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,DIET_1,FREEMAIL_FROM autolearn=ham autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,a00006d3c4735d70 X-Google-Attributes: gid103376,public X-Google-Thread: f849b,b8d52151b7b306d2 X-Google-Attributes: gidf849b,public X-Google-ArrivalTime: 2004-01-11 10:00:56 PST Path: archiver1.google.com!news2.google.com!news.maxwell.syr.edu!newsfeed.mathworks.com!wn11feed!worldnet.att.net!216.166.71.14!border3.nntp.aus1.giganews.com!intern1.nntp.aus1.giganews.com!nntp.giganews.com!nntp.comcast.com!news.comcast.com.POSTED!not-for-mail NNTP-Posting-Date: Sun, 11 Jan 2004 12:00:54 -0600 Date: Sun, 11 Jan 2004 13:00:54 -0500 From: "Robert I. Eachus" User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.4) Gecko/20030624 Netscape/7.1 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 Newsgroups: comp.arch.embedded,comp.lang.ada Subject: Re: Certified C compilers for safety-critical embedded systems References: <3fe00b82.90228601@News.CIS.DFN.DE> <5802069.JsgInS3tXa@linux1.krischik.com> <1072464162.325936@master.nyc.kbcfp.com> <1563361.SfB03k3vvC@linux1.krischik.com> <11LvOkBBXw7$EAJw@phaedsys.demon.co.uk> <3ff0687f.528387944@News.CIS.DFN.DE> <1086072.fFeiH4ICbz@linux1.krischik.com> <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> Organization: LJK Software In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Message-ID: NNTP-Posting-Host: 24.34.214.193 X-Trace: sv3-wW7IR4izoRKH58Ef+1X2TTt+olN2GlTfxCUJL0gIhqdZRPcossLCMDZHkNWaXFLdoVFkuRsVH5h3tsI!TH4rfwDzCTOB1wREJnWrjtv7fgHDUVN6pxoMaIHN7ScPa+uuK90WduI7Tggxiw== X-Complaints-To: abuse@comcast.net X-DMCA-Complaints-To: dmca@comcast.net X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.1 Xref: archiver1.google.com comp.arch.embedded:7274 comp.lang.ada:4338 Date: 2004-01-11T13:00:54-05:00 List-Id: 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. If you allow the number of intermediate states for programs submitted to be unbounded, then you cannot bound the execution time for the (combination of) program and machine that implements the Halting problem. The Halting problem and a real time constraint is an impossible combination. For that matter, anyone who works with hard real-time knows that you have to allow for the possibility that all of the constraints on the system cannot be met. Then you have to do the engineering part of the job and select the right tradeoff. (Which may include a higher power budget or extra weight, or even more money so you can build a custom chip.) -- Robert I. Eachus "The war on terror is a different kind of war, waged capture by capture, cell by cell, and victory by victory. Our security is assured by our perseverance and by our sure belief in the success of liberty." -- George W. Bush