Tag: Grothendieck

On categories, go and the book $\in$

Published July 24, 2014 by lievenlb

A nice interview with Jacques Roubaud (the guy responsible for Bourbaki’s death announcement) in the courtyard of the ENS. He talks about go, categories, the composition of his book $\in$ and, of course, Grothendieck and Bourbaki.

Clearly there are pop-math books like dedicated to $\pi$ or $e$, but I don’t know just one novel having as its title a single mathematical symbol : $\in$ by Jacques Roubaud, which appeared in 1967.

The book consists of 361 small texts, 180 for the white stones and 181 for the black stones in a game of go, between Masami Shinohara (8th dan) and Mitsuo Takei (2nd Kyu). Here’s the game:

In the interview, Roubaud tells that go became quite popular in the mid sixties among French mathematicians, or at least those in the circle of Chevalley, who discovered the game in Japan and became a go-envangelist on his return to Paris.

In the preface to $\in$, the reader is invited to read it in a variety of possible ways. Either by paying attention to certain groupings of stones on the board, the corresponding texts sharing a common theme. Or, by reading them in order of how the go-game evolved (the numbering of white and black stones is not the same as the texts appearing in the book, fortunately there’s a conversion table on pages 153-155).

Or you can read them by paragraph, and each paragraph has as its title a mathematical symbol. We have $\in$, $\supset$, $\Box$, Hilbert’s $\tau$ and an imagined symbol ‘Symbole de la réflexion’, which are two mirrored and overlapping $\in$’s. For more information, thereader should consult the “Dictionnaire de la langue mathématique” by Lachatre and … Grothendieck.

According to the ‘bibliographie’ below it is number 17 in the ‘Publications of the L.I.T’.

Other ‘odd’ books in the list are: Bourbaki’s book on set theory, the thesis of Jean Benabou (who is responsible for Roubaud’s conversion from solving the exercises in Bourbaki to doing work in category theory. Roubaud also claims in the interview that category theory inspired him in the composition of the book $\in$) and there’s also Guillaume d’Ockham’s ‘Summa logicae’…

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Oulipo’s use of the Tohoku paper

Published July 17, 2014 by lievenlb

Many identify the ‘Tohoku Mathematical Journal’ with just one paper published in it, affectionately called the Tohoku paper: “Sur quelques points d’algèbre homologique” by Alexander Grothendieck.

In this paper, Grothendieck reshaped homological algebra for Abelian categories, extending the setting of Cartan-Eilenberg (their book and the paper both appeared in 1957). While working on the Tohoku paper in Kansas, Grothendieck did not have access to the manuscript of the 1956 book of Cartan-Eilenberg, about which he heard from his correspondence with Serre.

Concerning the title, an interesting suggestion was made by Mathieu Bélanger in his thesis “Grothendieck et les topos: rupture et continuité dans les modes d’analyse du concept d’espace topologique”, (footnote 18 on page 164):

“There is a striking resemblance between the title of the Grothendieck’s article “Sur quelques points d’algèbre homologique”, and that of Fréchet‘s thesis “Sur quelques points d’analyse fonctionelle”. Why? Grothendieck remains silent about it. Perhaps he saw a methodological similarity between the introduction, by Fréchet, of abstract spaces in order to develop the foundations of functional calculus and that of the Abelian categories he needed to clarify the homological theory. Compared with categories of sets, groups, topological spaces, etc. that were used until then, Abelian categories are in effect abstract categories.”

But, what does this have to do with the literary group OuLiPo (ouvroir de littérature potentielle, ‘workshop of potential literature’)?

Oulipo was founded in 1960 by Raymond Queneau and François Le Lionnais. Other notable members have included novelists Georges Perec and Italo Calvino, poets Oskar Pastior, Jean Lescure and poet/mathematician Jacques Roubaud.

Several members of Oulipo were either active mathematicians or at least had an interest in mathematics. Sometimes, Oulipo is said to be the literary answer to Bourbaki. The group explored new ways to create literature, often with methods coming from mathematics or programming.

