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	<updated>2026-06-19T09:41:54Z</updated>
	<subtitle>User contributions</subtitle>
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	<entry>
		<id>https://drorbn.net/index.php?title=File:07-401_hm9.pdf&amp;diff=4745</id>
		<title>File:07-401 hm9.pdf</title>
		<link rel="alternate" type="text/html" href="https://drorbn.net/index.php?title=File:07-401_hm9.pdf&amp;diff=4745"/>
		<updated>2007-04-18T14:07:40Z</updated>

		<summary type="html">&lt;p&gt;Sm: &lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;&lt;/div&gt;</summary>
		<author><name>Sm</name></author>
	</entry>
	<entry>
		<id>https://drorbn.net/index.php?title=07-401_Solutions&amp;diff=4744</id>
		<title>07-401 Solutions</title>
		<link rel="alternate" type="text/html" href="https://drorbn.net/index.php?title=07-401_Solutions&amp;diff=4744"/>
		<updated>2007-04-18T14:07:21Z</updated>

		<summary type="html">&lt;p&gt;Sm: &lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;[[Image:07-401 hm9.pdf]]&lt;/div&gt;</summary>
		<author><name>Sm</name></author>
	</entry>
	<entry>
		<id>https://drorbn.net/index.php?title=07-401_Solutions&amp;diff=4743</id>
		<title>07-401 Solutions</title>
		<link rel="alternate" type="text/html" href="https://drorbn.net/index.php?title=07-401_Solutions&amp;diff=4743"/>
		<updated>2007-04-18T14:06:48Z</updated>

		<summary type="html">&lt;p&gt;Sm: &lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;&lt;/div&gt;</summary>
		<author><name>Sm</name></author>
	</entry>
	<entry>
		<id>https://drorbn.net/index.php?title=07-401/Homework_Assignment_9&amp;diff=4742</id>
		<title>07-401/Homework Assignment 9</title>
		<link rel="alternate" type="text/html" href="https://drorbn.net/index.php?title=07-401/Homework_Assignment_9&amp;diff=4742"/>
		<updated>2007-04-18T14:06:36Z</updated>

		<summary type="html">&lt;p&gt;Sm: &lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{{07-401/Navigation}}&lt;br /&gt;
&lt;br /&gt;
===Reading===&lt;br /&gt;
Read chapter 32 of Gallian&#039;s book three times:&lt;br /&gt;
* First time as if you were reading a novel - quickly and without too much attention to detail, just to learn what the main keywords and concepts and goals are.&lt;br /&gt;
* Second time like you were studying for an exam on the subject - slowly and not skipping anything, verifying every little detail.&lt;br /&gt;
* And then a third time, again at a quicker pace, to remind yourself of the bigger picture all those little details are there to paint.&lt;br /&gt;
&lt;br /&gt;
===Doing===&lt;br /&gt;
Solve problems 22#, 23, 24#, 25, 26# and 27# in Chapter 32 of Gallian&#039;s book but submit only the solutions of the problems marked with a sharp (#).&lt;br /&gt;
&lt;br /&gt;
===Due Date===&lt;br /&gt;
This assignment is due in class on Wednesday April 4, 2007.&lt;br /&gt;
&lt;br /&gt;
[[07-401 Solutions|Solutions]]&lt;br /&gt;
&lt;br /&gt;
===Just for Fun===&lt;br /&gt;
&lt;br /&gt;
# Explain how the group &amp;lt;math&amp;gt;O(3&amp;lt;/math&amp;gt;) of rigid rotations of &amp;lt;math&amp;gt;{\mathbb R}^3&amp;lt;/math&amp;gt; can be identified with the subgroup &amp;lt;math&amp;gt;\{A\in M_{3\times 3}({\mathbb R}):\, A^TA=I\}&amp;lt;/math&amp;gt; of the group of invertible &amp;lt;math&amp;gt;3\times 3&amp;lt;/math&amp;gt; matrices.&lt;br /&gt;
# Prove that &amp;lt;math&amp;gt;O(3)&amp;lt;/math&amp;gt; is not solvable (though note that the similarly-defined group &amp;lt;math&amp;gt;O(2)&amp;lt;/math&amp;gt; is solvable).&lt;/div&gt;</summary>
		<author><name>Sm</name></author>
	</entry>
	<entry>
		<id>https://drorbn.net/index.php?title=07-401/Homework_Assignment_9&amp;diff=4741</id>
		<title>07-401/Homework Assignment 9</title>
		<link rel="alternate" type="text/html" href="https://drorbn.net/index.php?title=07-401/Homework_Assignment_9&amp;diff=4741"/>
		<updated>2007-04-18T14:06:28Z</updated>

		<summary type="html">&lt;p&gt;Sm: &lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{{07-401/Navigation}}&lt;br /&gt;
&lt;br /&gt;
===Reading===&lt;br /&gt;
Read chapter 32 of Gallian&#039;s book three times:&lt;br /&gt;
* First time as if you were reading a novel - quickly and without too much attention to detail, just to learn what the main keywords and concepts and goals are.&lt;br /&gt;
* Second time like you were studying for an exam on the subject - slowly and not skipping anything, verifying every little detail.&lt;br /&gt;
* And then a third time, again at a quicker pace, to remind yourself of the bigger picture all those little details are there to paint.&lt;br /&gt;
&lt;br /&gt;
===Doing===&lt;br /&gt;
Solve problems 22#, 23, 24#, 25, 26# and 27# in Chapter 32 of Gallian&#039;s book but submit only the solutions of the problems marked with a sharp (#).&lt;br /&gt;
&lt;br /&gt;
===Due Date===&lt;br /&gt;
This assignment is due in class on Wednesday April 4, 2007.&lt;br /&gt;
&lt;br /&gt;
&lt;br /&gt;
&lt;br /&gt;
===Just for Fun===&lt;br /&gt;
&lt;br /&gt;
# Explain how the group &amp;lt;math&amp;gt;O(3&amp;lt;/math&amp;gt;) of rigid rotations of &amp;lt;math&amp;gt;{\mathbb R}^3&amp;lt;/math&amp;gt; can be identified with the subgroup &amp;lt;math&amp;gt;\{A\in M_{3\times 3}({\mathbb R}):\, A^TA=I\}&amp;lt;/math&amp;gt; of the group of invertible &amp;lt;math&amp;gt;3\times 3&amp;lt;/math&amp;gt; matrices.&lt;br /&gt;
# Prove that &amp;lt;math&amp;gt;O(3)&amp;lt;/math&amp;gt; is not solvable (though note that the similarly-defined group &amp;lt;math&amp;gt;O(2)&amp;lt;/math&amp;gt; is solvable).&lt;/div&gt;</summary>
		<author><name>Sm</name></author>
	</entry>
	<entry>
		<id>https://drorbn.net/index.php?title=Template:07-401/Navigation&amp;diff=4637</id>
		<title>Template:07-401/Navigation</title>
		<link rel="alternate" type="text/html" href="https://drorbn.net/index.php?title=Template:07-401/Navigation&amp;diff=4637"/>
		<updated>2007-04-07T15:34:50Z</updated>

