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	<title>Comments on: Ask me (almost) anything</title>
	<link>http://scottaaronson.com/blog/?p=416</link>
	<description>The Blog of Scott Aaronson</description>
	<pubDate>Fri, 10 Sep 2010 05:11:56 +0000</pubDate>
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		<title>By: Scott</title>
		<link>http://scottaaronson.com/blog/?p=416#comment-36197</link>
		<author>Scott</author>
		<pubDate>Wed, 19 Aug 2009 15:59:20 +0000</pubDate>
		<guid>http://scottaaronson.com/blog/?p=416#comment-36197</guid>
		<description>Vadim P. (#176):

&lt;i&gt;Scott, I’d like to know if you’ve ever thought about writing a book on complexity, especially an introductory one.&lt;/i&gt;

I've done more than think about it!  Within a year or so, Cambridge University Press will be publishing a book based on my Quantum Computing Since Democritus lectures.</description>
		<content:encoded><![CDATA[<p>Vadim P. (#176):</p>
<p><i>Scott, I’d like to know if you’ve ever thought about writing a book on complexity, especially an introductory one.</i></p>
<p>I&#8217;ve done more than think about it!  Within a year or so, Cambridge University Press will be publishing a book based on my Quantum Computing Since Democritus lectures.</p>
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		<title>By: Scott</title>
		<link>http://scottaaronson.com/blog/?p=416#comment-36196</link>
		<author>Scott</author>
		<pubDate>Wed, 19 Aug 2009 15:51:11 +0000</pubDate>
		<guid>http://scottaaronson.com/blog/?p=416#comment-36196</guid>
		<description>Joe C. (#33):

&lt;i&gt;What about quantum complexity, QIS… What are good introductory books?&lt;/i&gt;

Sorry for the long delay!  I recommend David Mermin's "Quantum Computer Science" for complete beginners, and then the Nielsen &#038; Chuang book.

The Feynman Lectures are ... well, the Feynman Lectures, among the greatest physics books ever written.  Just don't expect to learn about quantum computing / information from them.</description>
		<content:encoded><![CDATA[<p>Joe C. (#33):</p>
<p><i>What about quantum complexity, QIS… What are good introductory books?</i></p>
<p>Sorry for the long delay!  I recommend David Mermin&#8217;s &#8220;Quantum Computer Science&#8221; for complete beginners, and then the Nielsen &#038; Chuang book.</p>
<p>The Feynman Lectures are &#8230; well, the Feynman Lectures, among the greatest physics books ever written.  Just don&#8217;t expect to learn about quantum computing / information from them.</p>
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		<title>By: Scott</title>
		<link>http://scottaaronson.com/blog/?p=416#comment-36195</link>
		<author>Scott</author>
		<pubDate>Wed, 19 Aug 2009 15:45:11 +0000</pubDate>
		<guid>http://scottaaronson.com/blog/?p=416#comment-36195</guid>
		<description>Different Joe (#165):

&lt;i&gt;What do you think of K. Mulmuley’s (of UChicago) approach to P vs. NP via GCT?&lt;/i&gt;

I'm planning a whole blog post about it---stay tuned!</description>
		<content:encoded><![CDATA[<p>Different Joe (#165):</p>
<p><i>What do you think of K. Mulmuley’s (of UChicago) approach to P vs. NP via GCT?</i></p>
<p>I&#8217;m planning a whole blog post about it&#8212;stay tuned!</p>
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		<title>By: Scott</title>
		<link>http://scottaaronson.com/blog/?p=416#comment-36194</link>
		<author>Scott</author>
		<pubDate>Wed, 19 Aug 2009 15:43:23 +0000</pubDate>
		<guid>http://scottaaronson.com/blog/?p=416#comment-36194</guid>
		<description>Anon (#179): Looks cool!  Wish I knew enough to say more.</description>
		<content:encoded><![CDATA[<p>Anon (#179): Looks cool!  Wish I knew enough to say more.</p>
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		<title>By: Scott</title>
		<link>http://scottaaronson.com/blog/?p=416#comment-36193</link>
		<author>Scott</author>
		<pubDate>Wed, 19 Aug 2009 15:36:54 +0000</pubDate>
		<guid>http://scottaaronson.com/blog/?p=416#comment-36193</guid>
		<description>Sim (#189):

