just "dunno" or > "unproven", but often it's acted on as "false". And as Tomas > perhaps hinted, it's not just about classifying as true, > false, and dunno. > > It's about the difference between any such closed > classification and a representation or system that's based > on the idea that both (a) the set of stuff that's classified > and (b) the classification of that stuff both (1) are > inherently incomplete and (2) can change. > > CWA is akin to not-proven-guilty-means-innocent (or > not-proven-innocent-means-guilty). OWA assumes only that > not-proven means not-proven. > >> and what's closed about it, > > It doesn't allow for the possibility that there are > unknowns. It assumes that, at any time, what's known to be > true is all there is. > > It's a useful simplification. But it presents difficulties > wrt the nature of real knowledge and its evolution. > >> that you know what you know to be true and every thing else >> you then and by that can tell is false. So it's a complete >> state of the knowledge sphere, that's what's closed >> about it? > > Exactly. At any given time. And a system that allows for > increasing or changing knowledge has somehow to deal with > non-monotonic changes in what's known (in particular). I understand, thanks. -- underground experts united https://dataswamp.org/~incal