		<summary type="html">&lt;p&gt;Sm: &lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{| cellpadding=&amp;quot;0&amp;quot; cellspacing=&amp;quot;0&amp;quot; style=&amp;quot;clear: right; float: right&amp;quot;&lt;br /&gt;
|- align=right&lt;br /&gt;
|&amp;lt;div class=&amp;quot;NavFrame&amp;quot;&amp;gt;&amp;lt;div class=&amp;quot;NavHead&amp;quot;&amp;gt;[[07-401]]/[[Template:07-401/Navigation|Navigation Panel]]&amp;amp;nbsp;&amp;amp;nbsp;&amp;lt;/div&amp;gt;&lt;br /&gt;
&amp;lt;div class=&amp;quot;NavContent&amp;quot;&amp;gt;&lt;br /&gt;
{| border=&amp;quot;1px&amp;quot; cellpadding=&amp;quot;1&amp;quot; cellspacing=&amp;quot;0&amp;quot; width=&amp;quot;220&amp;quot; style=&amp;quot;margin: 0 0 1em 0.5em; font-size: small&amp;quot;&lt;br /&gt;
|- align=center&lt;br /&gt;
!#&lt;br /&gt;
!Week of...&lt;br /&gt;
!Links&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|1&lt;br /&gt;
|Jan 10&lt;br /&gt;
|[[07-401/About This Class|About]], [[07-401/Class Notes for January 10|Notes]], [[07-401/Homework Assignment 1|HW1]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|2&lt;br /&gt;
|Jan 17&lt;br /&gt;
|[[07-401/Homework Assignment 2|HW2]], [[07-401/Class Notes for January 17|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|3&lt;br /&gt;
|Jan 24&lt;br /&gt;
|[[07-401/Homework Assignment 3|HW3]], [[07-401/Class Photo|Photo]], [[07-401/Class Notes for January 24|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|4&lt;br /&gt;
|Jan 31&lt;br /&gt;
|[[07-401/Homework Assignment 4|HW4]], [[07-401/Class Notes for January 31|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|5&lt;br /&gt;
|Feb 7&lt;br /&gt;
|[[07-401/Homework Assignment 5|HW5]], [[07-401/Class Notes for February 7|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|6&lt;br /&gt;
|Feb 14&lt;br /&gt;
|[[07-401/On the Term Test|On TT]], [[07-401/Class Notes for February 14|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|R&lt;br /&gt;
|Feb 21&lt;br /&gt;
|Reading week&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|7&lt;br /&gt;
|Feb 28&lt;br /&gt;
|[[07-401/Term Test|Term Test]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|8&lt;br /&gt;
|Mar 7&lt;br /&gt;
|[[07-401/Homework Assignment 6|HW6]], [[07-401/Class Notes for March 7|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|9&lt;br /&gt;
|Mar 14&lt;br /&gt;
|[[07-401/Homework Assignment 7|HW7]], [[07-401/Class Notes for March 14|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|10&lt;br /&gt;
|Mar 21&lt;br /&gt;
|[[07-401/Homework Assignment 8|HW8]], [[07-401/G&amp;amp;M Article|E8]], [[07-401/Class Notes for March 21|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|11&lt;br /&gt;
|Mar 28&lt;br /&gt;
|[[07-401/Homework Assignment 9|HW9]], [[07-401/Class Notes for March 28|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|12&lt;br /&gt;
|Apr 4&lt;br /&gt;
|[[07-401/Homework Assignment 10 (and last!)|HW10]], [[07-401/Class Notes for April 4|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|13&lt;br /&gt;
|Apr 11&lt;br /&gt;
|[[07-401/Class Notes for April 11|Notes]], [[07-401/Class Evaluation|Eval]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|S&lt;br /&gt;
|Apr 16-20&lt;br /&gt;
|Study Period&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|F&lt;br /&gt;
|Apr 24&lt;br /&gt;
|[[07-401/The Final Exam|Final]]&lt;br /&gt;
|-&lt;br /&gt;
|colspan=3 align=center|[[Image:07-401 Class Photo.jpg|180px]]&amp;lt;br&amp;gt;[[07-401/Class Photo|Add your name / see who&#039;s in!]]&lt;br /&gt;
|-&lt;br /&gt;
|colspan=3 align=center|[[07-401/Register of Good Deeds|Register of Good Deeds]]&lt;br /&gt;
|}&lt;br /&gt;
&amp;lt;/div&amp;gt;&amp;lt;/div&amp;gt;&lt;br /&gt;
|}&lt;br /&gt;
&amp;lt;!-- &amp;lt;div align=center&amp;gt;Announcements go here.&amp;lt;/div&amp;gt; --&amp;gt;&lt;/div&gt;</summary>
		<author><name>Sm</name></author>
	</entry>
	<entry>
		<id>https://drorbn.net/index.php?title=Template:07-401/Navigation&amp;diff=4633</id>
		<title>Template:07-401/Navigation</title>
		<link rel="alternate" type="text/html" href="https://drorbn.net/index.php?title=Template:07-401/Navigation&amp;diff=4633"/>
		<updated>2007-04-07T15:25:31Z</updated>

		<summary type="html">&lt;p&gt;Sm: &lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{| cellpadding=&amp;quot;0&amp;quot; cellspacing=&amp;quot;0&amp;quot; style=&amp;quot;clear: right; float: right&amp;quot;&lt;br /&gt;
|- align=right&lt;br /&gt;
|&amp;lt;div class=&amp;quot;NavFrame&amp;quot;&amp;gt;&amp;lt;div class=&amp;quot;NavHead&amp;quot;&amp;gt;[[07-401]]/[[Template:07-401/Navigation|Navigation Panel]]&amp;amp;nbsp;&amp;amp;nbsp;&amp;lt;/div&amp;gt;&lt;br /&gt;
&amp;lt;div class=&amp;quot;NavContent&amp;quot;&amp;gt;&lt;br /&gt;
{| border=&amp;quot;1px&amp;quot; cellpadding=&amp;quot;1&amp;quot; cellspacing=&amp;quot;0&amp;quot; width=&amp;quot;220&amp;quot; style=&amp;quot;margin: 0 0 1em 0.5em; font-size: small&amp;quot;&lt;br /&gt;
|- align=center&lt;br /&gt;
!#&lt;br /&gt;
!Week of...&lt;br /&gt;
!Links&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|1&lt;br /&gt;
|Jan 10&lt;br /&gt;
|[[07-401/About This Class|About]], [[07-401/Class Notes for January 10|Notes]], [[07-401/Homework Assignment 1|HW1]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|2&lt;br /&gt;
|Jan 17&lt;br /&gt;
|[[07-401/Homework Assignment 2|HW2]], [[07-401/Class Notes for January 17|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|3&lt;br /&gt;
|Jan 24&lt;br /&gt;
|[[07-401/Homework Assignment 3|HW3]], [[07-401/Class Photo|Photo]], [[07-401/Class Notes for January 24|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|4&lt;br /&gt;
|Jan 31&lt;br /&gt;
|[[07-401/Homework Assignment 4|HW4]], [[07-401/Class Notes for January 31|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|5&lt;br /&gt;
|Feb 7&lt;br /&gt;
|[[07-401/Homework Assignment 5|HW5]], [[07-401/Class Notes for February 7|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|6&lt;br /&gt;
|Feb 14&lt;br /&gt;
|[[07-401/On the Term Test|On TT]], [[07-401/Class Notes for February 14|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|R&lt;br /&gt;
|Feb 21&lt;br /&gt;
|Reading week&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|7&lt;br /&gt;
|Feb 28&lt;br /&gt;
|[[07-401/Term Test|Term Test]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|8&lt;br /&gt;
|Mar 7&lt;br /&gt;
|[[07-401/Homework Assignment 6|HW6]], [[07-401/Class Notes for March 7|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|9&lt;br /&gt;
|Mar 14&lt;br /&gt;
|[[07-401/Homework Assignment 7|HW7]], [[07-401/Class Notes for March 14|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|10&lt;br /&gt;
|Mar 21&lt;br /&gt;
|[[07-401/Homework Assignment 8|HW8]], [[07-401/G&amp;amp;M Article|E8]], [[07-401/Class Notes for March 21|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|11&lt;br /&gt;
|Mar 28&lt;br /&gt;
|[[07-401/Homework Assignment 9|HW9]], [[07-401/Class Notes for March 28|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|12&lt;br /&gt;
|Apr 4&lt;br /&gt;
|[[07-401/Homework Assignment 10 (and last!)|HW10]], [[07-401/Class Notes for April 4|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|13&lt;br /&gt;
|Apr 11&lt;br /&gt;
|[[07-401/Class Notes for April 11|Notes]], [[07-401/Class Evaluation|Eval]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|S&lt;br /&gt;
|Apr 16-20&lt;br /&gt;
|Study Period&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|F&lt;br /&gt;
|Apr 24&lt;br /&gt;
|[[07-401/The Final Exam|Final]], [[07-401/Book Review|Review Notes]]&lt;br /&gt;
|-&lt;br /&gt;
|colspan=3 align=center|[[Image:07-401 Class Photo.jpg|180px]]&amp;lt;br&amp;gt;[[07-401/Class Photo|Add your name / see who&#039;s in!]]&lt;br /&gt;
|-&lt;br /&gt;
|colspan=3 align=center|[[07-401/Register of Good Deeds|Register of Good Deeds]]&lt;br /&gt;
|}&lt;br /&gt;
&amp;lt;/div&amp;gt;&amp;lt;/div&amp;gt;&lt;br /&gt;
|}&lt;br /&gt;
&amp;lt;!-- &amp;lt;div align=center&amp;gt;Announcements go here.&amp;lt;/div&amp;gt; --&amp;gt;&lt;/div&gt;</summary>
		<author><name>Sm</name></author>
	</entry>
	<entry>
		<id>https://drorbn.net/index.php?title=07-401/G%26M_Article&amp;diff=4504</id>
		<title>07-401/G&amp;M Article</title>
		<link rel="alternate" type="text/html" href="https://drorbn.net/index.php?title=07-401/G%26M_Article&amp;diff=4504"/>
		<updated>2007-03-21T21:22:31Z</updated>