One such method is described in “Chimères” by Le Lionnais:

One takes a source text A. One ’empties’ it, that is, one deletes all nouns, adjectives and verbs, but marks where they were in the text. In this way we have ‘prepared’ the text.

Next we take three target texts and make lists of words from them, K the list of nouns of the first, L the list of adjectives of the second and M the list of verbs of the third. Finally, we fill the empty spaces in the source text by words from the target lists, in the order that they appeared in the target texts.

In the example Le Lionnais gives, the liste M is the list of all verbs appearing in the Tohoku paper.

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Grothendieck’s Café

Published July 1, 2014 by lievenlb

“A story says that in a Paris café around 1955 Grothendieck asked his friends “what is a scheme?”. At the time only an undefined idea of “schéma” was current in Paris, meaning more or less whatever would improve on Weil’s foundations.” (McLarty in The Rising Sea)

Finding that particular café in Paris, presumably in the 5th arrondissement, seemed like looking for a needle in a haystack.

Until now.

In trying to solve the next riddle in Bourbaki’s death announcement:

A reception will be held at the Bar ‘The Direct Products’, at the crossroads of the Projective Resolutions (formerly Koszul square)

I’ve been reading Mathematics, a novel by Jacques Roubaud (the guy responsible for the announcement) on Parisian math-life in the 50ties and 60ties.

It turns out that the poor Bourbakistas had very little choice if they wanted to have a beer (or coffee) after attending a seminar at the IHP.

On page 114, Roubaud writes:

“Père Plantin presided over his bar, which presided over the Lhomond/Ulm street corner. It is an obvious choice. rue Pierre-et-Marie-Curie had no bars; rue d’Ulm had no bars in eyeshot either. If we emerged, as we did, on this side of the Institut Henri Poincaré (for doing so on the other side would have meant fraternizing with the Spanish and Geography students in the cafés on rue Saint-Jacques, which was out of the question), we had no choice. Café Plantin had a hegemony.”

It is unclear to me whether Plantin was once actually the name of the café, or that it’s just Roubaud’s code-word for it. At other places in the book, e.g. on pages 82 and 113, he consistently writes “Plantin”, between quotes.

Today, the café on the crossroads of rue d’Ulm (where the Ecole Normal Superieure is located) and de rue Lhomond is the Interlude Café

and here’s what Roubaud has to say about it, or rather about the situation in 1997, when the French version of his book was published:

“the thing that would currently be found at the very same corner of rues Lhomond/Ulm would not be what I am here terming “Plantin”.”

So, we can only hope that the Café ‘Aux Produits Directs’ was a lot cosier, way back then.

But let us return to Grothendieck’s “What is a scheme?” story.

Now that we have a fair idea of location, what about a possible date? Here’s a suggestion: this happened on monday december 12th, 1955, and, one of the friends present must have been Cartier.

Here’s why.

The very first time the word “schéma” was uttered, in Paris, at an official seminar talk, was during the Cartan seminar of 1955/56 on algebraic geometry.

The lecturer was Claude Chevalley, and the date was december 12th 1955.

I’m fairly certain Grothendieck and Cartier attended and that Cartier was either briefed before or understood the stuff at once (btw. he gave another talk on schemes, a year later at the Chevalley seminar).

A couple of days later, on december 15th, Grothendieck sends a letter to his pal Serre (who must have been out of Paris for otherwise they’d phone each other) ending with:

Note the phrase: I am exploiting him most profitably. Yes, by asking him daft questions over a pint at Café “Plantin”…

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the birthday of Grothendieck topologies

Published June 23, 2014 by lievenlb

This is the story of the day the notion of ‘neighbourhood’ changed forever (at least in the geometric sense).

For ages a neighbourhood of a point was understood to be an open set of the topology containing that point. But on that day, it was demonstrated that the topology of choice of algebraic geometry, the Zariski topology, needed a drastic upgrade.

This ultimately led to the totally new notion of Grothendieck topologies, which aren’t topological spaces at all.

Formally, the definition of Grothendieck topologies was cooked up in the fall of 1961 when Grothendieck visited Zariski, Mike Artin and David Mumford in Harvard.

