Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!wuarchive!udel!haven.umd.edu!socrates.umd.edu!socrates!rockwell From: rockwell@socrates.umd.edu (Raul Rockwell) Newsgroups: comp.lang.misc Subject: Re: Halting Problem Solved! Film at 11! (Was Re: definitions) Message-ID: Date: 14 May 91 13:16:34 GMT References: <30275@dime.cs.umass.edu> <1991May14.054813.18427@sbcs.sunysb.edu> Sender: rockwell@socrates.umd.edu (Raul Rockwell) Organization: Traveller Lines: 26 In-Reply-To: jallen@csserv2.ic.sunysb.edu's message of 14 May 91 05: 48:13 GMT >Victor Yodaiken: >>But, there is no theoretical reason why a clever design could not >>produce a useful programming language with a compiler that >>verified termination. David A. Truesdell: >The answer to the question is "NO". It is not possible in >practice, it is not possible in theory. Joseph Allen: No, it can be done! Really! Just don't allow loops, gotos or recursion. Now who wants to write a compiler in a language with these restrictions? Well, you can allow loops as long as they can guaranteed to be bounded. And you don't really need a new compiler, just take an existing one and remove anything which allows unbounded loops or recursion. I suppose such a thing could be quite instructive. Ask the question "how useful is this language when I remove everything which potentially prevents halting?". If nothing else, it might tell you where the language designers were at. Raul Rockwell