		<summary type="html">&lt;p&gt;Sm: &lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{{07-401/Navigation}}&lt;br /&gt;
&lt;br /&gt;
I found this today on the Globe and Mail newspaper website. &lt;br /&gt;
Thought it might interest some of you.&lt;br /&gt;
Here is the link to the article:&lt;br /&gt;
http://www.theglobeandmail.com/servlet/story/RTGAM.20070320.wmathpuz0320/BNStory/Science/home&lt;/div&gt;</summary>
		<author><name>Sm</name></author>
	</entry>
	<entry>
		<id>https://drorbn.net/index.php?title=07-401/G%26M_Article&amp;diff=4496</id>
		<title>07-401/G&amp;M Article</title>
		<link rel="alternate" type="text/html" href="https://drorbn.net/index.php?title=07-401/G%26M_Article&amp;diff=4496"/>
		<updated>2007-03-21T15:23:10Z</updated>

		<summary type="html">&lt;p&gt;Sm: &lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;I found this today on the Globe and Mail newspaper website. &lt;br /&gt;
Thought it might interest some of you.&lt;br /&gt;
&lt;br /&gt;
-----------------------------------&lt;br /&gt;
&#039;&#039;&#039;120-year-old math puzzle solved&#039;&#039;&#039;&lt;br /&gt;
Associated Press&lt;br /&gt;
&lt;br /&gt;
PALO ALTO, Calif. — An international team of mathematicians has cracked a 120-year-old puzzle that researchers say is so complicated its handwritten solution would cover the island of Manhattan.&lt;br /&gt;
&lt;br /&gt;
The 18-member group of mathematicians and computer scientists was convened by the American Institute of Mathematics in Palo Alto to map a theoretical object known as the “Lie group E8.”&lt;br /&gt;
&lt;br /&gt;
Lie (pronounced Lee) groups were invented by 19th-century Norwegian mathematician Sophus Lie in his study of symmetrical objects, especially spheres, and differential calculus.&lt;br /&gt;
&lt;br /&gt;
The E8 group, which dates to 1887, is the most complicated Lie group, with 248 dimensions, and was long considered impossible to solve.&lt;br /&gt;
&lt;br /&gt;
“To say what precisely it is is something even many mathematicians can&#039;t understand,” said Jeffrey Adams, the project&#039;s leader and a math professor at the University of Maryland.&lt;br /&gt;
&lt;br /&gt;
The problem&#039;s proof, announced at the Massachusetts Institute of Technology, took the researchers four years to find. It involves about 60 times as much data as the Human Genome Project.&lt;br /&gt;
&lt;br /&gt;
When stored in highly compressed form on a computer hard drive, the solution takes up as much space as 45 days of continuous music in MP3 format.&lt;br /&gt;
&lt;br /&gt;
“It&#039;s like a Mount Everest of mathematical structures they&#039;ve climbed now,” said Brian Conrey, director of the institute.&lt;br /&gt;
&lt;br /&gt;
The calculation does not have any obvious practical applications but could help advance theoretical physics and geometry, researchers said.&lt;/div&gt;</summary>
		<author><name>Sm</name></author>
	</entry>
	<entry>
		<id>https://drorbn.net/index.php?title=Template:07-401/Navigation&amp;diff=4495</id>
		<title>Template:07-401/Navigation</title>
		<link rel="alternate" type="text/html" href="https://drorbn.net/index.php?title=Template:07-401/Navigation&amp;diff=4495"/>
		<updated>2007-03-21T15:19:46Z</updated>