&lt;i&gt;Scott, would you be kind enough to provide a “Shor, I’ll do it”-like demonstration of how to reduce an instance of a travelling salesman problem into an instance of a graph coloring problem? Please, it’s my birthday! :-)&lt;/i&gt;

Happy birthday!!  But on your next birthday, could you ask for something less wince-inducing? :-)

Alright, alright, here's an outline:

First reduce Traveling Salesman to SAT.  (That this is doable follows immediately from the Cook-Levin Theorem.)

Next reduce SAT to 3SAT.  (That's a simple reduction, as pointed out in Cook's original paper.)

Finally reduce 3SAT to coloring.  (That's a standard gadget construction---it's even covered in my GITCS notes, linked to on the sidebar of this blog.)

For more read Garey &#038; Johnson, or google for lecture notes about NP-completeness until you find ones that you like.</description>
		<content:encoded><![CDATA[<p>Sim (#189):</p>
<p><i>Scott, would you be kind enough to provide a “Shor, I’ll do it”-like demonstration of how to reduce an instance of a travelling salesman problem into an instance of a graph coloring problem? Please, it’s my birthday! <img src='http://scottaaronson.com/blog/wp-includes/images/smilies/icon_smile.gif' alt=':-)' class='wp-smiley' /> </i></p>
<p>Happy birthday!!  But on your next birthday, could you ask for something less wince-inducing? <img src='http://scottaaronson.com/blog/wp-includes/images/smilies/icon_smile.gif' alt=':-)' class='wp-smiley' /> </p>
<p>Alright, alright, here&#8217;s an outline:</p>
<p>First reduce Traveling Salesman to SAT.  (That this is doable follows immediately from the Cook-Levin Theorem.)</p>
<p>Next reduce SAT to 3SAT.  (That&#8217;s a simple reduction, as pointed out in Cook&#8217;s original paper.)</p>
<p>Finally reduce 3SAT to coloring.  (That&#8217;s a standard gadget construction&#8212;it&#8217;s even covered in my GITCS notes, linked to on the sidebar of this blog.)</p>
<p>For more read Garey &#038; Johnson, or google for lecture notes about NP-completeness until you find ones that you like.</p>
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		<title>By: Scott</title>
		<link>http://scottaaronson.com/blog/?p=416#comment-36192</link>
		<author>Scott</author>
		<pubDate>Wed, 19 Aug 2009 15:33:49 +0000</pubDate>
		<guid>http://scottaaronson.com/blog/?p=416#comment-36192</guid>
		<description>Peter Morgan (#181):

&lt;i&gt;So Scott, any opinion on this?&lt;/i&gt;

Sorry, I don't like questions that require reading the questioner's paper even to understand what's being asked. :-)

(Specifically, I don't understand what a "random field" is in your context---is it possible to give a completely discrete explanation, involving only bits and qubits?)</description>
		<content:encoded><![CDATA[<p>Peter Morgan (#181):</p>
<p><i>So Scott, any opinion on this?</i></p>
<p>Sorry, I don&#8217;t like questions that require reading the questioner&#8217;s paper even to understand what&#8217;s being asked. <img src='http://scottaaronson.com/blog/wp-includes/images/smilies/icon_smile.gif' alt=':-)' class='wp-smiley' /> </p>
<p>(Specifically, I don&#8217;t understand what a &#8220;random field&#8221; is in your context&#8212;is it possible to give a completely discrete explanation, involving only bits and qubits?)</p>
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		<title>By: Scott</title>
		<link>http://scottaaronson.com/blog/?p=416#comment-36190</link>
		<author>Scott</author>
		<pubDate>Wed, 19 Aug 2009 15:28:37 +0000</pubDate>
		<guid>http://scottaaronson.com/blog/?p=416#comment-36190</guid>
		<description>harrison (#190):

