Photo de l'auteur

Stanislaw Ulam (1909–1984)

Auteur de Les aventures d'un mathématicien

10 oeuvres 246 utilisateurs 4 critiques

A propos de l'auteur

Œuvres de Stanislaw Ulam

Étiqueté

Partage des connaissances

Membres

Critiques

Indeholder "Note on the Abridged Edition", "Introduction", "1. Examples", " 1. The Infinity of Primes", " 2. Irrationality of sqrt(2)", " 3. Approximation by Rational Numbers", " 4. Transcendental Numbers: Cantor's Argument", " 5. More Proofs of Impossibility", " 5a. Sperner's Lemma", " 6. The Art and Science of Counting", " 7. Digression on the Number System and on Functions", " 8. Elementary Probability and Independence", " 9. Measure", " 10. Probability Revisited", " 11. Groups and Transformations", " 11. Homology Groups", " 12. Vectors, Matrices, and Geometry", " 13. Special Theory of Relativity as an Example of the Geometric View in Physics", " 14. Transformations, Flows, and Ergodicity", " 15. More on Iteration and Composition of Transformations", " 16. Proving the Obvious", "2. Themes, Trends, and Syntheses", "3. Relations to Other Disciplines", "4. Summary and Outlook", "Index".

Sjov bog, for en stor del af den er formet som en slags dialog mellem de to forfattere, hvor de går fra emne til emne, efterhånden som det falder dem ind. Et hundrede-sider langt kapitel med titlen "Examples" og uden en indholdsfortegnelse til underopdelingen (hvor der endda er to afsnit med nr. 11) er nok ikke den smarteste måde at tiltrække læsere på. Denne billigbogsudgave er også dårligt limet, så det er lidt på trods at man læser den.

Side 168 omtaler et spil, som Paul og Tatiana Ehrenfest foreslog i 1907. Tag to kasser og hæld nummererede kugler i, træk en tilfældig kugle og flyt den over i den anden kasse. Bliv ved med at trække kugler. Efter en tid er der ca lige mange kugler i de to kasser. Spillet er en simpel model for termodynamik og er pærelet at programmere og køre på en computer nu om dage.
… (plus d'informations)
 
Signalé
bnielsen | 1 autre critique | Nov 28, 2016 |
Review of a math fashion victim

Towards the end of his celebrated autobiography that was published in 1976, mathematician Stanislaw Ulam makes a striking remark about the way mathematics is presented:

‘(…) This was more agreeable than the present style of the research papers or books which have so much symbolism and formulae on every page. I am turned off when I see only formulas and symbols, and little text. It is too laborious for me to look at such pages not knowing what to concentrate on. I wonder how many other mathematicians really read them in detail and enjoy them.’

To wit, these are the words of someone who really has enjoyed mathematics and has been engaged in the highest ranks of the subject for almost all of his life.

For me this is quite a relevant statement, since I started studying mathematics at the University of Leiden (The Netherlands) in the year 1975. And for me it was like Ulam describes. Lectures in mathematics almost entirely involved the stating of theorems and the subsequent proofing of them. Little was said about the meaning of what was proofed, why it would be interesting, or even what the essential idea of a proof was; most of the time no background or context of any kind was given. A semester of Lebesgue integration theory was given without even referring to the problems that had arisen with more basic forms of integration like the Riemann-Stieltjes Integral. It made a lot of the matter less exiting than it could have been. And to be honest, most of the proofs stayed quite unintelligible: one could follow the details but kept missing the big picture.

The point however is, that it only now becomes clear to me that I have been a fashion victim, that what I perceived as the way mathematics was done period, was only a relatively new style of writing and teaching, a fashion that had been en vogue for only a few decades yet.

This reflection of Stanislaw Ulam is confirmed by Davis & Hersh in their 1981 book The Mathematical Experience. In a section on the philosophy of mathematics they remark:

‘The formalist style gradually penetrated downward into undergraduate mathematics teaching and, finally, in the name of “the new math”, even invaded kindergarten (…)’. (p.344)

And they continue with the observation that the formalist style might have had its longest time. Actually I’m not sure that such a thing will happen. At least some of the formalism seems to me related to a certain machismo between mathematicians; the shorter and the less intuitive the proof, the better the mathematician.

