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		<title>Seriously now, where was the Bourbaki wedding?</title>
		<link>https://lievenlebruyn.github.io/neverendingbooks/seriously-now-where-was-the-bourbaki-wedding/</link>
		
		<dc:creator><![CDATA[lieven]]></dc:creator>
		<pubDate>Wed, 25 Nov 2009 11:15:59 +0000</pubDate>
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		<guid isPermaLink="false">http://www.neverendingbooks.org/?p=2569</guid>

					<description><![CDATA[A few days before Halloween, Norbert Dufourcq (who died december 17th 1990&#8230;), sent me a comment, containing lots of useful information, hinting I did get&#8230;]]></description>
										<content:encoded><![CDATA[<p>A few days before Halloween, <a href="http://fr.wikipedia.org/wiki/Norbert_Dufourcq">Norbert Dufourcq</a> (who died december 17th 1990&#8230;), sent me a <a href="https://lievenlebruyn.github.io/neverendingbooks/index.php/where-was-the-bourbaki-wedding.html/comment-page-1#comment-8463">comment</a>, containing lots of useful information, hinting I did get it wrong about the church of the Bourbali wedding in the <a href="https://lievenlebruyn.github.io/neverendingbooks/index.php/where-was-the-bourbaki-wedding.html/">previous post</a>.</p>
<p>Norbert Dufourcq, an organist and student of <a href="http://fr.wikipedia.org/wiki/André_Marchal">Andre Machall</a>, the organist-in-charge at the Saint-Germain-des-Prés church in 1939, the place where <a href="https://lievenlebruyn.github.io/neverendingbooks/index.php/where-was-the-bourbaki-wedding.html/">I speculated</a> the Bourbaki wedding took place, concluded his comment with :</p>
<p><strong>&#8220;P.S. Lieven, you _do_ know about the Schola Cantorum, now, don&#8217;t you?!?&#8221;</strong>.</p>
<p> Euh&#8230; actually &#8230; no, I did not &#8230;</p>
<p><img decoding="async" style="float:right; margin-left:10px;" src="https://lievenlebruyn.github.io/neverendingbooks/DATA2/ScholaCantorum.jpg"><a href="http://en.wikipedia.org/wiki/Schola_Cantorum">La Schola Cantorum</a> is a private music school in Paris. It was founded in 1894 by Charles Bordes, Alexandre Guilmant and Vincent d&#8217;Indy as a counterbalance to the Paris Conservatoire&#8217;s emphasis on opera. Its alumni include many significant figures in 20th century music, such as <a href="http://en.wikipedia.org/wiki/Erik_Satie">Erik Satie</a> and <a href="http://en.wikipedia.org/wiki/Cole_Porter">Cole Porter</a>.</p>
<p><a href="http://www.schola-cantorum.com/">Schola Cantorum</a> is situated 69, rue Saint Jacques, Paris, just around the corner of the <a href="http://www.ens.fr/?lang=fr">Ecole Normal Superieure</a>, home base to the Bourbakis. In fact, closer investigation reveals striking similarities and very close connections between the circle of artists at la Schola and the Bourbaki group.</p>
<p>In december 1934, the exact month the Bourbaki group was formed, a radical reorganisation took place at the Schola, when Nestor Lejeune became the new director. He invited several young musicians, many from the famous Dukas-class, to take up teaching positions at the Schola.</p>
<p>Here&#8217;s a picture of part of the <a href="http://en.wikipedia.org/wiki/File:Classe-dukas.jpg">Dukas class of 1929</a>, several of its members will play a role in the upcoming events :<br />
from left to right next to the piano : Pierre Maillard-Verger, Elsa Barraine, Yvonne Desportes, Tony Aubin, Pierre Revel, Georges Favre, Paul Dukas, René Duclos, Georges Hugon, Maurice Duruflé. Seated on the right : Claude Arrieu, Olivier Messiaen.</p>
<p />
<p><center><br />
<img decoding="async" src="https://lievenlebruyn.github.io/neverendingbooks/DATA2/ClasseDukas.jpg"><br />
</center></p>
<p>The mid-1930s in Paris saw the emergence of two closely-related groups with a membership which overlapped : <a href="http://books.google.com/books?id=UgGBXwpHTe8C&amp;pg=PA142&amp;lpg=PA142&amp;dq=la+spirale+Georges+Migot&amp;source=bl&amp;ots=UgEENf63Am&amp;sig=vU2ac8Lu3Rbtb5zWEDSa7dA9yNY&amp;hl=en&amp;ei=R04ES5qEFs_B-QaLiKXKCg&amp;sa=X&amp;oi=book_result&amp;ct=result&amp;resnum=3&amp;ved=0CBIQ6AEwAg#v=onepage&amp;q=la%20spirale%20Georges%20Migot&amp;f=false">La Spirale</a> and <a href="http://www.britannica.com/EBchecked/topic/303331/La-Jeune-France">La Jeune France</a>. La Spirale was founded in 1935 under the leadership of Georges Migot; its other committee members were Paul Le Flem, his pupil André Jolivet, Edouard Sciortino, Claire Delbos, her husband <a href="http://en.wikipedia.org/wiki/Olivier_Messiaen">Olivier Messiaen</a>, Daniel-Lesur and Jules Le Febvre. The common link between almost all of these musicians was their connection with the Schola Cantorum.</p>
<p><img decoding="async" style="float:left;margin-right:10px;" src="https://lievenlebruyn.github.io/neverendingbooks/DATA2/JeuneFrance.jpg">On the left : Les Jeunes Musiciens Français : André Jolivet on the Piano. Standing from left to right :<br />
Olivier Messiaen, Yves Baudrier, Daniel-Lesur.</p>
<p>Nigel Simeone wrote <a href="http://www.musicaltimes.co.uk/archive/0203/simeone.html">this</a> about Messiaen and La Jeune France :<br />
&#8220;The extremely original and independent-minded Messiaen had already shown himself to be a rather unexpected enthusiast for joining groups: in December 1932 he wrote to his friend Claude Arrieu about a letter from another musician, Jacques Porte, outlining plans for a new society to be called Les Jeunes Musiciens Français.<br />
Messiaen agreed to become its vice-president, but nothing seems to have come of the project. Six months later, in June 1933, he had a frustrating meeting with Roger Désormière on behalf of the composers he described to Arrieu as ‘les quatre’, all of them Dukas pupils: Elsa Barraine, <strong>the recently-deceased Jean Cartan</strong>, Arrieu and Messiaen himself; during the early 1930s Messiaen and Arrieu organised concerts featuring all four composers.&#8221;</p>
<p><img decoding="async" src="https://lievenlebruyn.github.io/neverendingbooks/DATA2/Cartanfamily.jpg" style="float:right;margin-left:10px;" hspace=10>Finally, we&#8217;re getting a connection with the Bourbaki group! Norbert Dufourcq mentioned it already in his comment &#8220;Messiaen was also a good friend of Jean Cartan (himself a composer, and Henri’s brother)&#8221;. <a href="http://en.wikipedia.org/wiki/Henri_Cartan">Henri Cartan</a> was one of the first Bourbakis and an excellent piano player himself.</p>
<p>The Cartan family picture on the right : standing from left to right, father <a href="http://en.wikipedia.org/wiki/Élie_Cartan">Elie Cartan</a> (one of the few older French mathematicians respected by the Bourbakis), Henri and his mother Marie-Louise. Seated, the younger children, from left to right : Louis, Helene (who later became a mathematician, herself) and the composer Jean Cartan, who sadly died very young from tuberculoses in 1932&#8230;</p>
<p>The december 1934 revolution in French music at the Schola Cantorum, instigated by Messiaen and followers, was the culmination of a process that started a few years before when Jean Cartan was among the circle of revolutionados. Because Messiaen was a fiend of the Cartan family, they surely must have been aware of the events at the Schola (or because it was merely a block away from the ENS), and, the musicians&#8217; revolt may very well have been an example to follow for the first Bourbakis&#8230;(?!)</p>
