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From: ags@pucc-h (Dave Seaman)
Newsgroups: net.math
Subject: Re: Omega
Message-ID: <2565@pucc-h>
Date: Thu, 23-Jan-86 09:07:20 EST
Article-I.D.: pucc-h.2565
Posted: Thu Jan 23 09:07:20 1986
Date-Received: Sat, 25-Jan-86 08:52:28 EST
References: <440@faron.UUCP>
Reply-To: ags@pucc-h.UUCP (Dave Seaman)
Distribution: net
Organization: Purdue University Computing Center
Lines: 16

In article <440@faron.UUCP> bs@faron.UUCP (Robert D. Silverman) writes:
>Does anyone have any references concerning the (relatively) new constant
>called omega? Omega is the exact probability that a random input tape
>fed to a deterministic Turing machine will cause the machine to halt.

One of Martin Gardner's last columns for Scientific American contained
a discussion of this constant.  I believe the definition is somewhat more
complex than you indicate, since it consists of powers of two summed in
such a way that, if you knew the exact value, you could decode it to
determine whether any particular input tape will cause the machine to halt.

>I believe that it has been shown that omega is not computable.

Obviously.  
-- 
Dave Seaman	  					pur-ee!pucc-h!ags