&lt;i&gt;Can you extend Terry Tao’s wonderful expository relativization metaphor to a wonderful expository metaphor for algebrization?&lt;/i&gt;

I'm a huge fan of Tao's blog, but to be honest, this particular metaphor seems to take something simple and make it complicated.  If it works for you, great---but I'm probably not the right person to extend it to algebrization.</description>
		<content:encoded><![CDATA[<p>harrison (#190):</p>
<p><i>Can you extend Terry Tao’s wonderful expository relativization metaphor to a wonderful expository metaphor for algebrization?</i></p>
<p>I&#8217;m a huge fan of Tao&#8217;s blog, but to be honest, this particular metaphor seems to take something simple and make it complicated.  If it works for you, great&#8212;but I&#8217;m probably not the right person to extend it to algebrization.</p>
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		<title>By: Scott</title>
		<link>http://scottaaronson.com/blog/?p=416#comment-36189</link>
		<author>Scott</author>
		<pubDate>Wed, 19 Aug 2009 15:25:25 +0000</pubDate>
		<guid>http://scottaaronson.com/blog/?p=416#comment-36189</guid>
		<description>Oleg (#194): There's a huge body of recent work on the computational complexity of finding market equilibria---see especially the &lt;a href="http://www.cs.yale.edu/homes/jf/ppad.pdf" rel="nofollow"&gt;breakthrough result&lt;/a&gt; of Daskalakis, Goldberg, and Papadimitriou (and followup work by others) on the PPAD-completeness of computing a Nash equilibrium.</description>
		<content:encoded><![CDATA[<p>Oleg (#194): There&#8217;s a huge body of recent work on the computational complexity of finding market equilibria&#8212;see especially the <a href="http://www.cs.yale.edu/homes/jf/ppad.pdf" rel="nofollow">breakthrough result</a> of Daskalakis, Goldberg, and Papadimitriou (and followup work by others) on the PPAD-completeness of computing a Nash equilibrium.</p>
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		<title>By: Scott</title>
		<link>http://scottaaronson.com/blog/?p=416#comment-36188</link>
		<author>Scott</author>
		<pubDate>Wed, 19 Aug 2009 15:21:42 +0000</pubDate>
		<guid>http://scottaaronson.com/blog/?p=416#comment-36188</guid>
		<description>Ali (#192):

&lt;i&gt;In particular, do you personally think that it is possible to teach oneself and do something without interacting with the bright minds (which I have been doing)?&lt;/i&gt;

Sure, but interacting with "the bright minds" helps, so you should seek them out whenever feasible.</description>
		<content:encoded><![CDATA[<p>Ali (#192):</p>
<p><i>In particular, do you personally think that it is possible to teach oneself and do something without interacting with the bright minds (which I have been doing)?</i></p>
<p>Sure, but interacting with &#8220;the bright minds&#8221; helps, so you should seek them out whenever feasible.</p>
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		<title>By: Scott</title>
		<link>http://scottaaronson.com/blog/?p=416#comment-36186</link>
		<author>Scott</author>
		<pubDate>Wed, 19 Aug 2009 15:19:02 +0000</pubDate>
		<guid>http://scottaaronson.com/blog/?p=416#comment-36186</guid>
		<description>Lew: You can compute arbitrarily good &lt;i&gt;upper and lower bounds&lt;/i&gt; on a computable real number, not just approximations to it.  So given two computable real numbers a&#60;b, you can keep computing better upper bounds on a and better lower bounds on b until you've proved that a&#60;b.</description>
		<content:encoded><![CDATA[<p>Lew: You can compute arbitrarily good <i>upper and lower bounds</i> on a computable real number, not just approximations to it.  So given two computable real numbers a&lt;b, you can keep computing better upper bounds on a and better lower bounds on b until you&#8217;ve proved that a&lt;b.</p>
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