<p>Anyway, we now know the intended meaning of the line &#8220;with lemmas sung by the Scholia Cartanorum&#8221; on the wedding-invitation. Cartanorum is NOT (as I <a href="https://lievenlebruyn.github.io/neverendingbooks/index.php/where-was-the-bourbaki-wedding.html">claimed last time</a>) bad Latin for &#8216;Cartesiorum&#8217;, leading to Descartes and the Saint-Germain-des-Pres church, but is in fact passable Latin (plur. gen.) of CARTAN(us), whence the translation &#8220;with lemmas sung by the school of the Cartans&#8221;. There&#8217;s possibly a double pun intended here : first, a reference to (father) <a href="http://www.joensuu.fi/matematiikka/kurssit/complex/luku10.pdf">Cartan&#8217;s lemma</a> and, of course, to La Schola where the musical Cartan-family felt at home.</p>
<p><img decoding="async" src="https://lievenlebruyn.github.io/neverendingbooks/DATA2/valdeGrace1.jpg" style="float:left;margin-right:10px;" hspace=10> Fine, but does this brings us any closer to the intended place of the Bourbaki-Petard wedding? Well, let&#8217;s reconsider the hidden &#8216;clues&#8217; we discovered last time : the phrase &#8220;They will receive the trivial isomorphism from P. Adic, of the Order of the Diophantines&#8221; might suggest that the church belongs to a a religious order and is perhaps an abbey- or convent-church and the phrase &#8220;the organ will be played by Monsieur Modulo&#8221; requires us to identify this mysterious Mister Modulo, because Norbert Dufourcq rightfully observed :</p>
<p>&#8220;note however that in 1939, it wasn’t as common to have a friend-organist perform at a wedding as it is today: the appointed organists, especially at prestigious Paris positions, were much less likely to accept someone play in their stead.&#8221;</p>
<p>The <a href="http://www.schola-cantorum.com/histoire.php">history</a> of La Schola Cantorum reveals something that might have amused Frank Smithies (<a href="https://lievenlebruyn.github.io/neverendingbooks/index.php/when-was-the-bourbaki-wedding.html">remember</a> he was one of the wedding-invitation-composers) : the Schola is located in the Convent(!) of the Brittish  Benedictines&#8230;</p>
<p>In 1640 some Benedictine monks, on the run after the religious schism in Britain, found safety in Paris under the protection of <a href="http://en.wikipedia.org/wiki/Cardinal_Richelieu">Cardinal Richelieu</a> and <a href="http://en.wikipedia.org/wiki/Anne_of_Austria">Anne of Austria</a> at <a href="http://en.wikipedia.org/wiki/Val-de-Grâce">Val-de-Grace</a>, where the Schola is now housed.</p>
<p>As is the case with most convents, the convent of the Brittish Benedictines did have its own convent church, now called <a href="http://perso.magic.fr/desarbre/pages/page3.html">l&#8217;église royale Notre-Dame du Val-de-Grâce</a> (remember that one of the possible interpretations for &#8220;of the universal variety&#8221; was that the name of the church would be &#8220;Notre-Dame&#8221;&#8230;).</p>
<p><img decoding="async" src="https://lievenlebruyn.github.io/neverendingbooks/DATA2/valdeGrace2.jpg" style="float:right;margin-left:10px;" hspace=10> This church is presently used as the concert hall of La Schola and is famous for its &#8230; <a href="http://www.valdegrace.org/pages/page4.html">musical organ</a> : &#8220;In 1853, <a href="http://en.wikipedia.org/wiki/Aristide_Cavaillé-Coll">Aristide Cavaillé-Coll</a> installed a new organ in the Church of Sainte-geneviève which had been restored in its rôle as a place of worship by Prince President Louis-Napoléon. In 1885, upon the decision of President Jules Grévy, this church once again became the Pantheon and, six years later, according to an understanding between the War and Public Works Departments, the organ was transferred to the Val-de-Grâce, under the supervision of the organ builder Merklin. Beforehand, the last time it was heard in the Pantheon must have been for the funeral service of Victor Hugo.<br />
In 1927, a raising was carried out by the builder Paul-Marie Koenig, and the inaugural concert was given by André Marchal and Achille Philippe, the church’s organist. Added to the register of historic monument in 1979, Val-de-Grâce’s “ little great organ ”, as Cavaillé-Coll called it, was restored in 1993 by the organ builders François Delangue and Bernard Hurvy.<br />
The organ of Val-de-Grâce is one the rare parisian surviving witnesses of the art of Aristide Cavaillé-Coll, an instrument that escaped abusive and definitive transformations or modernizations. This explain why, in spite of its relatively modest scale, this organ enjoys quite a reputation, and this, as far as the United States.&#8221;</p>
<p>By why would the Val-de-Grace organiste at the time <a href="http://fr.wikipedia.org/wiki/Achille_Philip">Achille Philip</a>, &#8220;organiste titulaire du Val-de-Grâce de 1903 à 1950 et professeur d&#8217;orgue et d&#8217;harmonie à la Schola Cantorum de 1904 à 1950&#8221;, be called &#8216;Mister Modulo&#8217; in the wedding-invitations line &#8220;L&#8217;orgue sera tenu par Monsieur Modulo&#8221;???</p>
<p>Again, the late Norbert Dufourcq comes to our rescue, proposing a good candidate for &#8216;Monsieur Modulo&#8217; : &#8220;As for “modulo”, note that the organist at Notre-Dame at that time, Léonce de Saint-Martin, was also the composer of a “Suite Cyclique”, though I admit that this is just wordplay: there is nothing “modular” about this work. Maybe a more serious candidate would be <a href="http://en.wikipedia.org/wiki/Olivier_Messiaen">Olivier Messiaen</a> (who was organist at the Église de la Trinité): his “modes à transposition limitée” are really about Z/12Z→Z/3Z and Z/12Z→Z/4Z. &#8220;</p>
<p><img decoding="async" src="https://lievenlebruyn.github.io/neverendingbooks/DATA2/messi.jpg" style="float:left;margin-right:10px;" hspace=10> Messiaen&#8217;s <a href="http://en.wikipedia.org/wiki/Modes_of_limited_transposition">&#8216;Modes of limited transposition&#8217;</a> were compiled in his book &#8216;Technique de mon langage musical&#8217;. This book was published in Paris by  Leduc, as late as 1944, 5 years after the wedding-invitation.</p>
<p>Still, several earlier works of Messiaen used these schemes, most notably <a href="http://en.wikipedia.org/wiki/La_Nativité_du_Seigneur">La Nativité du Seigneur</a>, composed in 1935 : &#8220;The work is one of the earliest to feature elements that were to become key to Messiaen&#8217;s later compositions, such as the extensive use of the composer&#8217;s own modes of limited transposition, as well as influence from birdsong, and the meters and rhythms of Ancient Greek and traditional Indian music.&#8221;</p>
<p>More details on Messiaen&#8217;s modes and their connection to modular arithmetic can be found in the study <a href="http://www.vjmanzo.com/clients/vincemanzo/scores/Implementing%20Modality%20in%20Algorithmic%20Composition.pdf">Implementing Modality in Algorithmic Composition</a> by Vincent Joseph Manzo.</p>
<p>Hence, Messiaen is a suitable candidate for the title &#8216;Monsieur Modulo&#8217;, but would he be able to play the Val-de-Grace organ while not being the resident organist?</p>
<p>Remember, the Val-de-Grace church was the concert hall of La Schola, and its musical organ the instrument of choice for the relevant courses. Now &#8230; Olivier Messiaen <a href="http://www.encyclopedia.com/topic/Olivier_Messiaen.aspx">taught</a> at the Schola Cantorum and the École Normale de Musique  from 1936 till 1939. So, at the <a href="https://lievenlebruyn.github.io/neverendingbooks/index.php/when-was-the-bourbaki-wedding.html">time of the Bourbaki-Petard wedding</a> he would certainly be allowed to play the  Cavaillé-Coll organ.</p>
<p>Perhaps we got it right, the second time around : <strong>the Bourbaki-Pétard wedding was held on June 3rd 1939 in the church &#8216;l&#8217;église royale Notre-Dame du Val-de-Grâce&#8217; at 12h</strong>?</p>
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		<title>Grothendieck’s functor of points</title>
		<link>https://lievenlebruyn.github.io/neverendingbooks/grothendiecks-functor-of-points/</link>
		