		<summary type="html">&lt;p&gt;Sm: &lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{| cellpadding=&amp;quot;0&amp;quot; cellspacing=&amp;quot;0&amp;quot; style=&amp;quot;clear: right; float: right&amp;quot;&lt;br /&gt;
|- align=right&lt;br /&gt;
|&amp;lt;div class=&amp;quot;NavFrame&amp;quot;&amp;gt;&amp;lt;div class=&amp;quot;NavHead&amp;quot;&amp;gt;[[07-401]]/[[Template:07-401/Navigation|Navigation Panel]]&amp;amp;nbsp;&amp;amp;nbsp;&amp;lt;/div&amp;gt;&lt;br /&gt;
&amp;lt;div class=&amp;quot;NavContent&amp;quot;&amp;gt;&lt;br /&gt;
{| border=&amp;quot;1px&amp;quot; cellpadding=&amp;quot;1&amp;quot; cellspacing=&amp;quot;0&amp;quot; width=&amp;quot;220&amp;quot; style=&amp;quot;margin: 0 0 1em 0.5em; font-size: small&amp;quot;&lt;br /&gt;
|- align=center&lt;br /&gt;
!#&lt;br /&gt;
!Week of...&lt;br /&gt;
!Links&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|1&lt;br /&gt;
|Jan 10&lt;br /&gt;
|[[07-401/About This Class|About]], [[07-401/Class Notes for January 10|Notes]], [[07-401/Homework Assignment 1|HW1]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|2&lt;br /&gt;
|Jan 17&lt;br /&gt;
|[[07-401/Homework Assignment 2|HW2]], [[07-401/Class Notes for January 17|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|3&lt;br /&gt;
|Jan 24&lt;br /&gt;
|[[07-401/Homework Assignment 3|HW3]], [[07-401/Class Photo|Photo]], [[07-401/Class Notes for January 24|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|4&lt;br /&gt;
|Jan 31&lt;br /&gt;
|[[07-401/Homework Assignment 4|HW4]], [[07-401/Class Notes for January 31|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|5&lt;br /&gt;
|Feb 7&lt;br /&gt;
|[[07-401/Homework Assignment 5|HW5]], [[07-401/Class Notes for February 7|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|6&lt;br /&gt;
|Feb 14&lt;br /&gt;
|[[07-401/On the Term Test|On TT]], [[07-401/Class Notes for February 14|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|R&lt;br /&gt;
|Feb 21&lt;br /&gt;
|Reading week&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|7&lt;br /&gt;
|Feb 28&lt;br /&gt;
|[[07-401/Term Test|Term Test]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|8&lt;br /&gt;
|Mar 7&lt;br /&gt;
|[[07-401/Homework Assignment 6|HW6]], [[07-401/Class Notes for March 7|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|9&lt;br /&gt;
|Mar 14&lt;br /&gt;
|[[07-401/Homework Assignment 7|HW7]], [[07-401/Class Notes for March 14|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|10&lt;br /&gt;
|Mar 21&lt;br /&gt;
|[[07-401/Homework Assignment 8|HW8]], [[07-401/G&amp;amp;M Article|E8]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|11&lt;br /&gt;
|Mar 28&lt;br /&gt;
|HW9&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|12&lt;br /&gt;
|Apr 4&lt;br /&gt;
|HW10&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|13&lt;br /&gt;
|Apr 11&lt;br /&gt;
|[[07-401/Class Evaluation|Eval]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|S&lt;br /&gt;
|Apr 16-20&lt;br /&gt;
|Study Period&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|F&lt;br /&gt;
|Apr 24&lt;br /&gt;
|[[07-401/The Final Exam|Final]]&lt;br /&gt;
|-&lt;br /&gt;
|colspan=3 align=center|[[Image:07-401 Class Photo.jpg|180px]]&amp;lt;br&amp;gt;[[07-401/Class Photo|Add your name / see who&#039;s in!]]&lt;br /&gt;
|-&lt;br /&gt;
|colspan=3 align=center|[[07-401/Register of Good Deeds|Register of Good Deeds]]&lt;br /&gt;
|}&lt;br /&gt;
&amp;lt;/div&amp;gt;&amp;lt;/div&amp;gt;&lt;br /&gt;
|}&lt;br /&gt;
&amp;lt;!-- &amp;lt;div align=center&amp;gt;Announcements go here.&amp;lt;/div&amp;gt; --&amp;gt;&lt;/div&gt;</summary>
		<author><name>Sm</name></author>
	</entry>
	<entry>
		<id>https://drorbn.net/index.php?title=07-401/Notes&amp;diff=4364</id>
		<title>07-401/Notes</title>
		<link rel="alternate" type="text/html" href="https://drorbn.net/index.php?title=07-401/Notes&amp;diff=4364"/>
		<updated>2007-03-08T05:08:25Z</updated>

		<summary type="html">&lt;p&gt;Sm: /* Page 1 */&lt;/p&gt;
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		<author><name>Sm</name></author>
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	<entry>
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		<updated>2007-03-08T05:07:03Z</updated>

		<summary type="html">&lt;p&gt;Sm: &lt;/p&gt;
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		<updated>2007-03-08T05:06:36Z</updated>

		<summary type="html">&lt;p&gt;Sm: &lt;/p&gt;
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		<author><name>Sm</name></author>
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		<title>File:07-401 page7.jpg</title>
		<link rel="alternate" type="text/html" href="https://drorbn.net/index.php?title=File:07-401_page7.jpg&amp;diff=4361"/>
		<updated>2007-03-08T05:06:19Z</updated>

		<summary type="html">&lt;p&gt;Sm: &lt;/p&gt;
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		<author><name>Sm</name></author>
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		<updated>2007-03-08T05:05:53Z</updated>

		<summary type="html">&lt;p&gt;Sm: &lt;/p&gt;
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		<updated>2007-03-08T05:05:25Z</updated>

		<summary type="html">&lt;p&gt;Sm: &lt;/p&gt;
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		<updated>2007-03-08T05:04:54Z</updated>

		<summary type="html">&lt;p&gt;Sm: &lt;/p&gt;
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		<author><name>Sm</name></author>
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		<updated>2007-03-08T05:04:22Z</updated>

		<summary type="html">&lt;p&gt;Sm: &lt;/p&gt;
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		<author><name>Sm</name></author>
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		<title>File:07-401 page2.jpg</title>
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		<updated>2007-03-08T05:03:57Z</updated>

		<summary type="html">&lt;p&gt;Sm: &lt;/p&gt;
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		<author><name>Sm</name></author>
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	<entry>
		<id>https://drorbn.net/index.php?title=07-401/Notes&amp;diff=4355</id>
		<title>07-401/Notes</title>
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		<updated>2007-03-08T05:03:41Z</updated>

		<summary type="html">&lt;p&gt;Sm: /* Page 1 */&lt;/p&gt;
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[[Image:07-401 page9.jpg]]&lt;/div&gt;</summary>
		<author><name>Sm</name></author>
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	<entry>
		<id>https://drorbn.net/index.php?title=File:07-401_page1.jpg&amp;diff=4354</id>
		<title>File:07-401 page1.jpg</title>
		<link rel="alternate" type="text/html" href="https://drorbn.net/index.php?title=File:07-401_page1.jpg&amp;diff=4354"/>
		<updated>2007-03-08T05:02:29Z</updated>

		<summary type="html">&lt;p&gt;Sm: &lt;/p&gt;
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		<author><name>Sm</name></author>
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	<entry>
		<id>https://drorbn.net/index.php?title=07-401/Notes&amp;diff=4353</id>
		<title>07-401/Notes</title>
		<link rel="alternate" type="text/html" href="https://drorbn.net/index.php?title=07-401/Notes&amp;diff=4353"/>
		<updated>2007-03-08T05:02:13Z</updated>

		<summary type="html">&lt;p&gt;Sm: /* Page 1 */&lt;/p&gt;
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		<author><name>Sm</name></author>
	</entry>
	<entry>
		<id>https://drorbn.net/index.php?title=07-401/Notes&amp;diff=4352</id>
		<title>07-401/Notes</title>
		<link rel="alternate" type="text/html" href="https://drorbn.net/index.php?title=07-401/Notes&amp;diff=4352"/>
		<updated>2007-03-08T04:57:23Z</updated>

		<summary type="html">&lt;p&gt;Sm: /* Page 1 */&lt;/p&gt;
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		<author><name>Sm</name></author>
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	<entry>
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		<title>07-401/Notes</title>
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		<updated>2007-03-08T03:20:47Z</updated>

		<summary type="html">&lt;p&gt;Sm: /* Page 1 */&lt;/p&gt;
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[[Image:07-401_lecture_wk8.tif]]&lt;/div&gt;</summary>
		<author><name>Sm</name></author>
	</entry>
	<entry>
		<id>https://drorbn.net/index.php?title=07-401/Notes&amp;diff=4338</id>
		<title>07-401/Notes</title>
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		<updated>2007-03-08T03:18:00Z</updated>