The following spring, Mike Artin ran a seminar resulting in his lecture notes on, yes, Grothendieck topologies.

But, paradigm shifts like this need a spark, ‘une bougie d’allumage’, and that moment of insight happened quite a few years earlier.

It was a sunny spring monday afternoon at the Ecole Normal Superieure. Jean-Pierre Serre was giving the first lecture in the 1958 Seminaire Claude Chevalley which that year had Chow rings as its topic.

That day, april 21st 1958, Serre was lecturing on algebraic fibre bundles:

He had run into a problem.

If a Lie group $G$ acts freely on a manifold $M$, then the set of $G$-orbits $M/G$ is again a manifold and the quotient map $\pi : M \rightarrow M/G$ is a principal $G$-fibre bundle meaning that for sufficiently small open sets $U$ of $M/G$ we have diffeomorphisms

$\pi^{-1}(U) \simeq U \times G$

that is, locally (but not globally) $M$ is just a product manifold of $G$ with another manifold and the $G$-orbits are all of the form $\{ u \} \times G$.

The corresponding situation in algebraic geometry would be this: a nice, say reductive, algebraic group $G$ acting freely on a nice, say smooth, algebraic variety $X$. In this case one can form again an orbit space $X/G$ which is again a (smooth) algebraic variety but the natural quotient map $\pi : X \rightarrow X/G$ rarely has this local product property…

The reason being that the Zariski topology on $X/G$ is way too coarse, it doesn’t have enough open sets to enforce this local product property.

(For algebraists: let $A$ be an Azumaya algebra of rank $n^2$ over $\mathbb{C}[X]$, then the representation variety $\mathbf{rep}_n(A)$ is a principal $\mathbf{PGL}_n$-bundle over $X$ but is only local trivial in the Zariski topology when $A$ is a trivial Azumaya algebra, that is, $End_{\mathbb{C}[X]}(P)$ for a rank $n$ projective module $P$ over $\mathbb{C}[X]$.)

But, Serre had come up with a solution.

He was going to study fibre bundles which were locally ‘isotrivial’, meaning that they had the required local product property but only after extending them over an unamified cover $Y \rightarrow X$ (what we now call, an etale cover) and he was able to clasify such fibre bundles by a laborious way (which we now call the first etale cohomology group).

The story goes that Grothendieck, sitting in the public, immediately saw that these etale extensions were the correct generalization of the usual (Zariski) localizations and that he could develop a cohomology theory out of them in all dimensions.

According to Colin McLarty Serre was ‘absolutely unconvinced’, since he felt he had ‘brutally forced’ the bundles to yield the $H^1$’s.

We will never known what Serre actually wrote on the blackboard on april 21st 1958.

The above scanned image tells it is an expanded version of the original talk, written up several months later after the ICM-talk by Grothendieck in Edinburgh.

By that time, Grothendieck had shown Serre that his method indeed gives cohomology in all dimensions,and convinced him that this etale cohomology was likely to be the “true cohomology needed to prove the Weil conjectures”.

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le petit village de l’Ariège

Published March 28, 2013 by lievenlb

For me this quest is over. All i did was following breadcrumbs left by others.

Fellow-travelers arrived there before. What did they do next?

The people from the esoteric site L’Astrée, write literary texts on Grothendieck, mixing strange details (such as the kiosque de la place Pinel, the village of Fougax-et-Barrineuf and even ‘Winnie’ or ‘Fred le Belge, notre indic vers Grothendieck’) with genuine finds, such as this ‘petite annonce’ in the journal for this le 09

which reads:

“RETRAITE (PROFESSEUR UNIVERSITE) CHERCHE -eau de vie de pays pour mes préparations de plantes. Ecrire à M. Grothendieck.”

Caterine Aira makes a movie

Most of you will be perfectly happy to know Grothendieck lives in a tiny village close to the market-town of Saint-Girons. A few may click through the map below to satisfy their need to know the name of ‘le petit village de l’Ariège’.

To do what exactly, i wonder.

You can write a letter, but it will be returned unopened.

You can email ‘la Mairie’ (btw. it’s the ‘orange’-address rather than the ‘wanadoo’ ones), but i doubt they’ll update their Wikipedia-page to acknowledge Grothendieck among the ‘Personnalités liées à la commune’.