		<dc:creator><![CDATA[lieven]]></dc:creator>
		<pubDate>Tue, 29 Sep 2009 06:17:06 +0000</pubDate>
				<category><![CDATA[geometry]]></category>
		<category><![CDATA[math]]></category>
		<category><![CDATA[blogging]]></category>
		<category><![CDATA[Grothendieck]]></category>
		<category><![CDATA[teaching]]></category>
		<category><![CDATA[wordpress]]></category>
		<guid isPermaLink="false">http://www.neverendingbooks.org/?p=562</guid>

					<description><![CDATA[A comment-thread well worth following while on vacation was Algebraic Geometry without Prime Ideals at the Secret Blogging Seminar. Peter Woit became lyric about it&#8230;]]></description>
										<content:encoded><![CDATA[<p>A comment-thread well worth following while on vacation was <a href="http://sbseminar.wordpress.com/2009/08/06/algebraic-geometry-without-prime-ideals/">Algebraic Geometry without Prime Ideals</a> at the Secret Blogging Seminar. Peter Woit became <a href="http://www.math.columbia.edu/~woit/wordpress/?p=2240">lyric about it</a> :</p>
<blockquote><p>
My nomination for the all-time highest quality discussion ever held in a blog comment section goes to the comments on this posting at Secret Blogging Seminar, where several of the best (relatively)-young algebraic geometers in the business discuss the foundations of the subject and how it should be taught.
</p></blockquote>
<p>I follow far too few comment-sections to make such a definite statement, but found the contributions by <a href="http://wwwmaths.anu.edu.au/~borger/">James Borger</a> and <a href="http://www.ma.utexas.edu/users/benzvi/">David Ben-Zvi</a> of exceptional high quality. They made a case for using Grothendieck&#8217;s &#8216;functor of points&#8217; approach in teaching algebraic geometry instead of the &#8216;usual&#8217; approach via prime spectra and their structure sheaves.</p>
<p>The text below was written on december 15th of last year, but never posted. As far as I recall it was meant to be part two of the &#8216;Brave New Geometries&#8217;-series starting with the <a href="https://lievenlebruyn.github.io/neverendingbooks/index.php/mumfords-treasure-map.html">Mumford&#8217;s treasure map</a> post. Anyway, it may perhaps serve someone unfamiliar with Grothendieck&#8217;s functorial approach to make the first few timid steps in that directions.</p>
<p><img decoding="async" src="https://lievenlebruyn.github.io/neverendingbooks/DATA2/GrothendieckP.jpg" style="float:right;margin-left:10px;"><a href="http://www.ams.org/staff/jackson/articles.html">Allyn Jackson&#8217;s</a> beautiful account of Grothendieck&#8217;s life &#8220;<a href="http://www.math.jussieu.fr/~leila/grothendieckcircle/allyn2.pdf">Comme Appele du Neant, part II</a>&#8221; (the first part of the paper can be found <a href="http://www.math.jussieu.fr/~leila/grothendieckcircle/allyn1.pdf">here</a>) contains this gem :</p>
<p>&#8220;One striking characteristic of Grothendieck’s<br />
mode of thinking is that it seemed to rely so little<br />
on examples. This can be seen in the legend of the<br />
so-called “<a href="http://en.wikipedia.org/wiki/57_(number)">Grothendieck prime</a>”.</p>
<p>In a mathematical<br />
conversation, someone suggested to Grothendieck<br />
that they should consider a particular prime number.<br />
“You mean an actual number?” Grothendieck<br />
asked. The other person replied, yes, an actual<br />
prime number. Grothendieck suggested, “All right,<br />
take 57.”</p>
<p>But Grothendieck must have known that 57 is not<br />
prime, right? Absolutely not, said David Mumford<br />
of Brown University. “He doesn’t think concretely.”&#8221;</p>
<p>We have seen before how Mumford&#8217;s <a href="https://lievenlebruyn.github.io/neverendingbooks/index.php/mumfords-treasure-map.html">doodles</a> allow us to depict all &#8216;points&#8217; of the affine scheme $\mathbf{spec}(\mathbb{Z}[x]) $, that is, all prime ideals of the integral polynomial ring $\mathbb{Z}[x] $.<br />
Perhaps not too surprising, in view of the above story, <a href="http://en.wikipedia.org/wiki/Alexander_Grothendieck">Alexander Grothendieck</a> pushed the view that one should consider all ideals, rather than just the primes. He achieved this by associating the &#8216;functor of points&#8217; to an affine scheme.</p>
<p>Consider an arbitrary affine integral scheme $X $ with coordinate ring $\mathbb{Z}[X] = \mathbb{Z}[t_1,\ldots,t_n]/(f_1,\ldots,f_k) $, then any ringmorphism<br />
$\phi~:~\mathbb{Z}[t_1,\ldots,t_n]/(f_1,\ldots,f_k) \rightarrow R $<br />
is determined by an n-tuple of elements $~(r_1,\ldots,r_n) = (\phi(t_1),\ldots,\phi(t_n)) $ from $R $ which must satisfy the polynomial relations $f_i(r_1,\ldots,r_n)=0 $. Thus, Grothendieck argued, one can consider $~(r_1,\ldots,r_n) $ an an &#8216;$R $-point&#8217; of $X $ and all such tuples form a set $h_X(R) $ called the set of $R $-points of $X $. But then we have a <a href="http://en.wikipedia.org/wiki/Functor">functor</a></p>
<p>$h_X~:~\mathbf{commutative rings} \rightarrow \mathbf{sets} \qquad R \mapsto h_X(R)=Rings(\mathbb{Z}[t_1,\ldots,t_n]/(f_1,\ldots,f_k),R) $</p>
<p>So, what is this mysterious functor in the special case of interest to us, that is when $X = \mathbf{spec}(\mathbb{Z}[x]) $?<br />
Well, in that case there are no relations to be satisfied so any ringmorphism $\mathbb{Z}[x] \rightarrow R $ is fully determined by the image of $x $ which can be any element $r \in R $. That is, $Ring(\mathbb{Z}[x],R) = R $ and therefore Grothendieck&#8217;s functor of points<br />
$h_{\mathbf{spec}(\mathbb{Z}[x]} $ is nothing but the <a href="http://en.wikipedia.org/wiki/Forgetful_functor">forgetful functor</a>.</p>
<p>But, surely the forgetful functor cannot give us interesting extra information on Mumford&#8217;s drawing?<br />
Well, have a look at the slightly extended drawing below :</p>
<p><center><br />
<img decoding="async" src="https://lievenlebruyn.github.io/neverendingbooks/DATA2/GrothMumford.jpg"><br />
</center></p>
<p>What are these &#8216;smudgy&#8217; lines and &#8216;spiky&#8217; points? Well, before we come to those let us consider the easier case of identifying the $R $-points in case $R $ is a domain. Then, for any $r \in R $, the inverse image of the zero prime ideal of $R $ under the ringmap $\phi_r~:~\mathbb{Z}[x] \rightarrow R $ must be a prime ideal of $\mathbb{Z}[x] $, that is, something visible in Mumford&#8217;s drawing. Let&#8217;s consider a few easy cases :</p>
<p><img decoding="async" src="https://lievenlebruyn.github.io/neverendingbooks/DATA2/GrothMum1.jpg" style="float:right;margin-left:10px;"> For starters, what are the $\mathbb{Z} $-points of $\mathbf{spec}(\mathbb{Z}[x]) $? Any natural number $n \in \mathbb{Z} $ determines the surjective ringmorphism $\phi_n~:~\mathbb{Z}[x] \rightarrow \mathbb{Z} $ identifying $\mathbb{Z} $ with the quotient $\mathbb{Z}[x]/(x-n) $, identifying the &#8216;arithmetic line&#8217; $\mathbf{spec}(\mathbb{Z}) = &#123; (2),(3),(5),\ldots,(p),\ldots, (0) &#125; $ with the horizontal line in $\mathbf{spec}(\mathbb{Z}[x]) $ corresponding to the principal ideal $~(x-n) $ (such as the indicated line $~(x) $).</p>
<p>When $\mathbb{Q} $ are the rational numbers, then $\lambda = \frac{m}{n} $ with $m,n $ coprime integers, in which case we have $\phi_{\lambda}^{-1}(0) = (nx-m) $, hence we get again an horizontal line in $\mathbf{spec}(\mathbb{Z}[x]) $. For $ \overline{\mathbb{Q}} $, the algebraic closure of $\mathbb{Q} $ we have for any $\lambda $ that $\phi_{\lambda}^{-1}(0) = (f(x)) $ where $f(x) $ is a minimal integral polynomial for which $\lambda $ is a root.<br />
But what happens when $K = \mathbb{C} $ and $\lambda $ is a trancendental number? Well, in that case the ringmorphism $\phi_{\lambda}~:~\mathbb{Z}[x] \rightarrow \mathbb{C} $ is injective and therefore $\phi_{\lambda}^{-1}(0) = (0) $ so  we get the whole arithmetic plane!</p>
<p>In the case of a finite field $\mathbb{F}_{p^n} $ we have seen that there are &#8216;fat&#8217; points in the arithmetic plane, corresponding to maximal ideals $~(p,f(x)) $ (with $f(x) $ a polynomial of degree $n $ which remains irreducible over $\mathbb{F}_p $), having $\mathbb{F}_{p^n} $ as their residue field. But these are not the only $\mathbb{F}_{p^n} $-points. For, take any element $\lambda \in \mathbb{F}_{p^n} $, then the map $\phi_{\lambda} $ takes $\mathbb{Z}[x] $ to the subfield of $\mathbb{F}_{p^n} $ generated by $\lambda $. That is, the $\mathbb{F}_{p^n} $-points of $\mathbf{spec}(\mathbb{Z}[x]) $ consists of all fat points with residue field $\mathbb{F}_{p^n} $, together with slightly slimmer points having as their residue field $\mathbb{F}_{p^m} $ where $m $ is a divisor of $n $. In all, there are precisely $p^n $ (that is, the number of elements of $\mathbb{F}_{p^n} $) such points, as could be expected.</p>
<p>Things become quickly more interesting when we consider $R $-points for rings containing nilpotent elements.</p>
]]></content:encoded>
					
