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: g2news1.google.com!news4.google.com!proxad.net!feeder1-2.proxad.net!newsfeed.straub-nv.de!news.k-dsl.de!news.uni-stuttgart.de!news.stw-bonn.de!news-koe1.dfn.de!news-lei1.dfn.de!news.uni-weimar.de!not-for-mail From: stefan-lucks@see-the.signature Newsgroups: comp.lang.ada Subject: Re: and then... (a curiosity) Date: Thu, 4 Sep 2008 21:05:02 +0200 Organization: Bauhaus-Universitaet Weimar Message-ID: References: <18b41828-bda4-4484-8884-ad62ce1c831d@f36g2000hsa.googlegroups.com> <57qdnfULQ9tzKCHVnZ2dnUVZ_tHinZ2d@comcast.com> <48bd0003$1@news.post.ch> <12prmxev8newf.lvc4m055okkb$.dlg@40tude.net> Reply-To: stefan-lucks@see-the.signature NNTP-Posting-Host: medsec1.medien.uni-weimar.de Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Trace: tigger.scc.uni-weimar.de 1220550790 29862 141.54.178.228 (4 Sep 2008 17:53:10 GMT) X-Complaints-To: news@tigger.scc.uni-weimar.de NNTP-Posting-Date: Thu, 4 Sep 2008 17:53:10 +0000 (UTC) X-X-Sender: lucks@medsec1.medien.uni-weimar.de In-Reply-To: Xref: g2news1.google.com comp.lang.ada:1919 Date: 2008-09-04T21:05:02+02:00 List-Id: > >> 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. You are trying to build an overly complex theory, which I am not interested in. The issue is very simple: 1. If the A- or the B-part in "if A and B" raises an exception, but the other part is false, the "right thing" (TM) to do would be to transfer control to the else clause (or below "end if", when there is no else). The intermediate result can be viewed as a three-valued logic expression, but the final outcome of the Boolean expression must be Boolean, of course. 2. If both raise A and B an exception, of if one raises an exception and the other one is true, an exception is propagated. (*) 3. I would be willing to pragmatically sacrifice mathematical purity for a shortcut rule: If A is false, the expression is false, whatever B does. If A raises an exception, of if A is true and B raises an exception, the exception is propagated. ---- (*) Funny problem: *Which* exception should be propagated? -- ------ Stefan Lucks -- Bauhaus-University Weimar -- Germany ------ Stefan dot Lucks at uni minus weimar dot de ------ I love the taste of Cryptanalysis in the morning! ------