		<summary type="html">&lt;p&gt;Sm: &lt;/p&gt;
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		<author><name>Sm</name></author>
	</entry>
	<entry>
		<id>https://drorbn.net/index.php?title=07-401/Class_Notes_for_March_7&amp;diff=4336</id>
		<title>07-401/Class Notes for March 7</title>
		<link rel="alternate" type="text/html" href="https://drorbn.net/index.php?title=07-401/Class_Notes_for_March_7&amp;diff=4336"/>
		<updated>2007-03-08T03:17:37Z</updated>

		<summary type="html">&lt;p&gt;Sm: /* Class Plan */&lt;/p&gt;
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&lt;div&gt;{{07-401/Navigation}}&lt;br /&gt;
&lt;br /&gt;
==Class Plan==&lt;br /&gt;
&lt;br /&gt;
Some discussion of the [[07-401/Term Test|term test]] and [[07-401/Homework Assignment 6|HW6]].&lt;br /&gt;
&lt;br /&gt;
Some discussion of our general plan.&lt;br /&gt;
&lt;br /&gt;
Lecture [[07-401/Notes|notes]]&lt;br /&gt;
&lt;br /&gt;
===Extension Fields===&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Definition.&#039;&#039;&#039; An extension field &amp;lt;math&amp;gt;E&amp;lt;/math&amp;gt; of &amp;lt;math&amp;gt;F&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Theorem.&#039;&#039;&#039; For every non-constant polynomial &amp;lt;math&amp;gt;f&amp;lt;/math&amp;gt; in &amp;lt;math&amp;gt;F[x]&amp;lt;/math&amp;gt; there is an extension &amp;lt;math&amp;gt;E&amp;lt;/math&amp;gt; of &amp;lt;math&amp;gt;F&amp;lt;/math&amp;gt; in which &amp;lt;math&amp;gt;f&amp;lt;/math&amp;gt; has a zero.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Example&#039;&#039;&#039; &amp;lt;math&amp;gt;x^2+1&amp;lt;/math&amp;gt; over &amp;lt;math&amp;gt;{\mathbb R}&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Example&#039;&#039;&#039; &amp;lt;math&amp;gt;x^5+2x^2+2x+2=(x^2+1)(x^3+2x+2)&amp;lt;/math&amp;gt; over &amp;lt;math&amp;gt;{\mathbb Z}/3&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Definition.&#039;&#039;&#039; &amp;lt;math&amp;gt;F(a_1,\ldots,a_n)&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Theorem.&#039;&#039;&#039; If &amp;lt;math&amp;gt;a&amp;lt;/math&amp;gt; is a root of an irreducible polynomial &amp;lt;math&amp;gt;p\in F[x]&amp;lt;/math&amp;gt;, within some extension field &amp;lt;math&amp;gt;E&amp;lt;/math&amp;gt; of &amp;lt;math&amp;gt;F&amp;lt;/math&amp;gt;, then &amp;lt;math&amp;gt;F(a)\cong F[x]/\langle p\rangle&amp;lt;/math&amp;gt;, and &amp;lt;math&amp;gt;\{1,a,a^2,\ldots,a^{n-1}\}&amp;lt;/math&amp;gt; (here &amp;lt;math&amp;gt;n=\deg p&amp;lt;/math&amp;gt;) is a basis for &amp;lt;math&amp;gt;F(a)&amp;lt;/math&amp;gt; over &amp;lt;math&amp;gt;F&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Corollary.&#039;&#039;&#039; In this case, &amp;lt;math&amp;gt;F(a)&amp;lt;/math&amp;gt; depends only on &amp;lt;math&amp;gt;p&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
===Splitting Fields===&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Definition.&#039;&#039;&#039; &amp;lt;math&amp;gt;f\in F[x]&amp;lt;/math&amp;gt; splits in &amp;lt;math&amp;gt;E/F&amp;lt;/math&amp;gt;, a splitting field for &amp;lt;math&amp;gt;f&amp;lt;/math&amp;gt; over &amp;lt;math&amp;gt;F&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Theorem.&#039;&#039;&#039; A splitting field always exists.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Example.&#039;&#039;&#039; &amp;lt;math&amp;gt;x^4-x^2-2=(x^2-2)(x^2+1)&amp;lt;/math&amp;gt; over &amp;lt;math&amp;gt;{\mathbb Q}&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Example.&#039;&#039;&#039; Factor &amp;lt;math&amp;gt;x^2+x+2\in{\mathbb Z}_3[x]&amp;lt;/math&amp;gt; within its splitting field &amp;lt;math&amp;gt;{\mathbb Z}_3[x]/\langle x^2+x+2\rangle&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Theorem.&#039;&#039;&#039; Any two splitting fields for &amp;lt;math&amp;gt;f\in F[x]&amp;lt;/math&amp;gt; over &amp;lt;math&amp;gt;F&amp;lt;/math&amp;gt; are isomorphic.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Lemma 1.&#039;&#039;&#039; If &amp;lt;math&amp;gt;p\in F[x]&amp;lt;/math&amp;gt; irreducible over &amp;lt;math&amp;gt;F&amp;lt;/math&amp;gt;, &amp;lt;math&amp;gt;\phi:F\to F&#039;&amp;lt;/math&amp;gt; an isomorphism, &amp;lt;math&amp;gt;a&amp;lt;/math&amp;gt; a root of &amp;lt;math&amp;gt;p&amp;lt;/math&amp;gt; (in some &amp;lt;math&amp;gt;E/F&amp;lt;/math&amp;gt;), &amp;lt;math&amp;gt;a&#039;&amp;lt;/math&amp;gt; a root of &amp;lt;math&amp;gt;\phi(p)&amp;lt;/math&amp;gt; in some &amp;lt;math&amp;gt;E&#039;/F&#039;&amp;lt;/math&amp;gt;, then &amp;lt;math&amp;gt;F(a)\cong F&#039;(a&#039;)&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Lemma 2.&#039;&#039;&#039; Isomorphisms can be extended to splitting fields.&lt;br /&gt;
&lt;br /&gt;
===Zeros of Irreducible Polynomials===&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Definition.&#039;&#039;&#039; The derivative of a polynomial.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Claim.&#039;&#039;&#039; The derivative operation is linear and satisfies Leibnitz&#039;s law.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Theorem.&#039;&#039;&#039; &amp;lt;math&amp;gt;f\in F[x]&amp;lt;/math&amp;gt; has a multiple zero in some extension field of &amp;lt;math&amp;gt;F&amp;lt;/math&amp;gt; iff &amp;lt;math&amp;gt;f&amp;lt;/math&amp;gt; and &amp;lt;math&amp;gt;f&#039;&amp;lt;/math&amp;gt; have a common factor of positive degree.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Lemma.&#039;&#039;&#039; The property of &amp;quot;being relatively prime&amp;quot; is preserved under extensions.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Theorem.&#039;&#039;&#039; Let &amp;lt;math&amp;gt;f\in F[x]&amp;lt;/math&amp;gt; be irreducible. If &amp;lt;math&amp;gt;\operatorname{char}F=0&amp;lt;/math&amp;gt;, then &amp;lt;math&amp;gt;f&amp;lt;/math&amp;gt; has no multiple zeros in any extension of &amp;lt;math&amp;gt;F&amp;lt;/math&amp;gt;. If &amp;lt;math&amp;gt;\operatorname{char}F=p&amp;gt;0&amp;lt;/math&amp;gt;, then &amp;lt;math&amp;gt;f&amp;lt;/math&amp;gt; has multiple zeros (in some extension) iff it is of the form &amp;lt;math&amp;gt;g(x^p)&amp;lt;/math&amp;gt; for some &amp;lt;math&amp;gt;g\in F[x]&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Definition.&#039;&#039;&#039; A perfect field.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Theorem.&#039;&#039;&#039; A finite field is perfect.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Theorem.&#039;&#039;&#039; An irreducible polynomial over a perfect field has no multiple zeros (in any extension).&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Theorem.&#039;&#039;&#039; Let &amp;lt;math&amp;gt;f\in F[x]&amp;lt;/math&amp;gt; be irreducible and let &amp;lt;math&amp;gt;E&amp;lt;/math&amp;gt; be the splitting field of &amp;lt;math&amp;gt;f&amp;lt;/math&amp;gt; over &amp;lt;math&amp;gt;F&amp;lt;/math&amp;gt;. Then in &amp;lt;math&amp;gt;E&amp;lt;/math&amp;gt; all zeros of &amp;lt;math&amp;gt;f&amp;lt;/math&amp;gt; have the same multiplicity.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Corollary.&#039;&#039;&#039; &amp;lt;math&amp;gt;f&amp;lt;/math&amp;gt; as above must have the form &amp;lt;math&amp;gt;a(x-a_1)^n\cdots(x-a_k)^n&amp;lt;/math&amp;gt; for some &amp;lt;math&amp;gt;a\in F&amp;lt;/math&amp;gt; and &amp;lt;math&amp;gt;a_1,\ldots,a_k\in E&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Example.&#039;&#039;&#039; &amp;lt;math&amp;gt;x^2-t\in{\mathbb Z}_2(t)[x]&amp;lt;/math&amp;gt; is irreducible and has a single zero of multiplicity 2 within its splitting field over &amp;lt;math&amp;gt;{\mathbb Z}_2(t)[x]&amp;lt;/math&amp;gt;.&lt;/div&gt;</summary>
		<author><name>Sm</name></author>
	</entry>
	<entry>
		<id>https://drorbn.net/index.php?title=07-401/Class_Notes_for_March_7&amp;diff=4335</id>
		<title>07-401/Class Notes for March 7</title>
		<link rel="alternate" type="text/html" href="https://drorbn.net/index.php?title=07-401/Class_Notes_for_March_7&amp;diff=4335"/>
		<updated>2007-03-08T03:15:04Z</updated>