		
		
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		<item>
		<title>Don’t realize how lucky I am</title>
		<link>https://lievenlebruyn.github.io/neverendingbooks/dont-realize-how-lucky-i-am/</link>
		
		<dc:creator><![CDATA[lieven]]></dc:creator>
		<pubDate>Sun, 27 Sep 2009 07:47:52 +0000</pubDate>
				<category><![CDATA[stories]]></category>
		<category><![CDATA[teaching]]></category>
		<guid isPermaLink="false">http://www.neverendingbooks.org/?p=2129</guid>

					<description><![CDATA[After a difficult time for us all, PD1 tells me she finally &#8216;found her drive&#8217; again : she hopes to finish her 2nd(!) master in&#8230;]]></description>
										<content:encoded><![CDATA[<p>After a difficult time for us all, PD1 tells me she finally &#8216;found her drive&#8217; again : she hopes to finish her 2nd(!) master in fine arts this year as well as her teaching-diplome. Besides, she teaches evening arts-classes twice a week, organizes exhibitions, enters competitions, wins prizes &#8230; Looking at the time-stamps on her emails, there are simply not enough hours in a day to fulfill her many ambitions.</p>
<p>Yesterday she made a blitz-appearance, on her way to a variety of exciting other encounters.</p>
<p>PD1 : And, what about you? A lot of teaching this year?</p>
<p>me : Yes (sigh), the first semester is really hard. I&#8217;ve an obligatory 60 hours course in each of the three bachelor years, and two courses in the masters. Fortunately, the master-students all wanted a different topic, so they only pop in to ask questions when they get stuck with their reading courses. But still, officially I&#8217;ll be teaching 300 hours before christmas.</p>
<p>PD1 : Yeah, yeah, officially&#8230; But, then there are exercises and so. How much time do you really have to teach in front of a blackboard?</p>
<p>me : Well, let&#8217;s see. Wednesday afternoon I have the 2nd year, thursday afternoon the first and friday morning the third year.</p>
<p>PD1 : Is that all?</p>
<p>me : huh? Yes&#8230;</p>
<p>PD1 : Wow! You only have to teach three half days a week and can spend all your other time  doing mathematics! A pretty good deal isn&#8217;t it?</p>
<p>me : Yeah, I guess I don&#8217;t realize often enough just how lucky I am &#8230;</p>
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		<title>return of the cat ceilidh</title>
		<link>https://lievenlebruyn.github.io/neverendingbooks/return-of-the-cat-ceilidh/</link>
					<comments>https://lievenlebruyn.github.io/neverendingbooks/return-of-the-cat-ceilidh/#respond</comments>
		
		<dc:creator><![CDATA[lieven]]></dc:creator>
		<pubDate>Thu, 24 Jan 2008 11:46:11 +0000</pubDate>
				<category><![CDATA[stories]]></category>
		<category><![CDATA[cryptography]]></category>
		<category><![CDATA[google]]></category>
		<category><![CDATA[teaching]]></category>
		<guid isPermaLink="false">http://www.neverendingbooks.org/index.php/return-of-the-cat-ceilidh.html</guid>