In their section on Teaching and Leaning Math, Davis & Hersh give an example of the contrast between a short formal proof and a more elaborate and a more intuitive one. It is about ‘the two-pancake problem’, the problem of cutting two pancakes in halves by cutting only once in a straight line. And the pancakes aren’t on top of each other. The example of ‘the two-pancake problem’ is put in the context of the contrast between what is called ‘the logic of scientific discovery’ and that of ‘the logic of scientific justification’. The latter being a streamlined version of the former, a logically tight presentation with all hurdles and frustrations left out. It is a linear ‘success only’ story, told in a highly stylized language, ideally that of formal logic.

Now such a linear success story has only one goal, and that is to bring home the message of success. Formal proofs do that, but with the same price paid as with other success stories: because of the lack of drama it is difficult to get engaged by them and the insights that the storyteller gained in his struggles are not the focal point of the story, only the message of success is.

So I think there’s something to say for a math education (if not math itself) where insights from storytelling are used to bring home the insights of the great mathematicians.
… (plus d'informations)
1 voter
Signalé
freetrader | 1 autre critique | Feb 27, 2009 |
Not a bad survey of what math has done in the past and where it appears to be headed (as of the mid-1960s).
I wish it had had a little more coverage of functional analysis, but OK as such books go.
 
Signalé
name99 | 1 autre critique | Nov 16, 2006 |
Ulam was born in Lwów , Poland, of an assimilated middle class Jewish family. In todays parlance he was a maths nerd, but at the same time part of the flowering of intellectual and artistic life of Cracow-Lwów in the interwar years in that part of the old Austro- Hungarian Empire.

He was influenced by Banach, Kuratowski and Mazur among others with the Scottish Café keeping a large notebook on hand so that they could write down new problems and results as they occured. This became the famous "Scottish Book".

Banach and Kuratowski knew von Neumann, and Ulam's correspondence with him led to a visit to Princeton in 1935. He stayed in the U.S. becoming a junior fellow at Harvard in 1936.
By 1943 he was at Los Alamos (again with the help of von Neumann), as a mathematician rather than a physicist or mathematical physicist but in the company of a unique group of individuals that included Bethe, Fermi, von Neumann, and Feynman.

The virtue of the book is the window that it opens on the scientific life at the creative level. His old professor and friend Steinhaus said that Ulam was the best formulator of problems in the world and it is interesting that it was him and not the physicists that devised the way to make the A Bomb work. He and his colleague Everett also showed that Teller's idea was a non starter (all done by slide rule with the MANIAC computer result later confirming it). (top) The portraits of the scientists are very good:

John von Neumann:
It was his feeling for and knowledge of the details of mathematical knowledge systems and the theoretical structure of formal systems that enabled him to conceive of flexible programming... By suitable flow diagramming and programming, an enormous variety of problems became calculable on one machine with all connections fixed. Before his invention one had to pull out wires and reconnect plug boards each time a problem was changed (? what about Flowers - see my review of "The Secret War" http://www1.dragonet.es/users/markbcki/johnson.htm ).

Enrico Fermi:
At the same time he had decided in his youth to spend at least an hour a day thinking in a speculative way. I liked this paradox of a systematic way of thinking unsystematically. Fermi had a whole arsenal of mental pictures, illustrations, as it were, of important laws and effects, and he had a great mathematical technique, which he only used when necessary. Actually it was more than mere technique; it was a method for dissecting a problem and attacking each part in turn. With our limited knowledge of introspection this cannot be explained at the present time.

The last chapter of the book is entitled Random Reflections on Mathematics and Science and it is easily worth finding the book for this chapter alone. He looks in an original way at the aesthetic character of theories, language, simulations (he invented the Monte Carlo technique), biology and much else.
… (plus d'informations)
 
Signalé
Miro | 1 autre critique | Sep 26, 2005 |

Listes

Vous aimerez peut-être aussi

Auteurs associés

Statistiques

Œuvres
10
Membres
246
Popularité
#92,613
Évaluation
4.1
Critiques
4
ISBN
21
Langues
3

Tableaux et graphiques