		<summary type="html">&lt;p&gt;Sm: /* Class Plan */&lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{{07-401/Navigation}}&lt;br /&gt;
&lt;br /&gt;
==Class Plan==&lt;br /&gt;
&lt;br /&gt;
Some discussion of the [[07-401/Term Test|term test]] and [[07-401/Homework Assignment 6|HW6]].&lt;br /&gt;
&lt;br /&gt;
Some discussion of our general plan.&lt;br /&gt;
&lt;br /&gt;
Lecture notes [[07-401/Notes|notes]]&lt;br /&gt;
&lt;br /&gt;
===Extension Fields===&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Definition.&#039;&#039;&#039; An extension field &amp;lt;math&amp;gt;E&amp;lt;/math&amp;gt; of &amp;lt;math&amp;gt;F&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Theorem.&#039;&#039;&#039; For every non-constant polynomial &amp;lt;math&amp;gt;f&amp;lt;/math&amp;gt; in &amp;lt;math&amp;gt;F[x]&amp;lt;/math&amp;gt; there is an extension &amp;lt;math&amp;gt;E&amp;lt;/math&amp;gt; of &amp;lt;math&amp;gt;F&amp;lt;/math&amp;gt; in which &amp;lt;math&amp;gt;f&amp;lt;/math&amp;gt; has a zero.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Example&#039;&#039;&#039; &amp;lt;math&amp;gt;x^2+1&amp;lt;/math&amp;gt; over &amp;lt;math&amp;gt;{\mathbb R}&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Example&#039;&#039;&#039; &amp;lt;math&amp;gt;x^5+2x^2+2x+2=(x^2+1)(x^3+2x+2)&amp;lt;/math&amp;gt; over &amp;lt;math&amp;gt;{\mathbb Z}/3&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Definition.&#039;&#039;&#039; &amp;lt;math&amp;gt;F(a_1,\ldots,a_n)&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Theorem.&#039;&#039;&#039; If &amp;lt;math&amp;gt;a&amp;lt;/math&amp;gt; is a root of an irreducible polynomial &amp;lt;math&amp;gt;p\in F[x]&amp;lt;/math&amp;gt;, within some extension field &amp;lt;math&amp;gt;E&amp;lt;/math&amp;gt; of &amp;lt;math&amp;gt;F&amp;lt;/math&amp;gt;, then &amp;lt;math&amp;gt;F(a)\cong F[x]/\langle p\rangle&amp;lt;/math&amp;gt;, and &amp;lt;math&amp;gt;\{1,a,a^2,\ldots,a^{n-1}\}&amp;lt;/math&amp;gt; (here &amp;lt;math&amp;gt;n=\deg p&amp;lt;/math&amp;gt;) is a basis for &amp;lt;math&amp;gt;F(a)&amp;lt;/math&amp;gt; over &amp;lt;math&amp;gt;F&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Corollary.&#039;&#039;&#039; In this case, &amp;lt;math&amp;gt;F(a)&amp;lt;/math&amp;gt; depends only on &amp;lt;math&amp;gt;p&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
===Splitting Fields===&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Definition.&#039;&#039;&#039; &amp;lt;math&amp;gt;f\in F[x]&amp;lt;/math&amp;gt; splits in &amp;lt;math&amp;gt;E/F&amp;lt;/math&amp;gt;, a splitting field for &amp;lt;math&amp;gt;f&amp;lt;/math&amp;gt; over &amp;lt;math&amp;gt;F&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Theorem.&#039;&#039;&#039; A splitting field always exists.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Example.&#039;&#039;&#039; &amp;lt;math&amp;gt;x^4-x^2-2=(x^2-2)(x^2+1)&amp;lt;/math&amp;gt; over &amp;lt;math&amp;gt;{\mathbb Q}&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Example.&#039;&#039;&#039; Factor &amp;lt;math&amp;gt;x^2+x+2\in{\mathbb Z}_3[x]&amp;lt;/math&amp;gt; within its splitting field &amp;lt;math&amp;gt;{\mathbb Z}_3[x]/\langle x^2+x+2\rangle&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Theorem.&#039;&#039;&#039; Any two splitting fields for &amp;lt;math&amp;gt;f\in F[x]&amp;lt;/math&amp;gt; over &amp;lt;math&amp;gt;F&amp;lt;/math&amp;gt; are isomorphic.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Lemma 1.&#039;&#039;&#039; If &amp;lt;math&amp;gt;p\in F[x]&amp;lt;/math&amp;gt; irreducible over &amp;lt;math&amp;gt;F&amp;lt;/math&amp;gt;, &amp;lt;math&amp;gt;\phi:F\to F&#039;&amp;lt;/math&amp;gt; an isomorphism, &amp;lt;math&amp;gt;a&amp;lt;/math&amp;gt; a root of &amp;lt;math&amp;gt;p&amp;lt;/math&amp;gt; (in some &amp;lt;math&amp;gt;E/F&amp;lt;/math&amp;gt;), &amp;lt;math&amp;gt;a&#039;&amp;lt;/math&amp;gt; a root of &amp;lt;math&amp;gt;\phi(p)&amp;lt;/math&amp;gt; in some &amp;lt;math&amp;gt;E&#039;/F&#039;&amp;lt;/math&amp;gt;, then &amp;lt;math&amp;gt;F(a)\cong F&#039;(a&#039;)&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Lemma 2.&#039;&#039;&#039; Isomorphisms can be extended to splitting fields.&lt;br /&gt;
&lt;br /&gt;
===Zeros of Irreducible Polynomials===&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Definition.&#039;&#039;&#039; The derivative of a polynomial.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Claim.&#039;&#039;&#039; The derivative operation is linear and satisfies Leibnitz&#039;s law.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Theorem.&#039;&#039;&#039; &amp;lt;math&amp;gt;f\in F[x]&amp;lt;/math&amp;gt; has a multiple zero in some extension field of &amp;lt;math&amp;gt;F&amp;lt;/math&amp;gt; iff &amp;lt;math&amp;gt;f&amp;lt;/math&amp;gt; and &amp;lt;math&amp;gt;f&#039;&amp;lt;/math&amp;gt; have a common factor of positive degree.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Lemma.&#039;&#039;&#039; The property of &amp;quot;being relatively prime&amp;quot; is preserved under extensions.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Theorem.&#039;&#039;&#039; Let &amp;lt;math&amp;gt;f\in F[x]&amp;lt;/math&amp;gt; be irreducible. If &amp;lt;math&amp;gt;\operatorname{char}F=0&amp;lt;/math&amp;gt;, then &amp;lt;math&amp;gt;f&amp;lt;/math&amp;gt; has no multiple zeros in any extension of &amp;lt;math&amp;gt;F&amp;lt;/math&amp;gt;. If &amp;lt;math&amp;gt;\operatorname{char}F=p&amp;gt;0&amp;lt;/math&amp;gt;, then &amp;lt;math&amp;gt;f&amp;lt;/math&amp;gt; has multiple zeros (in some extension) iff it is of the form &amp;lt;math&amp;gt;g(x^p)&amp;lt;/math&amp;gt; for some &amp;lt;math&amp;gt;g\in F[x]&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Definition.&#039;&#039;&#039; A perfect field.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Theorem.&#039;&#039;&#039; A finite field is perfect.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Theorem.&#039;&#039;&#039; An irreducible polynomial over a perfect field has no multiple zeros (in any extension).&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Theorem.&#039;&#039;&#039; Let &amp;lt;math&amp;gt;f\in F[x]&amp;lt;/math&amp;gt; be irreducible and let &amp;lt;math&amp;gt;E&amp;lt;/math&amp;gt; be the splitting field of &amp;lt;math&amp;gt;f&amp;lt;/math&amp;gt; over &amp;lt;math&amp;gt;F&amp;lt;/math&amp;gt;. Then in &amp;lt;math&amp;gt;E&amp;lt;/math&amp;gt; all zeros of &amp;lt;math&amp;gt;f&amp;lt;/math&amp;gt; have the same multiplicity.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Corollary.&#039;&#039;&#039; &amp;lt;math&amp;gt;f&amp;lt;/math&amp;gt; as above must have the form &amp;lt;math&amp;gt;a(x-a_1)^n\cdots(x-a_k)^n&amp;lt;/math&amp;gt; for some &amp;lt;math&amp;gt;a\in F&amp;lt;/math&amp;gt; and &amp;lt;math&amp;gt;a_1,\ldots,a_k\in E&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
&#039;&#039;&#039;Example.&#039;&#039;&#039; &amp;lt;math&amp;gt;x^2-t\in{\mathbb Z}_2(t)[x]&amp;lt;/math&amp;gt; is irreducible and has a single zero of multiplicity 2 within its splitting field over &amp;lt;math&amp;gt;{\mathbb Z}_2(t)[x]&amp;lt;/math&amp;gt;.&lt;/div&gt;</summary>
		<author><name>Sm</name></author>
	</entry>
	<entry>
		<id>https://drorbn.net/index.php?title=07-401/Class_Notes_for_February_14&amp;diff=4005</id>
		<title>07-401/Class Notes for February 14</title>
		<link rel="alternate" type="text/html" href="https://drorbn.net/index.php?title=07-401/Class_Notes_for_February_14&amp;diff=4005"/>
		<updated>2007-02-15T00:09:13Z</updated>