					<description><![CDATA[I couldn&#8217;t believe my eyes. I was watching an episode of numb3rs, &#8216;undercurrents&#8217; to be precise, and there it was, circled in the middle of&#8230;]]></description>
										<content:encoded><![CDATA[<p>I couldn&#8217;t believe my eyes. I was watching an episode of <a href="http://www.cbs.com/primetime/numb3rs/">numb3rs</a>, &#8216;undercurrents&#8217; to be precise, and there it was, circled in the middle of the blackboard, <a href="https://lievenlebruyn.github.io/neverendingbooks/index.php/a-cat-called-ceilidh.html">CEILIDH</a>, together with some of the key-exchange maps around it&#8230;</p>
<p><img decoding="async" src="https://lievenlebruyn.github.io/neverendingbooks/DATA/ceilidhnumbers.jpg" ></p>
<p>Only, the plot doesn&#8217;t involve any tori-crypto&#8230; okay, there is an I-Ching-coded-tattoo which turns out to be a telephone number, but that&#8217;s all. Still, this couldn&#8217;t just be a coincidence. Googling for &#8216;<a href="http://www.google.com/search?client=safari&amp;rls=en-us&amp;q=ceilidh%2Bnumb3rs&amp;ie=UTF-8&amp;oe=UTF-8">ceilidh+numbers</a>&#8216; gives as top hit the pdf-file of an article <a href="http://math.uci.edu/~asilverb/bibliography/numb3rland.pdf">Alice in NUMB3Rland</a> written by &#8230; Alice Silverberg (of the Rubin-Silverberg paper starting tori-cryptography). Alice turns out to be one of the unpaid consultants to the series. The 2-page article gives some insight into how &#8216;some math&#8217; gets into the script</p>
<blockquote><p>Typically, Andy emails a draft of the<br />
script to the consultants. The FBI plot<br />
is already in place, and the writers want<br />
mathematics to go with it. The placeholder &#8220;math&#8221; in the draft is often nonsense or<br />
jargon; the sort of things people with no<br />
mathematical background might find by<br />
Googling, and think was real math. Since<br />
there&#8217;s often no mathematics that makes<br />
sense in those parts of the script, the best<br />
the consultants can do is replace jargon<br />
that makes us cringe a lot with jargon that<br />
makes us cringe a little. </p>
<p>From then on, it&#8217;s the Telephone Game.<br />
The consultants email Andy our suggestions (&#8220;replace &#8216;our discrete universes&#8217;<br />
with &#8216;our disjoint universes'&#8221;; &#8220;replace<br />
the nonsensical &#8216;we&#8217;ve tried everything<br />
-a full frequency analysis, a Vignere<br />
deconstruction- we even checked for<br />
a Lucas sequence&#8217; with the slightly less<br />
nonsensical &#8216;It&#8217;s much too short to try<br />
any cryptanalysis on. If it were longer<br />
we could try frequency analyses, or try<br />
to guess what kind of cryptosystem it is<br />
and use a specialized technique. For example, if it were a long enough Vigenere<br />
cipher we could try a Kasiski test or an<br />
index-of-coincidence analysis&#8217;). Andy<br />
chooses about a quarter of my sugges-<br />
tions and forwards his interpretation<br />
of them to the writers and producers.<br />
The script gets changed, and then the<br />
actors ad lib something completely dif-<br />
ferent (&#8216;disjointed universes&#8217;: cute, but<br />
loses the mathematical allusion; &#8216;Kasiski<br />
exam&#8217; : I didn&#8217;t mean that kind of &#8216;test&#8217;).
</p></blockquote>
<p>She ends her article with :</p>
<blockquote><p>I have mixed feelings about NUMB3RS.  I still have concerns about the violence, the depiction of women, and the pretense<br />
that the math is accurate. However, if NUMB3RS could interest people in the power of mathematics enough for society<br />
to greater value and support mathematics teaching, learning, and research, and<br />
motivate more students to learnthat would be a positive step. </p></blockquote>
<p>Further, there is a whole blog dedicated to some of the maths featuring in NUMB3RS, the <a href="http://www.atsweb.neu.edu/math/cp/blog/?showall=yes">numb3rs blog</a>. And it was the first time I had to take a screenshot of a DVD, something usually off limits to the grab.app, but there is a <a href="http://highschoolblows.blogspot.com/2005/11/take-screenshot-of-dvd-player-in-os-x.html">simple hack</a> to do it&#8230;</p>
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		<title>NeverEndingBooks-general</title>
		<link>https://lievenlebruyn.github.io/neverendingbooks/neverendingbooks-general/</link>
					<comments>https://lievenlebruyn.github.io/neverendingbooks/neverendingbooks-general/#respond</comments>
		
		<dc:creator><![CDATA[lieven]]></dc:creator>
		<pubDate>Tue, 12 Jun 2007 13:17:35 +0000</pubDate>
				<category><![CDATA[stories]]></category>
		<category><![CDATA[arxiv]]></category>
		<category><![CDATA[blogging]]></category>
		<category><![CDATA[GMD]]></category>
		<category><![CDATA[google]]></category>
		<category><![CDATA[LaTeX]]></category>
		<category><![CDATA[latexrender]]></category>
		<category><![CDATA[Riemann]]></category>
		<category><![CDATA[teaching]]></category>
		<category><![CDATA[Tiger]]></category>
		<category><![CDATA[wordpress]]></category>
		<guid isPermaLink="false">http://localhost/?p=8</guid>

					<description><![CDATA[Here a list of pdf-files of NeverEndingBooks-posts on general topics, in reverse chronological order. Bloomsday end Group think 2 Down with determinants Group think MathML&#8230;]]></description>
										<content:encoded><![CDATA[<p>Here a list of pdf-files of NeverEndingBooks-posts on general topics, in reverse chronological order.</p>
<p><span id="more-12054"></span></p>
<p><a href="NEBPDFS/323.pdf">Bloomsday end</a></p>
<p><a href="NEBPDFS/322.pdf">Group think 2</a></p>
<p><a href="NEBPDFS/321.pdf">Down with determinants</a></p>
<p><a href="NEBPDFS/317.pdf">Group think</a></p>
<p><a href="NEBPDFS/310.pdf">MathML versus LatexRender</a></p>
<p><a href="NEBPDFS/303.pdf">Stalking the Riemann hypothesis</a></p>
<p><a href="NEBPDFS/238.pdf">MathML and work ahead</a></p>
<p><a href="NEBPDFS/234.pdf">The secret life of numbers</a></p>
<p><a href="NEBPDFS/220.pdf">CCDantas on blogging</a></p>
<p><a href="NEBPDFS/211.pdf">Doing the Perelman</a></p>
<p><a href="NEBPDFS/206.pdf">The n-category cafe</a></p>
<p><a href="NEBPDFS/190.pdf">Writing with gloves on</a></p>
<p><a href="NEBPDFS/179.pdf">Why mathematicians cannot write</a></p>
<p><a href="NEBPDFS/178.pdf">The music of the primes</a></p>
<p><a href="NEBPDFS/173.pdf">arXiv trackback wars</a></p>
<p><a href="NEBPDFS/146.pdf">citeUlike</a></p>
<p><a href="NEBPDFS/143.pdf">The efficient academic</a></p>
<p><a href="NEBPDFS/20.pdf">2005 lists : math novels</a></p>
<p><a href="NEBPDFS/16.pdf">Teaching mathematics</a></p>
<p><a href="NEBPDFS/14.pdf">Two TA Tales</a></p>
<p><a href="NEBPDFS/10.pdf">The Oxford murders</a></p>
<p><a href="NEBPDFS/9.pdf">Mappalujo</a></p>
<p><a href="NEBPDFS/3.pdf">LatexRender Plugin for WordPress under Tiger</a></p>
<p><a href="NEBPDFS/57.pdf">GMD</a></p>
<p><a href="NEBPDFS/268.pdf">Google scholar</a></p>
<p><a href="NEBPDFS/249.pdf">Simonne Stevens (1926-2004)</a></p>
<p><a href="NEBPDFS/32.pdf">Quiver pictures in WordPress</a></p>
<p><a href="NEBPDFS/136.pdf">Groen moet!</a></p>
<p><a href="NEBPDFS/132.pdf">Artistic (and other) frustrations</a></p>
<p><a href="NEBPDFS/94.pdf">The cpu 2 generation</a></p>
]]></content:encoded>
					
