Ran Donagi

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Ran Donagi, is professor of mathematics in University of Pennsilvania, USA.

It happens that pure mathematicians hope that what they do will be useful for nobody — thinking in particular of military applications. This is not fully the case of R. Donagi as can be deduced from the following abstract of a talk he gave in 2005

The Standard Model encodes much of what we know about particle physics: the three forces (electromagnetism, weak and strong nuclear forces) associated with the gauge group U(1)xSU(2)xSU(3); the known particles: quarks (which make up protons and neutrons) and leptons (electrons, neutrinos), each recurring in three "generations"; and the precise rules that determine which interactions of particles and forces can occur and which are excluded. Our best hope of combining this tremendously successful quantum theory of the three forces with the remaining force, gravity (i.e. with general relativity), is based on String Theory and M-Theory.

The name of R. Donagi came first to my attention through his participation to an important book : Principles of Algebraic Geometry

P. M.

(alphacode : donagi ; numcode : 085)

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Pierre Dolbeault

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Pierre DOLBEAULT is a contemporary mathematician.

An advanced mathematical theory bears his name.

P. Dolbeault has presently a bureau in the Jussieu University of Paris.

I knew personally P. Dolbeault. But my rule, in this blog, is to write less possible about events of my life that took place between "present minus fifty years" and 2003, the date of my retirement. Hence I shall not say more here about this mathematician.

P. M.

(alphacode : dolbeault ; numcode : 010)

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Three !

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1943 : The baby is now my brother J. I am the little boy. With sister and mother.


I keep only fading images of that time in my deep memory.

P. M.

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Walt Disney

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Walt Disney, 1901 — 1966, is known in all the planet as an animation movies producer though today, children rather know his name through the Disneylands.

My first cinema in Poitiers

Up to 1950, I did not go to movies more than once a year. We had no car, hence a taxi carried everybody, father included, from home to center town. The movie theater was Le Régent (replaced today by a park for cars).

The first movies I saw were Walt Disney long cartoons. I don't remember exactly which ones I saw first. I remember faintly Pinocchio But there were certainly later Bambi, Dumbo , Cinderella — one of my first loves — and Alice in Wonderland.

Each time, the movie was of the greatest interest for me.

P. M.

(alphacode : disneywalt ; numcode : 299)

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Gustav Dirichlet

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Johann Peter Gustav Lejeune Dirichlet, 1805–1859, was a German mathematician.


Gustav Dirichlet

G. Dirichlet spent a part of his life in France and gave his name to several important theorems. His double name Lejeune Dirichlet is not the joint names of his two parents but has an other origin as explained in his biography.

One can also mistakenly think that the Lejeune Dirichlet theorems were first proved by Lejeune then generalized by Dirichlet. In fact it happens relatively frequently that a theorem bears the names of two or even three mathematicians who contributed to statement and proof. Here, the mistake may be caused by the fact that, often, in books, authors drop Lejeune and speak only of Dirichlet (as I do in the header of this page, with the first name Gustav which is sometimes his only first name in dictionaries).

A mathematical function is also given the name of Dirichlet; this function is very far from usual ones and is used only for theoretical purposes.

The above portrait is probably an early photograph.

P. M.

(alphacode : dirichlet ; numcode : 382)

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Not yet four

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1941. I am the baby. With sister and mother. War seems far from this photo but German army is in the streets of Poitiers. Often mother spoke of difficulties of that time, especially about food.



P. M.

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The man I see in mirrors

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Me, today April 19th, 2010 — 95.8 kg this morning.

P. M.

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Paul Dirac

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Paul Dirac, 1902 — 1984, was a theoretician physicist.

Paul Dirac

Paul DIRAC was famous enough to have his name in the Petit Larousse (my edition is from 1981, before his death) where he is presented as one of the creator of quantum mechanics. One can find his biography here.

For the mathematician, the name of Dirac is attached to two closely linked notions : the Dirac measure and the Dirac distribution. These notions are a good example of how ideas come from physics and can be developed by mathematicians who, spending all their time to computations and logic, don't fundamentally care about origin and use of these computations.

The one who has the A-level in sciences knows that the polynomial x²+1 has no real root and that the notion of complex number allows nevertheless to find a mathematical object x which verifies x²+1=0. The one who has the A-level in sciences knows also that a function is certainly not derivable at x if this function is not continuous at x. The Dirac distribution is the mathematical object which appears as the derivative of a function having simple discontinuities. Unfortunately, a mathematical level of at least A-level+3 is needed for a full understanding of all concepts leading to the notion of distribution.

P. M.

(alphacode : dirac ; numcode : 129)

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Céline Dion

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Céline Dion, born in 1968, is a world wide known Canadian singing girl.

By clicking on the following link

O Holy Night

One will find a list of Christmas songs among which one can hear Céline Dion singing O Holy Night which is the American version of the French Minuit Chrétiens ("Midnight Christians"), a christmas song that was well known by my parents.

P. M.

(alphacode : dionceline ; numcode : 223)

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Easter 1960

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April 17th 1960. Easter Sunday. Poitiers.

The whole seminary is present at the solemn mass in the cathedral.