		<summary type="html">&lt;p&gt;Sm: &lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{{07-401/Navigation}}&lt;br /&gt;
&lt;br /&gt;
==Page 1==&lt;br /&gt;
&lt;br /&gt;
[[Image:07-401-Feb14-1.jpg|600px]]&lt;br /&gt;
&lt;br /&gt;
==Page 2==&lt;br /&gt;
&lt;br /&gt;
[[Image:07-401-Feb14-2.jpg|600px]]&lt;/div&gt;</summary>
		<author><name>Sm</name></author>
	</entry>
	<entry>
		<id>https://drorbn.net/index.php?title=Template:07-401/Navigation&amp;diff=4004</id>
		<title>Template:07-401/Navigation</title>
		<link rel="alternate" type="text/html" href="https://drorbn.net/index.php?title=Template:07-401/Navigation&amp;diff=4004"/>
		<updated>2007-02-15T00:07:58Z</updated>

		<summary type="html">&lt;p&gt;Sm: &lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{| cellpadding=&amp;quot;0&amp;quot; cellspacing=&amp;quot;0&amp;quot; style=&amp;quot;clear: right; float: right&amp;quot;&lt;br /&gt;
|- align=right&lt;br /&gt;
|&amp;lt;div class=&amp;quot;NavFrame&amp;quot;&amp;gt;&amp;lt;div class=&amp;quot;NavHead&amp;quot;&amp;gt;[[07-401]]/[[Template:07-401/Navigation|Navigation Panel]]&amp;amp;nbsp;&amp;amp;nbsp;&amp;lt;/div&amp;gt;&lt;br /&gt;
&amp;lt;div class=&amp;quot;NavContent&amp;quot;&amp;gt;&lt;br /&gt;
{| border=&amp;quot;1px&amp;quot; cellpadding=&amp;quot;1&amp;quot; cellspacing=&amp;quot;0&amp;quot; width=&amp;quot;220&amp;quot; style=&amp;quot;margin: 0 0 1em 0.5em; font-size: small&amp;quot;&lt;br /&gt;
|- align=center&lt;br /&gt;
!#&lt;br /&gt;
!Week of...&lt;br /&gt;
!Links&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|1&lt;br /&gt;
|Jan 10&lt;br /&gt;
|[[07-401/About This Class|About]], [[07-401/Class Notes for January 10|Notes]], [[07-401/Homework Assignment 1|HW1]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|2&lt;br /&gt;
|Jan 17&lt;br /&gt;
|[[07-401/Homework Assignment 2|HW2]], [[07-401/Class Notes for January 17|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|3&lt;br /&gt;
|Jan 24&lt;br /&gt;
|[[07-401/Homework Assignment 3|HW3]], [[07-401/Class Photo|Photo]], [[07-401/Class Notes for January 24|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|4&lt;br /&gt;
|Jan 31&lt;br /&gt;
|[[07-401/Homework Assignment 4|HW4]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|5&lt;br /&gt;
|Feb 7&lt;br /&gt;
|[[07-401/Homework Assignment 5|HW5]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|6&lt;br /&gt;
|Feb 14&lt;br /&gt;
|[[07-401/On the Term Test|On TT]], [[07-401/Class Notes for February 14|Notes]]&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|R&lt;br /&gt;
|Feb 21&lt;br /&gt;
|Reading week&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|7&lt;br /&gt;
|Feb 28&lt;br /&gt;
|TT&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|8&lt;br /&gt;
|Mar 7&lt;br /&gt;
|HW6&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|9&lt;br /&gt;
|Mar 14&lt;br /&gt;
|HW7&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|10&lt;br /&gt;
|Mar 21&lt;br /&gt;
|HW8&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|11&lt;br /&gt;
|Mar 28&lt;br /&gt;
|HW9&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|12&lt;br /&gt;
|Apr 4&lt;br /&gt;
|HW10&lt;br /&gt;
|- align=left&lt;br /&gt;
|align=center|13&lt;br /&gt;
|Apr 11&lt;br /&gt;
|&lt;br /&gt;
|-&lt;br /&gt;
|colspan=3 align=center|[[Image:07-401 Class Photo.jpg|180px]]&amp;lt;br&amp;gt;[[07-401/Class Photo|Add your name / see who&#039;s in!]]&lt;br /&gt;
|-&lt;br /&gt;
|colspan=3 align=center|[[07-401/Register of Good Deeds|Register of Good Deeds]]&lt;br /&gt;
|}&lt;br /&gt;
&amp;lt;/div&amp;gt;&amp;lt;/div&amp;gt;&lt;br /&gt;
|}&lt;br /&gt;
&amp;lt;div align=center&amp;gt;Our &amp;lt;font color=red&amp;gt;&#039;&#039;&#039;Term Test&#039;&#039;&#039;&amp;lt;/font&amp;gt; is on February 28 at 6:20PM at &amp;lt;font color=red&amp;gt;&#039;&#039;&#039;Galbraith (GB) 120&#039;&#039;&#039;&amp;lt;/font&amp;gt;. [[07-401/On the Term Test|Read more.]]&amp;lt;/div&amp;gt;&lt;/div&gt;</summary>
		<author><name>Sm</name></author>
	</entry>
	<entry>
		<id>https://drorbn.net/index.php?title=Talk:07-401/About_This_Class&amp;diff=3812</id>
		<title>Talk:07-401/About This Class</title>
		<link rel="alternate" type="text/html" href="https://drorbn.net/index.php?title=Talk:07-401/About_This_Class&amp;diff=3812"/>
		<updated>2007-02-01T01:10:53Z</updated>