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		<title>44 32’28.29″N, 4 05’08.61″E</title>
		<link>https://lievenlebruyn.github.io/neverendingbooks/44-322829n-4-050861e/</link>
					<comments>https://lievenlebruyn.github.io/neverendingbooks/44-322829n-4-050861e/#respond</comments>
		
		<dc:creator><![CDATA[lieven]]></dc:creator>
		<pubDate>Mon, 16 Apr 2007 08:16:44 +0000</pubDate>
				<category><![CDATA[stories]]></category>
		<category><![CDATA[google]]></category>
		<category><![CDATA[teaching]]></category>
		<guid isPermaLink="false">http://www.neverendingbooks.org/?p=298</guid>

					<description><![CDATA[Twenty five years ago I was amazed that writing merely &#8220;Le Travers,Sablieres,France&#8221; on an envelop did the job. Today I&#8217;m even more surprised that typing&#8230;]]></description>
										<content:encoded><![CDATA[<p>Twenty<br />
five years ago I was amazed that writing merely &#8220;Le<br />
Travers,Sablieres,France&#8221; on an envelop did the job. Today I&#8217;m even more<br />
surprised that typing just &#8220;Le Travers,Sablieres&#8221; into <a href="http://maps.google.com/">Google Maps</a> or <a href="http://earth.google.com/">Google earth</a> brings you there in seconds with an<br />
offset of about 100 meters!</p>
<p><img decoding="async" src="https://lievenlebruyn.github.io/neverendingbooks/DATA/letraverssablieres.jpg"></p>
<p>Actually, the Google mark may be more accurate as it depicts the spot on<br />
an old mule-path entering &#8216;le hameau de travers&#8217; which consists of two<br />
main buildings : &#8216;le by&#8217; just below us and what we call &#8216;the travers&#8217;<br />
but locals prefer to call &#8216;le jarlier&#8217; or &#8216;garlelier&#8217; or whathever (no<br />
consistent spelling for the house-name yet). If you are French and know<br />
the correct spelling, please leave a comment (it may have to do<br />
something with making baskets and/or pottery).</p>
<p><img decoding="async" src="https://lievenlebruyn.github.io/neverendingbooks/DATA/travers2.jpg"  ></p>
<p>I&#8217;ve always<br />
thought the building dated from the late 18th century, but now they tell<br />
me part of it may actually be a lot older. How they decide this is<br />
pretty funny : around the buildings is a regular grid of old chestnut<br />
trees and as most of them are around 400 years old, so must be the<br />
core-building, which was extended over time to accomodate the growing<br />
number of people and animals, until some 100 yrs ago when the place was<br />
deserted and became ruins&#8230;</p>
<p><img decoding="async" src="https://lievenlebruyn.github.io/neverendingbooks/DATA/traversbomen.jpg"  ></p>
<p>The first<br />
few days biking conditions were excellent. If you ever come to visit or<br />
will be in the neighborhood and are in for an easy (resp. demanding,<br />
resp. tough) one and a half hour ride here, are some suggestions.</p>
<p><img decoding="async" src="https://lievenlebruyn.github.io/neverendingbooks/DATA/fietsroutes.jpg"  ></p>
<p>Start/end<br />
point is always the end of the loose green path in the middle (le<br />
travers). An easy but quite nice route to get a feel for the<br />
surroundings is the yellowish loop (gooing back over blue/green) from<br />
Sablieres to Orcieres and gooing back along camping La Drobie. Slighly<br />
more demanding is the blue climb to over 900 meters to Peyre (and back).<br />
By far the nicest (but also hardest) small tour is the green one<br />
(Dompnac-Pourcharesse-St.Melany). If you want to study<br />
these routes in more detail using GoogleEarth <a href="https://lievenlebruyn.github.io/neverendingbooks/DATA/fietsroutes.kmz">here is the kmz-file</a>. Btw.<br />
this file was obtained from my GPS gpx-file using<br />
<a href="http://www.gpsvisualizer.com/">GPS-visualizer</a>.  Two and a half years<br />
ago I managed to <a href="https://lievenlebruyn.github.io/neverendingbooks/?p=257">connect</a> the<br />
place via a slow dial-up line and conjectured that broadband-internet<br />
would never come this far. I may have to reconsider that now as the<br />
village got an offer from <a href="http://www.numeo.fr/">Numeo.fr</a> to set-up a<br />
wireless (??!!) broadband-network with a pretty low subscription&#8230; But,<br />
as no cell-phone provider has yet managed to cover this area, I&#8217;m a bit<br />
doubtful about Numeo&#8217;s bizness-plan. Still, it would be great. Now, all<br />
I have to do is to convince the university-administration that my online<br />
teaching is a lot better than my in-class-act and Ill be taking up<br />
residence here pretty soon&#8230;</p>
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		<title>way too ambitious</title>
		<link>https://lievenlebruyn.github.io/neverendingbooks/way-too-ambitious/</link>
					<comments>https://lievenlebruyn.github.io/neverendingbooks/way-too-ambitious/#respond</comments>
		
		<dc:creator><![CDATA[lieven]]></dc:creator>
		<pubDate>Tue, 30 Jan 2007 19:38:14 +0000</pubDate>
				<category><![CDATA[stories]]></category>
		<category><![CDATA[geometry]]></category>
		<category><![CDATA[Grothendieck]]></category>
		<category><![CDATA[monster]]></category>
		<category><![CDATA[symmetry]]></category>
		<category><![CDATA[teaching]]></category>
		<guid isPermaLink="false">http://www.neverendingbooks.org/?p=92</guid>

					<description><![CDATA[Student-evaluation sneak preview : I am friendly and extremely helpful but have a somewhat chaotic teaching style and am way too ambitious as regards content&#8230;&#8230;]]></description>
										<content:encoded><![CDATA[<p>Student-evaluation sneak preview : I am friendly and<br />
extremely helpful but have a somewhat chaotic teaching style and am way<br />
too ambitious as regards content&#8230; I was about to deny vehemently<br />
all assertions (except for the chaotic bit) but may have to change my<br />
mind after reading <a href="http://cerncourier.com/main/article/46/7/35">this report</a> on<br />
Mark Rowan&#8217;s book &#8216;Symmetry and the monster&#8217; (see also<br />
<a href="https://lievenlebruyn.github.io/neverendingbooks/index.php?p=189">my post</a><br />
)</p>
<blockquote><p> Oxford University Press considers this book<br />
&#8220;a must-read for all fans of popular science&#8221;. In his blog,<br />
Lieven le Bruyn, professor of algebra and geometry at the University of<br />
Antwerp, suggests that &#8220;Mark Ronan has written a beautiful book<br />
intended for the general public&#8221;. However, he goes on to say:<br />
&#8220;this year I&#8217;ve tried to explain  to an exceptionally<br />
good second year of undergraduates, but failed miserably  Perhaps<br />
I&#8217;ll give it another (downkeyed) try using Symmetry and the<br />
Monster as reading material&#8221;. </p>
<p /> As an erstwhile<br />
mathematician, I found the book more suited to exceptional maths<br />
undergraduates than to the general public and would strongly encourage<br />
authors and/or publishers to pass such works before a few fans of<br />
popular science before going to press. </p>
<p /> Peggie Rimmer,<br />
Satigny. </p></blockquote>
<p>Well, this &#8216;exceptionally good<br />
year&#8217; has moved on and I had to teach a course &#8216;Elementary<br />
Algebraic Geometry&#8217; to them last semester. I had the crazy idea to<br />
approach this in a historical perspective : first I did the<br />
Hilbert-Noether period (translating geometry to ideal theory of<br />
polynomial rings), then the Krull-Weil-Zariski period (defining<br />
everything in terms of coordinate rings) to finish off with the<br />
Serre-Grothendieck period (introducing scheme theory)&#8230; Not<br />
surprisingly, I lost everyone after 1920. Once again there were<br />
complaints that I was expecting way too much from them etc. etc. and I<br />
was about to apologize and promise I&#8217;ll stick to a doable course<br />
next year (something along the lines of Miles Reid&#8217;s<br />
&#8216;Undergraduate Algebraic Geometry&#8217;) when one of the students<br />
(admittedly, probably the best of this &#8216;exceptional year&#8217;)<br />
decided to do all exercises of the first two chapters of Fulton&#8217;s<br />
&#8216;Algebraic Curves&#8217; to become more accustomed to the subject.<br />
Afterwards he told me &#8220;You know, I wouldn&#8217;t change the<br />
course too much, now that I did all these exercises I realize that your<br />
course notes are not that bad after all&#8230;&#8221;. Yeah, thanks!</p>
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		<title>attention-span : one chat line</title>
		<link>https://lievenlebruyn.github.io/neverendingbooks/attention-span-one-chat-line/</link>
					<comments>https://lievenlebruyn.github.io/neverendingbooks/attention-span-one-chat-line/#respond</comments>
		
