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=-1.9 required=5.0 tests=BAYES_00,FREEMAIL_FROM autolearn=ham autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f849b,b8d52151b7b306d2 X-Google-Attributes: gidf849b,public X-Google-Thread: 103376,a00006d3c4735d70 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2004-01-11 18:20:20 PST Path: archiver1.google.com!news2.google.com!news.maxwell.syr.edu!newsfeed.media.kyoto-u.ac.jp!newsfeed.icl.net!newsfeed.fjserv.net!news-FFM2.ecrc.net!nntp.abs.net!ash.uu.net!news.tufts.edu!elk.ncren.net!nntp.upenn.edu!msunews!not-for-mail From: "Chad R. Meiners" Newsgroups: comp.arch.embedded,comp.lang.ada Subject: Re: Certified C compilers for safety-critical embedded systems Date: Sun, 11 Jan 2004 21:13:53 -0500 Organization: Michigan State University Message-ID: References: <3fe00b82.90228601@News.CIS.DFN.DE> <3ff18d4d.603356952@News.CIS.DFN.DE> <1731094.1f7Irsyk1h@linux1.krischik.com> <3ff1b8ef.614528516@News.CIS.DFN.DE> <3FF1E06D.A351CCB4@yahoo.com> <3ff20cc8.635997032@News.CIS.DFN.DE> NNTP-Posting-Host: arctic.cse.msu.edu X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2800.1158 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 Xref: archiver1.google.com comp.arch.embedded:7297 comp.lang.ada:4345 Date: 2004-01-11T21:13:53-05:00 List-Id: "Georg Bauhaus" wrote in message news:btsrnj$gld$2@a1-hrz.uni-duisburg.de... > In comp.lang.ada Chad R. Meiners wrote: > : > : "Robert I. Eachus" wrote in message > : news:tP2dndMsaLDKEpzd4p2dnA@comcast.com... > :> Chad R. Meiners wrote: > :> > :> > Not always true---we can specify the Halting problem (for a Turing > :> > Equavilent machine), but we cannot implement it without an oracle. > :> > :> Actually not quite true. It is not hard to write a program that > :> implements the Halting problem, and for any finite machine, it will > :> always return the correct answer. > : > : This would be a specification for the Halting problem for a bounded Turing > : Machine. > > Are you sure you can say that a program that implements the Halting > problem for a bounded Turing machine does not implement the same > problem for a Turing machine? Of course you can SAY it! I just did ;-) It depends what you mean by implement. I tend to think of implementations as algorithms (which must halt). Therefore, since there is no algorithm that satisfies the Halting problem's specification (it is undecidable), there is not an implementation. If you want to define implementation as something else (reasonable or unreasonable), all bets are off of course. -CRM