You can go there in person to hear the villagers out, but, until you’re a ‘résident permanent’, you will be considered an outsider, and treated as one.

If it’s knowledge you’re after, Grothendieck made it plain he no longer wants to be part of the mathematical society.

His mathematical brain is scattered in the 20.000 pages, kept in 5 boxes at the university of Montpellier. This is the genuine treasure, and should be made public without further delay.

I trust you’ll proceed wisely.

To ‘Monsieur Alexandre’, on his 85th birthday:
happier days!

Previous in this series:
– Vendargues
– Mormoiron
– Massy
– Olmet-et-Villecun
– un petit village de l’Ariège
– Saint-Girons
‘

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G-spots : Saint-Girons

Published March 25, 2013 by lievenlb

Roy Lisker (remember him from the Mormoiron post?) has written up his Grothendieck-quest(s), available for just 23$, and with this strange blurb-text:

“The author organized a committee to search for him that led to his discovery, in good health and busily at work, in September, 1996. This committee has since become the Grothendieck Biography Project. All of this is recorded in a 300 page account in 3 parts.”

Probably he refers to the trip made by Leila Schneps and Pierre Lochak, nicely described in Sam Leith’s The Einstein of maths:

“One of the last members of the mathematical establishment to come into contact with him was Leila Schneps. Through a series of coincidences, she and her future husband, Pierre Lochak, learned from a market trader in the town he left in 1991 that ‘the crazy mathematician’ had turned up in another town in the Pyrenees. Schneps and Lochak in due course staked out the marketplace of the town, carrying an out-of-date photograph of Grothendieck, and waited for the greatest mathematician of the 20th century to show up in search of beansprouts.

‘We spent all morning there in the market. And then there he was.’ Were they not worried he’d run away? ‘We were scared. We didn’t know what would happen. But he was really, really nice. He said he didn’t want to be found, but he was friendly. We told him that one of his conjectures had been proved. He had no idea. He’d stopped being interested in maths at that stage. He thought his unpublished work would all have been long forgotten.’”

To city-cats this may seem an improbable coincidence, but if you live in the French mountains for some time, you learn to group your shoppings, and do them on market-days. The nearest market-town, where you can find a decent ‘boulangerie’ or supermarket, may be just 20 kms down the road, but it’ll take you close to an hour to get there.

If you sit near the town-fountain on market-days, for some weeks, you will have seen most of the people living in the vast neighborhood.

So, we’d better try to find Leila’s market-town.

One of the nicer talks on the life of Grothendieck was given by Winfried Scharlau (who also has two books on offer on Grothendieck’s life, seems to become an emerging bisiness …) at the IHES Grothendieck colloque.

Colloque Grothendieck Winfried Scharlau par Ihes_science

This video is stuffed with unknown (at least to me) pictures of Grothendieck, his places at Mormoiron and Villecun and of his four children still living in France. Highly recommended!

But, the lecture has a very, very strange ending.

At 1hr 06.51 into the video he shows the slide reproduced on the left below and says: “Okay and here’s a picture on which I will not further comment. That’s the last thing I want to show you. I thank you very much for your patience.”

Leila Schneps has a page with pictures on her website, including 3 pictures of her house, and then the one on the right above, merely described as ‘Another house’.

And then there’s this paragraph from Roy Lisker’s (him again) Travelogue-France (March 8-April 5, 2005) part 2

“I left the IHP around 11 to return to the CNRS research center at 175 rue du Chevaleret. Pierre Lochak and I discussed the possibility of my going to the town of St. Giron outside of Toulouse to make another impromptu visit to La Maison d’Alexandre Grothendieck.”

So, here we have three founding members of the Grothendieck circle linking publicly to the same picture of that one place they want to keep secret at all cost?

Dream on!

If you followed this series at all and have looked at the pictures of Grothendieck’s houses in Mormoiron or Villecun it is hard to imagine him living in a bourgeois-house, dating from the end of the 19th century, in a medium-sized market-town.

