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From: Dmitry A. Kazakov <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Turing-undecidable languages (OT)
Date: Wed, 08 May 2002 11:16:37 +0200
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On Tue, 7 May 2002 17:05:50 -0400, "Chad R. Meiners"
<crmeiners@hotmail.com> wrote:

><tmoran@acm.org> wrote in message
>news:7mWB8.6827$0z6.115522658@newssvr21.news.prodigy.com...
>>   If someone says "I'll write a program to do such and such", how should
>> he act differently if told:
>> a) that's recursively undecidable
>> or
>> b) your program may get stuck in an infinite loop
>
>This is an excellent question.  First, let's rephrase your question to:
>
>If some says, "I'll am going to write a program Y that solves problem X",
>how should he act if told
>
>a) X is not recursive.  (This is the same as Robert's recursively
>undecidable)
>b) Program Y may get stuck in an infinite loop.
>
>In case a, Y cannot exist.

Surely but only if Y would do no I/O and thus have no connection to
some external sources of knowledge. Consider a program that insolently
asks the operator, "hey, maybe you know the answer"? (:-))

---
Regards,
Dmitry Kazakov
www.dmitry-kazakov.de