Talk:Stanislaw Ulam
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Lemberg belonged to Austria Empiry (not to Poland) in those days and Ulam was US citizen. 82.82.126.128 15:52, 10 Nov 2003 (UTC)
Ulam was a member of Lvov school of Polish mathematician, with Stefan Banach and Hugo Steinhaus. Yes, he was Jewish and he emigrated to USA. This doesn't change the fact, that he was born in Poland, learn in Poland, contributed his work in Poland. AM
I read "Dark Sun" several times. As I recall, Ulam proposed a staged thermonuclear design which used the neutron flux from the primary to compress the secondary. Teller pointed out the X-rays got to the secondary faster, which forced using them for compression, instead of neutrons. The "sparkplug" fission component added compression from the center of the secondary. --MWS 16:13, 6 October 2005 (UTC)
[edit] Ulam's Theorem
I've seen this before, and it's a neat sequence. I don't remember a proof of this conjecture, however. If there is a proof, it would be nice to see a sketch of it. If there is no proof, that would also be nice to know. (Maybe it's just really obvious, and I'm obtuse.) As far as I can tell, one wants to keep going until a power of two is reached or number known to result in a power of two is reached. How does this preclude cycles and divergent sequences?Coleca 06:49, 13 November 2005 (UTC)
I notice that the "theorem" has been deleted. I don't know if it's something that belongs in an enyclopedia, but arguing that it's just a conjecture is not sufficient justification. Coleca 08:57, 5 January 2006 (UTC)
- You're probably talking about he Collatz conjecture, also known as the Ulam conjecture. It is only a conjecture (i.e. not proven). Bubba73 (talk), 01:46, 22 December 2006 (UTC)
There is a second Ulam's conjecture which is in graph theory. It's on wikipedia as the Reconstruction conjecture--Syd Henderson 03:25, 15 June 2007 (UTC)
[edit] Name
I would request anyone who supports the present spelling to read Ulam's autobiography: Adventures of a Mathematician. His usage in English is Stanislaw and he spelled Stanislaw Mazur with an unmodified l. His friends called him Stanislaw, or Stan; his own usage seems to have been S. M. Ulam. This would be acceptable as a compromise, but it is not the most common usage. Septentrionalis PMAnderson 04:45, 27 January 2007 (UTC)
- Now changed; let anyone with a substantive case take it to WP:RM Septentrionalis PMAnderson 04:42, 29 January 2007 (UTC)
[edit] Contributions to Theoretical Biology
Ulam's contributions to mathematical models in theoretical biology should not be overlooked.
Here is a typical excerpt from a review of his work in the field.
In a paper with T. F. Smith, Myron Stein, and William Beyer, Ulam carries out an investigation of the reconstruction of evolutionary trees based on 33 species of the protein complex known as Cytochrome-C from 33 extant plants or animals. A distance metric between these similar proteins is calculated by a mathematical theory (discussed elsewhere). Hypothetical evolutionary trees are then constructed by use of linear programming methods. Agreement of the trees with generally accepted evolutionary trees was reasonably good.
These results helped evolutionary biologists resolve uncertainties regarding the placement of problematic species on the evolutionary tree. By comparing which species had the most similar forms of Cytochrome-C, evolutionary biologists were able to establish which species were most closely related on the evolutionary tree. Mathematical models such as those crafted by Ulam and his collaborators exemplified the power, utility, and importance of mathematical modeling in unifying the fields of molecular biology and macro-evolution.