		<dc:creator><![CDATA[lieven]]></dc:creator>
		<pubDate>Tue, 26 Dec 2006 14:20:29 +0000</pubDate>
				<category><![CDATA[stories]]></category>
		<category><![CDATA[teaching]]></category>
		<guid isPermaLink="false">http://www.neverendingbooks.org/?p=89</guid>

					<description><![CDATA[Never spend so much time on teaching than this semester and never felt so depressed afterwards. The final test for the first year course on&#8230;]]></description>
										<content:encoded><![CDATA[<p>Never<br />
spend so much time on teaching than this semester and never felt so<br />
depressed afterwards. The final test for the first year course on<br />
grouptheory (60 hrs. going from nothing to Jordan-Holder and the Sylow<br />
theorems) included the following question :</p>
<p><strong>Question :<br />
</strong> For a subgroup $H \subset G $ define the normalizer to be the<br />
subgroup $N_G(H) = \{ g \in G~:~gHg^{-1} = H \} $. Complete the<br />
statement of the result for which the proof is given<br />
below.</p>
<p><strong>theorem : </strong> Let P be a Sylow subgroup of<br />
a finite group G and suppose that H is a subgroup of G which<br />
contains the normalizer $N_G(P) $. Then &#8230;</p>
<p><strong>proof :<br />
</strong> Let $u \in N_G(H) $. Now, $P \subset N_G(P) \subset H $<br />
whence $uPu^{-1} \subset uHu^{-1} = H $. Thus, $uPu^{-1} $, being of the<br />
same order as P is also a Sylow subgroup op H. Applying the Sylow<br />
theorems to H we infer that there exists an element $h \in H $ such<br />
that<br />$h(uPu^{-1})h^{-1} = P $. This means that $hu \in N_G(P) $.<br />
Since, by hypotheses, $N_G(P) \subset H $, it follows that $hu \in H $.<br />
As $h \in H $ it follows that $u \in H $, finishing the proof.</p>
<p>A<br />
majority of the students was unable to do this&#8230; Sure, the result was<br />
not contained in their course-notes (if it were I\&#8217;m certain all of them<br />
would be able to give the correct statement as well as the full proof<br />
<strong>by heart</strong>. It makes me wonder how much they understood<br />
of the proof of the Sylow-theorems.) They (and others) blame it on the<br />
fact that not every triviality is spelled out in my notes or on my<br />
\&#8217;chaotic\&#8217; teaching-style. I fear the real reason is contained in the<br />
post-title&#8230; </p>
<p>But, I\&#8217;m still lucky to be working with students<br />
who are interested in mathematics. I assume it can get a lot worse (but<br />
also a lot funnier)</p>
<p><img
src="http://www.newsvine.com/_vine/images/users/nws/leestone/459299.jpg
"/></p>
<p>and what about this one :</p>
<p><img decoding="async" src="http://www.newsvine.com/_vine/images/users/nws/leestone/459305.jpg"/></p>
<p>If you are (like me) in urgent need for a smile, try out<br />
this <a href="http://leestone.newsvine.com/_news/2006/11/27/459295-modern-mathematics">newsvine article</a> for more<br />
bloopers.</p>
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		<title>mathematics &#038; unhappiness</title>
		<link>https://lievenlebruyn.github.io/neverendingbooks/mathematics-unhappiness/</link>
					<comments>https://lievenlebruyn.github.io/neverendingbooks/mathematics-unhappiness/#respond</comments>
		
		<dc:creator><![CDATA[lieven]]></dc:creator>
		<pubDate>Mon, 23 Oct 2006 16:27:51 +0000</pubDate>
				<category><![CDATA[stories]]></category>
		<category><![CDATA[teaching]]></category>
		<category><![CDATA[topology]]></category>
		<guid isPermaLink="false">http://www.neverendingbooks.org/?p=80</guid>

