Newsgroups: comp.ai
Path: cantaloupe.srv.cs.cmu.edu!rochester!cornellcs!newsstand.cit.cornell.edu!news.kei.com!newsfeed.internetmci.com!howland.reston.ans.net!EU.net!peer-news.britain.eu.net!newsfeed.ed.ac.uk!ainews!aisb!timt
From: timt@aisb.ed.ac.uk (Tim Taylor)
Subject: Proof of Computational Universality?
Message-ID: <DJuIJD.19H@aisb.ed.ac.uk>
Sender: timt@radon (Tim Taylor)
Organization: Dept AI, Edinburgh University, Scotland
Date: Tue, 19 Dec 1995 18:11:36 GMT
Lines: 23

Any help with the following would be much appreciated:

What are the necessary features of a system for it to be capable of
universal computation? Indeed, can the requirements be specified this
simply? Also, is the term "computational universality" (CU)
interchangable with "Turing equivalence"?

As far as I understood, if a system was capable of performing
the operations NOT, OR and IF (and assuming infinite available
memory), then it was CU. However, it has been suggested that some
combination of stacks and/or registers is also required - on
reflection this seems another fairly obvious requirement. Are
there any more necessary features? Can anyone give me a formal 
definition of the requirements?

Thanks,

Tim.

--------------------------------------------------------------------------
Tim Taylor, Department of Artificial Intelligence, University of Edinburgh
             tel +44-(0)131-650-3084/3081/4493 fax -650-6899
             home page http://www.dai.ed.ac.uk/students/timt