Still, it is quite likely that the picture is indeed taken in Saint-Girons, on some saturday in 1996 when Leila and Pierre bumped into Grothendieck on the market in Saint-Girons.

After all, Saint-Girons is the market-town closest to the final Grothendieck-spot…

Added after Grothendieck’s death on november 13th 2014: Here I got things wrong. For example, from the article La vie secrète d’un génie des maths à Lasserre it is clear that ‘another house’ is indeed Grothendieck’s last house, and it is not situated in Saint-Girons, but in the nearby village Lasserre.

Previous in this series:
– Vendargues
– Mormoiron
– Massy
– Olmet-et-Villecun
– un petit village de l’Ariège

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G-spots : un petit village de l’Ariège

Published March 24, 2013 by lievenlb

We would love to conclude this series by finding the location of the “final” Grothendieck-spot, before his 85th birthday, this thursday.

But, the road ahead will be treacherous, with imaginary villages along the way and some other traps planted by the nice people of the Grothendieck Fan Club

It is well-known that some members (if not all) of the GFC know the exact location of Grothendieck’s hideout in the Pyrenees. Trying to pry this information from them, pledging to keep the name secret, is described as ‘solving an equation in n unknowns’ in the article Le trésor oublié du génie des maths (h/t +David Roberts):

“Cela fait aujourd’hui vingt-deux ans qu’il vit reclus au pied des Pyrénées, dans un village où personne ne va par hasard et dont le nom doit rester secret. Il le souhaite et ceux qui, de loin, le protègent le souhaitent également. Obtenir l’adresse contre l’assurance de ne pas le déranger prend le temps de résoudre une équation à «n» inconnues. Se poster devant chez lui permet de constater qu’il est bien vivant au milieu d’un village qui le regarde comme «le savant» sans chercher à en savoir plus. A 84 ans, il vient se chauffer au soleil devant son portail puis rentre dans sa maison où nul ne pénètre.”

As we don’t want to take this vow of secrecy, we will have to rely on the few hints they left in the literature. Presumably, the most trustworthy information is to be found in Pierre Cartier’s paper A country of which nothing is known but the name, Grothendieck and “motives”:

“As I already said, he retired in 1988, and has lived since then in self-imposed exile. At ﬁrst he lived near the Fontaine de Vaucluse, in the middle of a little vineyard that he cultivated, and near to his daughter Johanna and his grandchildren. But later he broke oﬀ every family relation. He didn’t seem to mind that the place where he lived was located so near to the infamous Camp du Vernet which played a sad role in his childhood. He lived for years without any contact with the outside world and only a few people even knew where he was. He chose to live alone, considered by his neighbors as a “retired mathematics professor who’s a bit mad”.”

There is a small (but for our purposes important) addition to the first sentence in the French version:

“… il a pris sa retraite en 1988, et vit depuis un exil intérieur dans un petit village de l’Ariège.”

This addition makes our quest a bit more ‘doable’. The department of l’Ariège is one of the lesser populated ones in France (having less that 150.000 inhabitants), and has ‘only’ 332 villages.

One can divide this number roughly by 2, leaving out the larger villages and towns and those situated in the higher mountains, where living must be extremely difficult for an 85 year old.

An alternative reason for leaving out the more southern villages is Cartier’s claim that ‘le petit village’ is close to the Camp du Vernet, which is the place from which Grothendieck’s father was deported to Auschwitz.

This former concentration camp is located in Le Vernet, close to the town of Pamiers (central upper part of the map).

So, one can safely assume that the final G-spot must lie on the map below (click on it to navigate and explore).

Previous in this series:
– Vendargues
– Mormoiron
– Massy
– Olmet-et-Villecun

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G-spots : Olmet-et-Villecun

Published March 23, 2013 by lievenlb

Before we start the quest for the final G-spot, hopefully in time for Grothendieck’s 85th birthday, one more post on Alexandre’s ‘hippy-days’.