In the middle of the morning, all seminarists (less than one hundred) walk from seminary to cathedral and after mass walk back to seminary. This is the custom for important catholic feasts: Christmas, Easter, All Saint's Day. And I do it since 1958 All Saint's Day (November 1st).

The walk path from seminary to cathedral is marked with yellow on the photo. Note that a few buildings of this part of the town were replaced by new ones since 1960.


P. M.

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Ulisse Dini

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Ulisse DINI, 1845 — 1918, was an italian mathematician.


Ulisse DINI

One can read here his biography.

Basic mathematicians know him today as the author of a classical theorem of functional analysis.

Note that the theorem needs the continuity of the simple limit. One has a counterexample by taking f_n(x)=x^1/n on the interval [0,1].

P. M.


(alphacode : dini ; numcode : 376)

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Jean Dieudonné

Jean Dieudonné, 1906-1992, was a French mathematician.

photography found in the website matematica.uni-bocconi.it

Basic mathematicians know probably him as the author of Foundations of Modern Analysis, a book he wrote first in english then published in French. This book was a "must" during the sixties for any person interested in mathematical analysis. Initially, the author certainly did not view the book as the first of a series but he wrote high level continuations which constituted finally a 9 volumes treatise.

For high level mathematicians, Jean Dieudonné appears rather mainly as a researcher, co-founder and, during all his life, active member of the Bourbaki group.

Detailed biographies at www-groups.dcs.st-and.ac.uk and Wikipedia

P. M.

(alphacode : dieudonne ; numcode 131)

The same four

In the same place.

P. M.

Marc Diener

Marc Diener is a contemporary French mathematician.

He is joint author of the book (in French) on Nonstandard Analysis I mentioned a few days ago.

More recently, he published - still as joint author but not with the same person - a book on the same subject. This book is now in English.

P. M.

(alphacode : dienermarc ; numcode : 397)

Neil Diamond

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Neil Diamond, born in 1941 (like me), is a US song writer and singer.

P. M.

(alphacode : diamondneil ; numcode : 251)

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Alfred De Vigny

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Alfred Comte De Vigny, 1797 - 1863, was a French writer.

His poems are studied by teenagers in colleges of France and this is the way I knew firstly this author.

One day, I bought by random choice a small pocket book containing some of his writings (ISBN 2-87714-344-9). Here are a few notes following my reading and my interest to this author:

1. Surprised to learn that Alfred de Vigny had a military career.


2. When buying, I thought it was poetry but it is only a story; in fact three stories packed in one.


3. Interesting social description of people during French revolution (3rd story). Infos of A. de V. were certainly fresher than today.
   


4. Pages of main interest to my eyes are in the dialog p. 18-19; more precisely in the replies of Dr Noir "Dieu du ciel ...", "Il vous y enfoncera ...", "Méprisez mais n'étouffez pas ...".
   
   
5. The author is one of the few first persons that are not only known by painting but also by photograph.
   
   
6. A curious fact, also is that the famous words "comediante tragediante" - from Pope speaking of Napoleon 1st - have no other source than A. de Vigny writings.
   

P. M.

(alphacode : devignyalfred ; numcode : 348)

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My sister, my brothers and me

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R. Descombes

yes-no's

René Descartes

René Descartes, 1596 - 1650, was a French thinker.

R. Descartes is known in all places in the world where one deals with philosophy. Moreover anyone who draws a diagram with two axes of coordinates uses R. Descartes' name when speaking of cartesian coordinates.

R. Descartes was born in Indre-et-Loire (department in center of France) and studied in the university of Poitiers (my beloved birthplace); but he spent almost all the remainder of his life in the Dutch Republic (wikipedia).

P.M.

(alphacode : descartes ; numcode : 431)

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kindergarten

France, Poitiers, rue Condorcet.

This is a recent photo of the buildings where I had my kindergarten more than 60 years ago. The buildings have exactly their aspect of 1950. The blue X marks the door which led to the classrooms of the kindergarten. The building with a red X was a free health center of the Red Cross and could communicate with the kindergarten.



On beginning of mornings, the grid was closed. And, with the other boys and girls, I used to wait for the two nuns who managed the kindergarten.

P.M.

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What did you say ?

You said "Collix is mad".

I say that you didn't say that Collix is mad.

You said "I am a person who is liable to say that somebody is mad".

P.M.

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Georges De Rham

Georges De Rham, 1903 - 1990, was a Swiss mathematician.

An advanced notion in abstract geometry bears his name : The De Rham Cohomology.

P. M.

(alphacode : derham ; numcode : 015)

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John Denver

John Denver, 1943 - 1997, was a US songwriter and singer.

In this Soundamerica page, one can hear him singing the well known Little Drummer Boy song.

P. M.


(alphacode : denverjohn ; numcode : 236)

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Jean Delsarte

Jean Delsarte, 1903 - 1968, was a French mathematician.

He was a founder member of the Bourbaki group.

Jean Delsarte

P. M.

(alphacode : bourbakithree ; numcode : 126)

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the day before

Thinking of the day.

Philosophy is much much more difficult than science

however

any human being who is able to remember what he/she did the day before

is able to understand philosophy

P. M.

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