From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-0.3 required=5.0 tests=BAYES_00, REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4 X-Google-Thread: 103376,99e73f65ea2533b9 X-Google-Attributes: gid103376,domainid0,public,usenet X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news2.google.com!news2.google.com!news.glorb.com!newsfeed-0.progon.net!progon.net!newsfeed.ision.net!newsfeed2.easynews.net!ision!newsfeed.arcor.de!newsspool1.arcor-online.net!news.arcor.de.POSTED!not-for-mail From: "Dmitry A. Kazakov" Subject: Re: and then... (a curiosity) Newsgroups: comp.lang.ada User-Agent: 40tude_Dialog/2.0.15.1 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Reply-To: mailbox@dmitry-kazakov.de Organization: cbb software GmbH References: <18b41828-bda4-4484-8884-ad62ce1c831d@f36g2000hsa.googlegroups.com> <57qdnfULQ9tzKCHVnZ2dnUVZ_tHinZ2d@comcast.com> <48bd0003$1@news.post.ch> <12prmxev8newf.lvc4m055okkb$.dlg@40tude.net> Date: Thu, 4 Sep 2008 15:00:23 +0200 Message-ID: NNTP-Posting-Date: 04 Sep 2008 15:00:23 CEST NNTP-Posting-Host: 8186e4d7.newsspool1.arcor-online.net X-Trace: DXC=o0Y_LFMFZGe]BlmkiiU@Biic==]BZ:afn4Fo<]lROoRa4nDHegD_]ReE1^m\L^eUifDNcfSJ;bb[eFCTGGVUmh?dLK[5LiR>kgbABVlI<_O]Zh X-Complaints-To: usenet-abuse@arcor.de Xref: g2news2.google.com comp.lang.ada:7640 Date: 2008-09-04T15:00:23+02:00 List-Id: On Thu, 4 Sep 2008 14:04:10 +0200, stefan-lucks@see-the.signature wrote: >> Well, indeed >> >> 0 /\ _|_ = 0 >> 0 /\ T = 0 >> >> Here 0 = False, 1 = True, _|_ = Uncertain, T = Contradiction. False under >> /\ always renders False. >> >> Nevertheless Boolean logic /= Belnap logic, though the former is contained >> in the latter. > > I never said "Boolean logic", I said "logic", which was ment to include > multi-valued logic. ;-) There are many multi-valued logics. But the problem is that taking such a logic for the base, you need to reconsider everything based on inference. In such logics inference is sufficiently more difficult, especially when the results need to be interpreted. The Boolean type is heavily used in the language. As an example, consider "when others" of a case statement. It uses the reasoning if X not in A then X in not A (not A = the complement set of A). But when "in A" is uncertain then its counterpart is too. How case is supposed to work, then? In fact, especially evident it becomes in fuzzy logic, in such frameworks you need to keep track on multiple competing alternatives, because at no point you can discard anything different from False. On the contrary, in Boolean logic there is only one right path. -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de