In the second part of Allyn Jackson’s “The Life of Alexandre Grothendieck” she tells the story that AG, while touring the US to spread the gospel of the eco-mouvement “Survivre et Vivre” (the deal was that he gave 1 math-talk if he was allowed to give another one on ecology/politics), met a graduate student of Daniel Gorenstein, Justine Skalba, who quickly became a G-groupie and returned with him after the US-trip to France, where she lived with him for two years (and had one child with him, John, who later also became a mathematician).

Allyn Jackson writes:

“In early 1973 he (AG) and Skalba moved to Olmet-le-sec (probably she means: Olmet sec, so without any additions), a rural village in the south of France. This area was at the time a magnet for hippies and others in the counterculture movement who wanted to return to a simpler lifestyle close at hand (I would have added: and, it still is). Here Grothendieck again attempted (he did this once before in his Parisian period, setting up a commune in Chatenay-Malabry) to start up a commune, but personality conflicts led to its collapse. At various times three of Grothendieck’s children came to live in the Paris commune and in the one in Olmet (probably this being: Johanna, Mathieu and Alexandre who even today maintain an alternative lifestyle). After the commune disolved, he moved with Skalba and his children to Villecum, a short distance away.”

As Yves Ladegaillerie tells Jackson, Grothendieck lived an ascetic, unconventional life in an old house without electricity in Villecun, about thirty-five miles outside of Montpellier. Ladegaillerie remembered seeing Justine Skalba and her baby there. Many friends, acquantances and students went to visit Grothendieck there, including people from the ecology movement.

Here’s the (in)famous house in Villecun (h/t Winfried Scharlau)

And, if you are a bit like me, wanting to see everything with G-earth or maps, here’s the scenery (click on the image to be there).

Again, if someone at the Mairie d’Olmet-et-Villecun reads this, please consider adding to your list of ‘Personnalités liées à la commune’

– Michel Chevalier
– Paul Dardé

this one:

– Alexandre Grothendieck

Merci infiniment!

Previous in this series:

– Vendargues
– Mormoiron
– Massy

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G-spots : Massy

Published March 21, 2013 by lievenlb

One week from now, Alexandre Grothendieck will turn 85. Today, we’ll have a glance at his ‘wilder years’, the early 70ties, when he resigned from the IHES and became one of the leading figures in the French eco-movement. This iconic picture is from those days

The text reads:

“Schurik entre les “frères ennemis” Gaston Galan et Dyama, rue Polonceau.
Derrière, Chantal et Motito (femme et fille de Gaston).”

Schurik (that is, AG) between the ‘hostile brothers’ Gaston Galan and Dyama in the ‘rue Polonceau’. Behind, Chantal and Motito (wife and daughter of Gaston).

However, if you stroll down the Rue Polonceau via StreetView (note to self: high time to revisit Paris IRL) it is unclear where this picture might have been taken. One notable exception perhaps, at 38, Rue Polonceau.

Today, this address houses the feminist group Ruptures with the noble goal to establish a society based on a genuine equality between women and men.

“L’association se donne pour objectif de substituer à la société patriarcale une société fondée sur une égalité réelle et pas seulement formelle entre les femmes et les hommes dans le domaine économique, social, politique et culturel. Elle est basée sur la laïcité et la parité.”

Besides, they want to encourage cooperation with other movements striving for a better world:

“Convergences des luttes féministes, altermondialistes, écologistes, antiracistes”

It is thus very well possible that this address was already used in the 70ties by similar social groups, such as the ecological movement “Survivre et Vivre” (Survive and Live), a movement founded in 1970 by three renowned mathematicians: Grothendieck, Claude Chevalley and Pierre Samuel. The origins and evolution of Survivre et Vivre are nicely described on this page at Science et Société.

So, whoever wrote that text beneath the photograph is probably right, though I’d love to hear more details. Still, this picture was the first thing on my mind when i found the place where Grothendieck lived in his IHES-years (and shortly afterwards).

