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	<title>Anima Ex Machina &#124; Hector Zenil's blog &#187; Computability, Universality and Unsolvability</title>
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	<description>Hector Zenil's blog on foundations, metamathematics and computation</description>
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		<title>Physics-like computation, Wolfram&#8217;s PCE and Church&#8217;s thesis</title>
		<link>http://www.mathrix.org/liquid/archives/physics-like-computation-wolframs-principle-of-computational-and-churchs-thesis</link>
		<comments>http://www.mathrix.org/liquid/archives/physics-like-computation-wolframs-principle-of-computational-and-churchs-thesis#comments</comments>
		<pubDate>Wed, 07 Jan 2009 20:32:31 +0000</pubDate>
		<dc:creator>Hector Zenil</dc:creator>
				<category><![CDATA[Computability, Universality and Unsolvability]]></category>
		<category><![CDATA[Foundations of Computation]]></category>
		<category><![CDATA[General]]></category>
		<category><![CDATA[physics of computation]]></category>
		<category><![CDATA[Principle of Computational Equivalence]]></category>

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The lack of correspondence between the abstract and the physical world seems sometimes to suggest that there are profound incompatibilities between what can be thought and what actually happens in the real world. One can ask, for example, how often one faces undecidable problems. However, the question of undecidability has been considered to be better [...]]]></description>
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		<title>The Shortest Universal Turing Machine Implementation Contest</title>
		<link>http://www.mathrix.org/liquid/archives/the-shortest-universal-turing-machine-implementation-contest</link>
		<comments>http://www.mathrix.org/liquid/archives/the-shortest-universal-turing-machine-implementation-contest#comments</comments>
		<pubDate>Mon, 22 Dec 2008 23:52:23 +0000</pubDate>
		<dc:creator>Hector Zenil</dc:creator>
				<category><![CDATA[Algorithmic information theory]]></category>
		<category><![CDATA[Complexity]]></category>
		<category><![CDATA[Computability, Universality and Unsolvability]]></category>
		<category><![CDATA[Foundations of Computation]]></category>
		<category><![CDATA[New Ideas]]></category>
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		<category><![CDATA[Add new tag]]></category>
		<category><![CDATA[Turing machine]]></category>

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		<description><![CDATA[========================================
The Shortest Universal Turing Machine Implementation Contest
                          ANNOUNCEMENT
                          23 Dec &#8211; 2008
  http://www.mathrix.org/experimentalAIT/TuringMachine.html
========================================
Contest Overview
============
In the spirit of the busy beaver competition though related to program-size complexity, we are pleased to announce the &#8220;Shortest Universal [...]]]></description>
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		<title>On the simplest and smallest universal Turing machine</title>
		<link>http://www.mathrix.org/liquid/archives/the-simplest-and-smallest-universal-turing-machine-was-found</link>
		<comments>http://www.mathrix.org/liquid/archives/the-simplest-and-smallest-universal-turing-machine-was-found#comments</comments>
		<pubDate>Tue, 30 Oct 2007 03:03:27 +0000</pubDate>
		<dc:creator>Hector Zenil</dc:creator>
				<category><![CDATA[Complexity]]></category>
		<category><![CDATA[Computability, Universality and Unsolvability]]></category>
		<category><![CDATA[Computer Science]]></category>
		<category><![CDATA[Foundations of Computation]]></category>
		<category><![CDATA[General]]></category>
		<category><![CDATA[computational complexity]]></category>
		<category><![CDATA[NKS]]></category>
		<category><![CDATA[Principle of Computational Equivalence]]></category>
		<category><![CDATA[Turing machine]]></category>
		<category><![CDATA[universality]]></category>

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		<description><![CDATA[Why research on the universality of the Wolfram 2,3 Turing machine (http://www.wolframscience.com/prizes/tm23/) and the small universal Turing machine  is relevant for modern computer science:
* New techniques for proving universality are being developed (Alex Smith&#8217;s novel approach for unbounded computations from arbitrary lengths and non-periodic initial configurations).
* Completely new universal systems have been discovered (cyclic tag- [...]]]></description>
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		<title>Seth Lloyd&#8217;s answers to my questions</title>
		<link>http://www.mathrix.org/liquid/archives/seth-lloyd-answers-to-my-questions</link>
		<comments>http://www.mathrix.org/liquid/archives/seth-lloyd-answers-to-my-questions#comments</comments>
		<pubDate>Wed, 22 Nov 2006 00:12:39 +0000</pubDate>
		<dc:creator>Hector Zenil</dc:creator>
				<category><![CDATA[Complexity]]></category>
		<category><![CDATA[Computability, Universality and Unsolvability]]></category>
		<category><![CDATA[Conferences]]></category>
		<category><![CDATA[Minds and Machines]]></category>
		<category><![CDATA[AIT]]></category>
		<category><![CDATA[Berlin]]></category>
		<category><![CDATA[Church-Turing thesis]]></category>
		<category><![CDATA[quantum computer]]></category>
		<category><![CDATA[quantum computing]]></category>
		<category><![CDATA[quantum mechanics]]></category>
		<category><![CDATA[randomness]]></category>
		<category><![CDATA[Seth Lloyd]]></category>
		<category><![CDATA[universe is a computer]]></category>

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The original questions were posted here.
From Dr. Seth Lloyd&#8217;s answers it is clear that:
1) he is assuming the Deutsch quantum computing model, which is Turing reducible and
2) he is assuming that quantum particles encode a finite amount of information, so that they are completely discrete in every possible sense, including: space/time, mass, energy, momentum, and any [...]]]></description>
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		<title>Is the Universe a Computer? (Ist das Universum ein Computer?) Conference, Berlin, Germany, 6,7 November 2006</title>
		<link>http://www.mathrix.org/liquid/archives/is-the-universe-a-computer-ist-das-universum-ein-computer-conference-berlin-germany-67-november-2006</link>
		<comments>http://www.mathrix.org/liquid/archives/is-the-universe-a-computer-ist-das-universum-ein-computer-conference-berlin-germany-67-november-2006#comments</comments>
		<pubDate>Sun, 12 Nov 2006 01:55:57 +0000</pubDate>
		<dc:creator>Hector Zenil</dc:creator>
				<category><![CDATA[Computability, Universality and Unsolvability]]></category>
		<category><![CDATA[Conferences]]></category>
		<category><![CDATA[Minds and Machines]]></category>
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		<category><![CDATA[Berlin]]></category>
		<category><![CDATA[Carl Adam Petri]]></category>
		<category><![CDATA[Konrad Zuse]]></category>
		<category><![CDATA[Kovas Boguta]]></category>
		<category><![CDATA[quantum computers]]></category>
		<category><![CDATA[Seth Lloyd]]></category>
		<category><![CDATA[universe is a computer]]></category>

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		<description><![CDATA[
Ist das Universum ein Computer?
http://www.dtmb.de/Aktuelles/Aktionen/Informatikjahr-Zuse/
Germany, November 2006, Informatik Jahr
Deutschen Technikmuseum Berlin
From Konrad Zuse&#8217;s Invention of the Computer to his &#8220;Calculating Space&#8221; to Quantum Computing.
Lesson One: For someone with a hammer in his hand the world seems to be a  nail. Joseph Weizenbaun.
Lesson Two: Knowing the input and the transition function of a Turing machine we [...]]]></description>
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