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,FREEMAIL_FROM, REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,c42dbf68f5320193 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2002-05-06 08:46:31 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!logbridge.uoregon.edu!paloalto-snh1.gtei.net!cambridge1-snf1.gtei.net!news.gtei.net!bos-service1.ext.raytheon.com!bos-service2.ext.raytheon.com.POSTED!not-for-mail Message-ID: <3CD6A550.6C8AE20F@despammed.com> From: Wes Groleau Reply-To: wesgroleau@despammed.com X-Mailer: Mozilla 4.77 [en] (Windows NT 5.0; U) X-Accept-Language: en,es-MX,es,pt,fr-CA,fr MIME-Version: 1.0 Newsgroups: comp.lang.ada Subject: Re: Generation of permutations References: <5ee5b646.0205041652.63032ba6@posting.google.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Date: Mon, 06 May 2002 10:46:24 -0500 NNTP-Posting-Host: 151.168.144.162 X-Complaints-To: news@ext.ray.com X-Trace: bos-service2.ext.raytheon.com 1020699991 151.168.144.162 (Mon, 06 May 2002 11:46:31 EDT) NNTP-Posting-Date: Mon, 06 May 2002 11:46:31 EDT Organization: Raytheon Company Xref: archiver1.google.com comp.lang.ada:23586 Date: 2002-05-06T10:46:24-05:00 List-Id: > > > but to determine whether a set of instructions constitutes a general > > > sorting algorithm is obviously recursively undecidable. > > So the set of instructions emitted by Gnat when it compiles bubble sort > > code may or may not constitute a general sorting algorithm, and whether > > it does or not is undecidable? I learn something new every day. > > No that is not what Robert was saying. He was referring to Rice's Theorem > for which you can clearly show that the problem of determining whether a > given set of machine instructions will sort an given input is > Turing-undecidable. How did you come to such a misinterpretation? "given set of machine instructions" => "instructions emitted by Gnat when it compiles bubble sort" "determining whether ... will sort an given input " => "may or may not constitute a general sorting algorithm" What did I miss ? -- Wes Groleau http://freepages.rootsweb.com/~wgroleau