The first issue of the Bulletin of Survivre et Vivre (btw. most issues are available from the Grothendieck circle and are fun reading material if you are, like me, in constant need to brush up your French) concludes with a list of the names, professions and addresses of the group’s members (25 at the time, including AG’s mother-in-law (Julienne Dufour, mother of his wife Mireille Dufour) and his son (from another mother) Serge):

So, here we are, Grothendieck lived with his wife, children (apart from Serge who was at the time based in Nice) and mother-in-law at 2, Avenue de Verrières, Massy, France

If you click on the picture, you can walk around this G-spot. Thanks to Igor Babou (see comments), for correcting me on this G-spot. From Igor’s comment:

“Actually, the AG ex house is not exactly located on the street: its door is at the opposite of the Verriere avenue, in front of the Massy Station. The house seems to be unoccupied, and has no name on its mailbox. All the blinds were closed. I just saw a bill saying “security camera”… not very “Grothendieck spirit”…

Here you will see the green portal of the house, surrounded by the big trees and between the two cars. Unfortunalety, the house is hard to see from the street, and google hasn’t done any picture of it.”

If some of you have better info on this or other Grothendieck-spots, please fill me in.
I’m bound to travel south, possibly in search for more information, end of next week…

Previous in this series:
– Vendargues
– Mormoiron

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G-spots : Mormoiron

Published March 18, 2013 by lievenlb

With Grothendieck’s 85th brithday coming up, march 28th, we continue our rather erratic quest to locate the spots that once meant a lot to him.

Ever wondered what Grothendieck’s last-known hideout looked like? Well, here’s the answer:
(h/t gruppe eM)

And, here’s the story.

One of the stranger stories to be found on the web is the Grothendieck quest by Roy Lisker. In 1988, after AG declined the Crafoord Prize, Roy convinced an editor of Le Nouvel Observateur to hire him to uncover the whereabouts of Alexandre Grothendieck and, if possible, to interview him.

The ‘quest’ is an hilarious account of Roy’s attempts to prise AG’s address out of the people from the Montpellier maths department, his subsequent travels and stay at Grothendieck’s place.

He put the text online in 2008 and made it intentionally opaque wrt. AG’s phone number and address:

“His phone, if in fact this notorious hermit bothered with such contrivances, was unlisted.”

“…of his adopted village of Lessmoiron (after a 20 year silence it is permissible to reveal its name) , in the department of the Vacluse, a region of France long habituated to the herbergement of exiled or alienated Popes.”

By that time the Grothendieck-Serre correspondence had been published for over 4 years, including a letter dated 2 september 1984, giving away this ‘secret information’:

So, not only do we have a phone number (today it would be 0033(0)4 90 61 88 30), but also that AG lived in the hamlet “Les Aumettes” in the village of Mormoiron (and not ‘Less’moiron, duh), close to the famous (to any bicyclist) Mont Ventoux.

From Roy’s quest we learn that it is about 3 kms from the center of Mormoiron and that
“Grothendieck’s cottage was built up against a hillside, it’s conical shape hugging the hill like the helmet of a medieval knight. The lower entrance was graced by a pair of sturdy French windows. Above these, at the level of the attic, two tiny rectangular windows filtered light into the bedroom.”

If you want to explore the immediate neighborhood of Les Aumettes, click on the picture below (bonus points for anyone who is able to pinpoint the exact location on the map).

If someone at the Mairie de Mormoiron reads this, please consider adding to your list of ‘Personnalités liées à la commune’

– Raymond Guilhem de Budos (? – 1363), neveu de Clément V, seigneur de Clermont, Lodève, Budos,Beaumes-de-Venise, Bédoin, Caromb, Entraigues, Loriol et Mormoiron, gouverneur de Bénévent, Maréchal de la Cour pontificale et Recteur du Comtat Venaissin de 1310 à 1317.
– Guillaume-Emmanuel-Joseph, baron Guilhem de Sainte-Croix, (1746-1809), membre de l’Institut, auteur d’un essai Examen critique des anciens historiens d’Alexandrie, couronné par l’Académie des Inscriptions et Belles-Lettres en 177224.
– Paul Vialis, ancien maire de Moirmoiron ou il est né en 1848, et député de Vaucluse.
– Albert Schou (da), (27 mars 1849 – 4 février 1900), photographe danois

this one:

– Alexandre Grothendieck (né en 1928), mathématicien français ayant reçu la Médaille Fields.

Merci!

Previous in this series:
– Vendargues

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