		<summary type="html">&lt;p&gt;Sm: &lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;Prof, May you please clarify the date for our midterm. Is it February 28th or March 7th?&lt;br /&gt;
Thanks!!!&lt;/div&gt;</summary>
		<author><name>Sm</name></author>
	</entry>
	<entry>
		<id>https://drorbn.net/index.php?title=07-401/Class_Photo&amp;diff=3711</id>
		<title>07-401/Class Photo</title>
		<link rel="alternate" type="text/html" href="https://drorbn.net/index.php?title=07-401/Class_Photo&amp;diff=3711"/>
		<updated>2007-01-25T23:42:31Z</updated>

		<summary type="html">&lt;p&gt;Sm: /* Who We Are... */&lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{{07-401/Navigation}}&lt;br /&gt;
&lt;br /&gt;
Our class on Janury 24, 2007:&lt;br /&gt;
&lt;br /&gt;
[[Image:07-401 Class Photo.jpg|thumb|centre|500px|Class Photo: click to enlarge]]&lt;br /&gt;
&lt;br /&gt;
Please identify yourself in this photo! There are two ways to do that:&lt;br /&gt;
&lt;br /&gt;
* [[Special:Userlogin|Log in]] to this Wiki and edit this page. Put your name, userid, email address and location in the picture in the alphabetical list below.&lt;br /&gt;
* Send [[User:Drorbn|Dror]] an email message with this information.&lt;br /&gt;
&lt;br /&gt;
The first option is more fun but less private.&lt;br /&gt;
&lt;br /&gt;
===Who We Are...===&lt;br /&gt;
&lt;br /&gt;
{| align=center border=1 &lt;br /&gt;
|-&lt;br /&gt;
!First name&lt;br /&gt;
!Last name &lt;br /&gt;
!UserID &lt;br /&gt;
!Email &lt;br /&gt;
!In the photo &lt;br /&gt;
!Comments&lt;br /&gt;
{{Photo Entry|last=Bar-Natan|first=Dror|userid=Drorbn|email=drorbn@ math.toronto.edu|location=facing everybody, as the photographer|comments=Take this entry as a model and leave it first. Otherwise alphabetize by last name. Feel free to leave some fields blank}}&lt;br /&gt;
{{Photo Entry|last=Castro|first=Caroline|userid=Carrot|email=caroline.castro@utoronto.ca|&lt;br /&gt;
location=the tall person at the very top of the stairs with the grey hat|comments=no comment.}}&lt;br /&gt;
{{Photo Entry|last=Henderson|first=Sean|userid=sean_henderson|email=sean.henderson[at]utoronto.ca|location=front row, far left|comments=no comment.}}&lt;br /&gt;
{{Photo Entry|last=Maniak|first=Sylvia|userid=sm|email=sylvia.maniak[at]gmail.com|location=front row, the blonde wearing a black shirt|comments=no comment.}}&lt;/div&gt;</summary>
		<author><name>Sm</name></author>
	</entry>
	<entry>
		<id>https://drorbn.net/index.php?title=07-401/Class_Photo&amp;diff=3710</id>
		<title>07-401/Class Photo</title>
		<link rel="alternate" type="text/html" href="https://drorbn.net/index.php?title=07-401/Class_Photo&amp;diff=3710"/>
		<updated>2007-01-25T23:40:07Z</updated>

		<summary type="html">&lt;p&gt;Sm: /* Who We Are... */&lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{{07-401/Navigation}}&lt;br /&gt;
&lt;br /&gt;
Our class on Janury 24, 2007:&lt;br /&gt;
&lt;br /&gt;
[[Image:07-401 Class Photo.jpg|thumb|centre|500px|Class Photo: click to enlarge]]&lt;br /&gt;
&lt;br /&gt;
Please identify yourself in this photo! There are two ways to do that:&lt;br /&gt;
&lt;br /&gt;
* [[Special:Userlogin|Log in]] to this Wiki and edit this page. Put your name, userid, email address and location in the picture in the alphabetical list below.&lt;br /&gt;
* Send [[User:Drorbn|Dror]] an email message with this information.&lt;br /&gt;
&lt;br /&gt;
The first option is more fun but less private.&lt;br /&gt;
&lt;br /&gt;
===Who We Are...===&lt;br /&gt;
&lt;br /&gt;
{| align=center border=1 &lt;br /&gt;
|-&lt;br /&gt;
!First name Sylvia&lt;br /&gt;
!Last name Maniak&lt;br /&gt;
!UserID sm&lt;br /&gt;
!Email sylvia.maniak@gmail.com&lt;br /&gt;
!In the photo blonde in the black shirt, first row&lt;br /&gt;
!Comments&lt;br /&gt;
{{Photo Entry|last=Bar-Natan|first=Dror|userid=Drorbn|email=drorbn@ math.toronto.edu|location=facing everybody, as the photographer|comments=Take this entry as a model and leave it first. Otherwise alphabetize by last name. Feel free to leave some fields blank}}&lt;br /&gt;
{{Photo Entry|last=Castro|first=Caroline|userid=Carrot|email=caroline.castro@utoronto.ca|&lt;br /&gt;
location=the tall person at the very top of the stairs with the grey hat|comments=no comment.}}&lt;br /&gt;
{{Photo Entry|last=Henderson|first=Sean|userid=sean_henderson|email=sean.henderson[at]utoronto.ca|location=front row, far left|comments=no comment.}}&lt;/div&gt;</summary>
		<author><name>Sm</name></author>
	</entry>
</feed>