					<description><![CDATA[Sociologists are a constant source of enlightenment as CNN keeps reminding Kids who are turned off by math often say they don&#8217;t enjoy it, they&#8230;]]></description>
										<content:encoded><![CDATA[<p>Sociologists are a constant source of enlightenment as CNN keeps <a
href=\"http://edition.cnn.com/2006/EDUCATION/10/18/unhappy.achievers.ap/
index.html\">reminding</a></p>
<blockquote><p> Kids who are turned<br />
off by math often say they don&#8217;t enjoy it, they aren&#8217;t good<br />
at it and they see little point in it. Who knew that could be a formula<br />
for success? <br /> The nations with the best scores have the<br />
least happy, least confident math students, says a study by the<br />
Brookings Institution&#8217;s Brown Center on Education Policy. <br
/> Countries reporting higher levels of enjoyment and confidence<br />
among math students don&#8217;t do as well in the subject, the study<br />
suggests. <br /> The eighth-grade results reflected a common<br />
pattern: The 10 nations whose students enjoyed math the most all scored<br />
below average. The bottom 10 nations on the enjoyment scale all<br />
excelled. </p></blockquote>
<p><img decoding="async" src="https://lievenlebruyn.github.io/neverendingbooks/DATA/tims.jpg" /></p>
<p>As this study is based on the <a
href=\"http://timss.bc.edu/timss2003.html\">2003 Trends in International<br />
Mathematics and Science Studies</a> and as &#8220;we&#8221; scored best<br />
of all western countries<br />
 this<br />
probably explains all the unhappy faces in my first-year class on group<br />
theory. However, they seemed quite happy the first few weeks.<br />
Fortunately, this is proof, at least according to the <a
href=\"http://motls.blogspot.com/2006/10/cnn-happiness-confidence-bad-
for.html\">mountain of wisdom</a>, that I&#8217;m on the right track</p>
<blockquote><p> If too many students are too happy in the math<br />
classes, be sure that it is simply because not much is expected from<br />
them. It can&#8217;t be otherwise. If teaching of mathematics is<br />
efficient, it is almost guaranteed that a large group or a majority must<br />
dislike the math classes. Mathematics is hard and if it is not hard, it<br />
is not mathematics. </p></blockquote>
<p>Right on! But then, why is<br />
it that people willing to study maths enter university in a happy mood?<br />
Oh, I get it, yes, it must be because in secondary school not much was<br />
expected of them! Ouf! my entire world is consistent once again.<br />
But then, hey wait, the next big thing that&#8217;s inevitably going to<br />
happen is that in 2007 &#8220;we&#8221; will be tumbling down this world<br />
ranking!    And, believe it or not, that is precisely what<br />
all my colleagues are eagerly awaiting to happen. Most of us are willing<br />
to bet our annual income on it. Belgium was among the first countries to<br />
embrace in the sixties-early seventies what was then called<br />
&#8220;modern mathematics&#8217; (you know: Venn-diagrams, sets,<br />
topology, categories (mind you, just categories not the <a
href=\"http://golem.ph.utexas.edu/category/\">n-stuff</a> ) etc.) Whole<br />
generations of promising Belgian math students were able in the late<br />
70ties, 80ties and early 90ties to do what they did mainly because of<br />
this (in spite of graduating from &#8216;just&#8217; a Belgian<br />
university, only some of which make it barely in the <a
href=\"http://www.thes.co.uk/worldrankings/\">times top 100</a> ). But<br />
then, in the &#8217;90ties politicians decided that mathematics had to<br />
be sexed-up, only the kind of mathematics that one might recognize in<br />
everyday life was allowed to be taught.     For once, I have to<br />
agree with <a href=\"http://timss.bc.edu/timss2003.html\">motl</a>.</p>
<blockquote><p> Also, the attempts to connect mathematics with<br />
the daily life are nothing else than a form of lowering of the<br />
standards. They are a method to make mathematics more attractive for<br />
those who like to talk even if they don&#8217;t know what they&#8217;re<br />
talking about. They are a method to include mathematics between the<br />
social and subjective sciences. They give a wiggle room to transform<br />
happiness, confidence, common sense, and a charming personality into<br />
good grades. </p></blockquote>
<p>Indeed, the major problem we are<br />
facing today in first year classes is that most students have no formal<br />
training at all! An example : last week I did a test after three weeks<br />
of working with groups. One of the more silly questions was to ask them<br />
for precise definitions of very basic concepts (groups, subgroups,<br />
cyclic groups, cosets, order of an element) : just 5 out of 44 were able<br />
to do this! Most of them haven&#8217;t heard of sets at all. It seems<br />
that some time ago it was decided that sets no longer had a place in<br />
secondary school, so just some of them had at least a few lessons on<br />
sets in primary school (you know the kind (probably you won&#8217;t but<br />
anyway) : put all the green large triangles in the correct place in the<br />
Venn diagram and that sort of things). Now, it seems that politicians<br />
have decided that there is no longer a place for sets in primary schools<br />
either! (And if we complain about this drastic lowering of<br />
math-standards in schools, we are thrown back at us this excellent 2003<br />
international result, so the only hope left for us is that we will fall<br />
down dramatically in the 2007 test.)    Mind you, they still give<br />
you an excellent math-education in Belgian primary and secondary schools<br />
provided you want to end up as an applied mathematician or (even worse)<br />
a statistician. But I think that we, pure mathematicians, should<br />
seriously consider recruiting students straight from Kindergarten!</p>
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		<title>Krull &#038; Paris</title>
		<link>https://lievenlebruyn.github.io/neverendingbooks/krull-paris/</link>
					<comments>https://lievenlebruyn.github.io/neverendingbooks/krull-paris/#respond</comments>
		
		<dc:creator><![CDATA[lieven]]></dc:creator>
		<pubDate>Tue, 05 Sep 2006 07:36:39 +0000</pubDate>
				<category><![CDATA[stories]]></category>
		<category><![CDATA[arty]]></category>
		<category><![CDATA[geometry]]></category>
		<category><![CDATA[Grothendieck]]></category>
		<category><![CDATA[teaching]]></category>
		<category><![CDATA[topology]]></category>
		<guid isPermaLink="false">http://www.neverendingbooks.org/?p=225</guid>

					<description><![CDATA[The Category-Cafe ran an interesting post The history of n-categories claiming that &#8220;mathematicians&#8217; histories are largely &#8216;Royal-road-to-me&#8217; accounts&#8221; To my mind a key difference is&#8230;]]></description>
										<content:encoded><![CDATA[<p>The<br />
Category-Cafe ran an interesting post <a href="http://golem.ph.utexas.edu/category/2006/09/the_history_of_ncategories.html">The history of n-categories</a><br />
claiming that &#8220;mathematicians&#8217; histories are largely<br />
&#8216;Royal-road-to-me&#8217; accounts&#8221;   </p>
<blockquote><p> To my mind a key<br />
difference is the historians&#8217; emphasis in their histories that things<br />
could have turned out very differently, while the mathematicians tend to<br />
tell a story where we learn how the present has emerged out of the past,<br />
giving the impression that things were always going to turn out not very<br />
dissimilarly to the way they have, even if in retrospect the course was<br />
quite tortuous. </p></blockquote>
<p>   Over the last weeks I&#8217;ve been writing up<br />
the notes of a course on &#8216;Elementary Algebraic Geometry&#8217; that I&#8217;ll<br />
be teaching this year in Bach3. These notes are split into three<br />
historical periods more or less corresponding to major conceptual leaps<br />
in the subject : (1890-1920) ideals in polynomial rings (1920-1950)<br />
intrinsic definitions using the coordinate ring (1950-1970) scheme<br />
theory. Whereas it is clear to take Hilbert&amp;Noether as the leading<br />
figures of the first period and Serre&amp;Grothendieck as those of the<br />
last, the situation for the middle period is less clear to me.     At<br />
first I went for the widely accepted story, as for example phrased by <a href="http://www.maths.warwick.ac.uk/~miles/">Miles Reid</a> in the<br />
Final Comments to his <a href="http://www.amazon.com/exec/obidos/tg/detail/-/0521356628?v=glance">Undergraduate Algebraic Geometry</a> course.   </p>
<blockquote><p> &#8230;<br />
rigorous foundations for algebraic geometry were laid in the 1920s and<br />
1930s by van der Waerden, Zariski and Weil (van der Waerden&#8217;s<br />
contribution is often suppressed, apparently because a number of<br />
mathematicians of the immediate post-war period, including some of the<br />
leading algebraic geometers, considered him a Nazi collaborator).
</p></blockquote>
<p>   But then I read <a href="http://www.math.jussieu.fr/~leila/grothendieckcircle/mclarty1.pdf#search=%22rising%20sea%20grothendieck%22">The Rising Sea: Grothendieck<br />
on simplicity and generality I</a> by Colin McLarty and stumbled upon<br />
the following paragraph   </p>
<blockquote><p> From Emmy Noether&#8217;s viewpoint,<br />
then, it was natural to look at prime ideals  instead of classical and<br />
generic points‚Äîor, as we would more likely say today, to  identify<br />
points with prime ideals. Her associate Wolfgang Krull did this. He gave<br />
 a lecture in Paris before the Second World War on algebraic geometry<br />
taking all  prime ideals as points, and using a Zariski topology (for<br />
which see any current  textbook on algebraic geometry). He did this over<br />
any ring, not only polynomial  rings like C[x, y]. The generality was<br />
obvious from the Noether viewpoint, since  all the properties needed for<br />
the definition are common to all rings. The expert  audience laughed at<br />
him and he abandoned the idea.  </p></blockquote>
<p>   The story seems to be<br />
due to Jurgen Neukirch&#8217;s &#8216;Erinnerungen an Wolfgang Krull&#8217;<br />
published in &#8216;Wolfgang Krull : Gesammelte Abhandlungen&#8217; (P.<br />
Ribenboim, editor) but as our library does not have this book I would<br />
welcome any additional information such as : when did Krull give this<br />
talk in Paris? what was its precise content? did he introduce the prime<br />
spectrum in it? and related to this : when and where did Zariski<br />
introduce &#8216;his&#8217; topology? Answers anyone?</p>
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